Maximizing the retention of antigen specific lymphocyte function after cryopreservation

High-dimensional Immune Profiles and Machine Learning May Predict Acute Myeloid Leukemia Relapse Early following Transplant

Identification of early immune signatures associated with acute myeloid leukemia (AML) relapse following hematopoietic stem cell transplant (HSCT) is critical for patient outcomes. We analyzed PBMCs from 58 patients with AML undergoing HSCT, focusing on T cell subsets and functional profiles. High-dimensional flow cytometry coupled with Uniform Manifold Approximation and Projection dimensionality reduction and PhenoGraph clustering revealed distinct changes in CD4+ and CD8+ T cell populations in 16 patients who relapsed within 1 y of HSCT. We observed increased IL-2, IL-10, and IL-17-producing CD4+ T cells, alongside decreased CD8+ T cell function early in relapsing patients. Notably, relapsing patients exhibited increased TCF-1intermediate cells, which lacked granzyme B or IFN-γ production in the CD4+ T cell compartment. We then developed a supervised machine learning algorithm that predicted AML relapse with 90% accuracy within 30 d after HSCT using high-throughput assays. The algorithm leverages condensed immune phenotypic data, alongside the ADASYN algorithm, for data balancing and 100 rounds of XGBoost supervised learning. This approach holds potential for detecting relapse-associated immune signatures months before clinical manifestation. Our findings demonstrate a distinct immunological signature potentially capable of predicting AML relapse as early as 30 d after HSCT.

Improving Reliability of Immunological Assays by Defining Minimal Criteria for Cell Fitness

Human PBMC-based assays are often used as biomarkers for the diagnosis and prognosis of disease, as well as for the prediction and tracking of response to biological therapeutics. However, the development and use of PBMC-based biomarker assays is often limited by poor reproducibility. Complex immunological assays can be further complicated by variation in cell handling before analysis, especially when using cryopreserved cells. Variation in postthaw viability is further increased if PBMC isolation and cryopreservation are done more than a few hours after collection. There is currently a lack of evidence-based standards for the minimal PBMC viability or "fitness" required to ensure the integrity and reproducibility of immune cell-based assays. In this study, we use an "induced fail" approach to examine the effect of thawed human PBMC fitness on four flow cytometry-based assays. We found that cell permeability-based viability stains at the time of thawing did not accurately quantify cell fitness, whereas a combined measurement of metabolic activity and early apoptosis markers did. Investigation of the impact of different types and levels of damage on PBMC-based assays revealed that only when cells were >60-70% live and apoptosis negative did biomarker values cease to be determined by cell fitness rather than the inherent biology of the cells. These data show that, to reproducibly measure immunological biomarkers using cryopreserved PBMCs, minimal acceptable standards for cell fitness should be incorporated into the assay protocol.

Define Critical Parameters of Trastuzumab-Mediated ADCC Assays via Assay Optimization Processes, Focusing on the Impact of Cryopreserved Effector Cells on Assay Performance

The mechanisms of mAb-induced ADCC have been well established. However, the ADCC bioassays used to quantify mAb-induced ADCC require continued development/refinement to properly assess and compare the potency of newly developed therapeutic mAbs and biosimilars to meet regulatory requirements. We used trastuzumab and a lactate dehydrogenase (LDH)-based ADCC bioassay as a model to define critical parameters of the ADCC bioassay, describing how several bioassay parameters, including preparation of effector cells, E/T ratio, target cell selection, bioassay media components, and treatment time can influence the data quality of the ADCC activity. We confirm that a 4 to 24 h recovery cultivation is required to restore peripheral blood mononuclear cells (PBMCs) and natural killer (NK) cell activity toward ADCC when using cryopreserved PBMCs. Furthermore, we delineated the cellular mechanisms underlying the restored ADCC activity following the recovery cultivation. We observed that CD69, an early marker of NK cell activation, was upregulated and a new subset CD56dim/CD16dim population was dramatically increased in the recovered NK cells, which led to an increase in expression and secretion of perforin, granzyme B, and cytokine production. This study provides comprehensive technical insights into ADCC bioassay optimization to inform trastuzumab biosimilar development. The knowledge gained from this study can also be leveraged to guide bioassay development for therapeutic mAbs with ADCC as the primary mechanism of action.

Technical pitfalls when collecting, cryopreserving, thawing, and stimulating human T-cells

The collection, cryopreservation, thawing, and culture of peripheral blood mononuclear cells (PBMCs) can profoundly influence T cell viability and immunogenicity. Gold-standard PBMC processing protocols have been developed by the Office of HIV/AIDS Network Coordination (HANC); however, these protocols are not universally observed. Herein, we have explored the current literature assessing how technical variation during PBMC processing can influence cellular viability and T cell immunogenicity, noting inconsistent findings between many of these studies. Amid the mounting concerns over scientific replicability, there is growing acknowledgement that improved methodological rigour and transparent reporting is required to facilitate independent reproducibility. This review highlights that in human T cell studies, this entails adopting stringent standardised operating procedures (SOPs) for PBMC processing. We specifically propose the use of HANC's Cross-Network PBMC Processing SOP, when collecting and cryopreserving PBMCs, and the HANC member network International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) PBMC Thawing SOP when thawing PBMCs. These stringent and detailed protocols include comprehensive reporting procedures to document unavoidable technical variations, such as delayed processing times. Additionally, we make further standardisation and reporting recommendations to minimise and document variability during this critical experimental period. This review provides a detailed overview of the challenges inherent to a procedure often considered routine, highlighting the importance of carefully considering each aspect of SOPs for PBMC collection, cryopreservation, thawing, and culture to ensure accurate interpretation and comparison between studies.

Multiparameter Flow Cytometry Monitoring of T Cell Responses

Multiparameter flow cytometry is a common tool for assessing responses of T, B, and other cells to pathogens or vaccines. Such responses are likely to be important for predicting the efficacy of an HIV vaccine, despite the elusive findings in HIV vaccine trials to date. Fortunately, flow cytometry has evolved to be capable of readily measuring 30-40 parameters, providing the ability to dissect detailed phenotypes and functions that may be correlated with disease protection. Nevertheless, technical hurdles remain, and standardization of assays is still largely lacking. Here an optimized protocol for antigen-specific T cell monitoring is presented, with specific variations for particular markers. It covers the analysis of multiple cytokines, cell surface proteins, and other functional markers such as CD107, CD154, CD137, etc. References are given to published panels of 8-28 colors.

Peripheral blood mononuclear cell mitochondrial dysfunction in acute alcohol-associated hepatitis

BACKGROUND

Patients with acute alcohol-associated hepatitis (AH) have immune dysfunction. Mitochondrial function is critical for immune cell responses and regulates senescence. Clinical translational studies using complementary bioinformatics-experimental validation of mitochondrial responses were performed in peripheral blood mononuclear cells (PBMC) from patients with AH, healthy controls (HC), and heavy drinkers without evidence of liver disease (HD).

METHODS

Feature extraction for differentially expressed genes (DEG) in mitochondrial components and telomere regulatory pathways from single-cell RNAseq (scRNAseq) and integrated 'pseudobulk' transcriptomics from PBMC from AH and HC (n = 4 each) were performed. After optimising isolation and processing protocols for functional studies in PBMC, mitochondrial oxidative responses to substrates, uncoupler, and inhibitors were quantified in independent discovery (AH n = 12; HD n = 6; HC n = 12) and validation cohorts (AH n = 10; HC n = 7). Intermediary metabolites (gas-chromatography/mass-spectrometry) and telomere length (real-time PCR) were quantified in subsets of subjects (PBMC/plasma AH n = 69/59; HD n = 8/8; HC n = 14/27 for metabolites; HC n = 13; HD n = 8; AH n = 72 for telomere length).

RESULTS

Mitochondrial, intermediary metabolite, and senescence-regulatory genes were differentially expressed in PBMC from AH and HC in a cell type-specific manner at baseline and with lipopolysaccharide (LPS). Fresh PBMC isolated using the cell preparation tube generated optimum mitochondrial responses. Intact cell and maximal respiration were lower (p ≤ .05) in AH than HC/HD in the discovery and validation cohorts. In permeabilised PBMC, maximum respiration, complex I and II function were lower in AH than HC. Most tricarboxylic acid (TCA) cycle intermediates in plasma were higher while those in PBMC were lower in patients with AH than those from HC. Lower telomere length, a measure of cellular senescence, was associated with higher mortality in AH.

CONCLUSION

Patients with AH have lower mitochondrial oxidative function, higher plasma TCA cycle intermediates, with telomere shortening in nonsurvivors.

Assessment of a multisite standardized biospecimen collection protocol for immune phenotyping in neurodevelopmental disorders

Multisite collection and preservation of peripheral blood mononuclear cells (PBMCs) for centralized analysis is an indispensable strategy for large cohort immune phenotyping studies. However, the absence of cross-site standardized protocols introduces unnecessary sample variance. Here we describe the protocol implemented by the Province of Ontario Neurodevelopmental Disorders (POND) Network's immune platform for the multisite collection, processing, and cryopreservation of PBMCs. We outline quality control standards and evaluate the performance of our PBMC processing and storage protocol. We also describe the Child Immune History Questionnaire results, an assessment tool evaluating pre-existing immune conditions in children with neurodevelopmental disorders (NDDs). Cell viability was assessed in samples from 178 participants based on strict quality control criteria. Overall, 83.1% of samples passed quality control standards. Samples collected and processed at the same site had higher quality control pass rates than samples that were collected and subsequently shipped to another site for processing. We investigated if freezer time impacted sample viability and found no difference in mean freezer time between samples that passed and failed quality control. The Child Immune History Questionnaire had a response rate of 87.1%. The described protocol produces viable samples that may be used in future immune phenotyping experiments.

Evaluation of Cellular Immune Response to Adeno-Associated Virus-Based Gene Therapy

The number of approved or investigational late phase viral vector gene therapies (GTx) has been rapidly growing. The adeno-associated virus vector (AAV) technology continues to be the most used GTx platform of choice. The presence of pre-existing anti-AAV immunity has been firmly established and is broadly viewed as a potential deterrent for successful AAV transduction with a possibility of negative impact on clinical efficacy and a connection to adverse events. Recommendations for the evaluation of humoral, including neutralizing and total antibody based, anti-AAV immune response have been presented elsewhere. This manuscript aims to cover considerations related to the assessment of anti-AAV cellular immune response, including review of correlations between humoral and cellular responses, potential value of cellular immunogenicity assessment, and commonly used analytical methodologies and parameters critical for monitoring assay performance. This manuscript was authored by a group of scientists involved in GTx development who represent several pharma and contract research organizations. It is our intent to provide recommendations and guidance to the industry sponsors, academic laboratories, and regulatory agencies working on AAV-based GTx viral vector modalities with the goal of achieving a more consistent approach to anti-AAV cellular immune response assessment.

Validation of the performance and suitability of a new class of FBS optimized for use in single-cell functional assays

The use of conventional serum for supplementation of media in cell-based and single-cell functional assays has been a major challenge for assay performance, standardization, optimization, and reproducibility. It has been identified as the leading cause of variability and suboptimal performance in large, international Elispot proficiency panels (Janetzki et al., 2008; Rountree et al., 2016). Extensive pretesting and optimization activities are one approach to overcome these challenges, but they are time-consuming and resource-intensive because suitable lots of serum are difficult to identify and secure in sufficient quantities to provide stability in long-term studies. Advancements in manufacturing methods have resulted in a new class of serum with the potential to solve these challenges. An IFNɣ Elispot study was designed by the External Quality Assurance Program Oversight Laboratory (EQAPOL) at Duke Human Vaccine Institute's (DHVI) Immunology and Virology Quality Assessment Center (IVQAC) to test this new class of serum against their in-house, validated control serum, which is regarded as a global standard in performance for high functionality, recovery, and viability. Commonly used serum-free media were also included in the study. The results of this study compellingly demonstrate that this new class of serum produces high responses and low background reactivity comparable to the included serum standard, with excellent recovery and viability of cells. A protocol for ongoing testing has been developed to continuously validate new batches of this serum with the goal to make available to the field a pretested and validated serum that can be used with confidence in functional cell-based assays.

Qualification of Hemophilia Treatment Centers to Enable Multi-Center Studies of Gene Expression Signatures in Blood Cells from Pediatric Patients

Hemophilia A is a rare congenital bleeding disorder caused by a deficiency of functionally active coagulation factor VIII (FVIII). Most patients with the severe form of the disease require FVIII replacement therapies, which are often associated with the development of neutralizing antibodies against FVIII. Why some patients develop neutralizing antibodies while others do not is not fully understood. Previously, we could demonstrate that the analysis of FVIII-induced gene expression signatures in peripheral blood mononuclear cells (PBMC) obtained from patients exposed to FVIII replacement therapies provides novel insights into underlying immune mechanisms regulating the development of different populations of FVIII-specific antibodies. The aim of the study described in this manuscript was the development of training and qualification test procedures to enable local operators in different European and US clinical Hemophilia Treatment Centers (HTC) to produce reliable and valid data for antigen-induced gene expression signatures in PBMC obtained from small blood volumes. For this purpose, we used the model antigen Cytomegalovirus (CMV) phosphoprotein (pp) 65. We trained and qualified 39 local HTC operators from 15 clinical sites in Europe and the US, of whom 31 operators passed the qualification at first attempt, and eight operators passed at the second attempt.

Safety and Outcomes of a Plasmid DNA Vaccine Encoding the ERBB2 Intracellular Domain in Patients With Advanced-Stage ERBB2-Positive Breast Cancer: A Phase 1 Nonrandomized Clinical Trial

Importance

High levels of ERBB2 (formerly HER2)-specific type 1 T cells in the peripheral blood are associated with favorable clinical outcomes after trastuzumab therapy; however, only a minority of patients develop measurable ERBB2 immunity after treatment. Vaccines designed to increase ERBB2-specific T-helper cells could induce ERBB2 immunity in a majority of patients.

Objective

To determine the safety and immunogenicity of 3 doses (10, 100, and 500 μg) of a plasmid-based vaccine encoding the ERBB2 intracellular domain (ICD).

Design, Setting, and Participants

Single-arm phase 1 trial including 66 patients with advanced-stage ERBB2-positive breast cancer treated in an academic medical center between 2001 and 2010 with 10-year postvaccine toxicity assessments. Data analysis was performed over 2 periods: January 2012 to March 2013 and July 2021 to August 2022.

Interventions

Patients were sequentially enrolled to the 3 dose arms. The vaccine was administered intradermally once a month with soluble granulocyte-macrophage colony-stimulating factor as an adjuvant for 3 immunizations. Toxicity evaluations occurred at set intervals and yearly. Peripheral blood mononuclear cells were collected for evaluation of immunity. Biopsy of vaccine sites at weeks 16 and 36 measured DNA persistence.

Main Outcomes and Measures

Safety was graded by Common Terminology Criteria for Adverse Events, version 3.0, and ERBB2 ICD immune responses were measured by interferon-γ enzyme-linked immunosorbent spot. Secondary objectives determined if vaccine dose was associated with immunity and evaluated persistence of plasmid DNA at the vaccine site.

Results

A total of 66 patients (median [range] age, 51 [34-77] years) were enrolled. The majority of vaccine-related toxic effects were grade 1 and 2 and not significantly different between dose arms. Patients in arm 2 (100 μg) and arm 3 (500 μg) had higher magnitude ERBB2 ICD type 1 immune responses at most time points than arm 1 (10 μg) (arm 2 compared with arm 1, coefficient, 181 [95% CI, 60-303]; P = .003; arm 3 compared with arm 1, coefficient, 233 [95% CI, 102-363]; P < .001) after adjusting for baseline factors. ERBB2 ICD immunity at time points after the end of immunizations was significantly lower on average in patients with DNA persistence at week 16 compared with those without persistence. The highest vaccine dose was associated with the greatest incidence of persistent DNA at the injection site.

Conclusions and Relevance

In this phase 1 nonrandomized clinical trial, immunization with the 100-μg dose of the ERBB2 ICD plasmid-based vaccine was associated with generation of ERBB2-specific type 1 T cells in most patients with ERBB2-expressing breast cancer, and it is currently being evaluated in randomized phase 2 trials.

Trial Registration

ClinicalTrials.gov Identifier: NCT00436254.

Optimizing an immunomodulatory potency assay for Mesenchymal Stromal Cell

The expeditious progress of Mesenchymal Stromal Cells (MSC) for therapeutic intervention calls for means to compare differences in potency of cell products. The differences may be attributed to innumerable sources including tissue origin, production methods, or even between batches. While the immunomodulatory potential of MSC is recognized and well-documented by an expansive body of evidence, the methodologies and findings vary markedly. In this study, we utilized flowcytometric analysis of lymphocyte proliferation based on cryopreserved peripheral blood mononuclear cells for quantification of the inhibitory effect of MSC. Technical aspects of fluorescent staining and cryopreservation of peripheral blood mononuclear cells were evaluated to obtain optimal results and increase feasibility. A range of common specific and unspecific mitogens was titrated to identify the conditions, in which the effects of Adipose tissue-derived Stromal Cells (ASC; a type of MSC) were most pronounced. Specific stimulation by antibody-mediated activation of CD3 and CD28 via TransAct and Dynabeads lead to substantial proliferation of lymphocytes, which was inhibited by ASC. These results were closely mirrored when applying unspecific stimulation in form of phytohemagglutinin (PHA), but not concanavalin A or pokeweed mitogen. The mixed lymphocyte reaction is a common assay which exploits alloreactivity between donors. While arguably more physiologic, the output of the assay often varies substantially, and the extent of proliferation is limited since the frequency of alloreactive cells is low, as opposed to the mitogens. To heighten the proliferative response and robustness, combinations of 2-5 donors were tested. Maximum proliferation was observed when combining 4 or more donors, which was efficiently suppressed by ASC. Several desirable and unfavorable traits can be attributed to the tested stimuli in the form of keywords. The importance of these traits should be scored on a laboratory-level to identify the ideal mitogen. In our case the ranking listed PHA as the most suited candidate. Developing robust assays is no trivial feat. By disclosing the full methodological framework in the present study, we hope to aid others in establishing functional metrics on the road to potency assays.

Novel peptide-based vaccine targeting heat shock protein 90 induces effective antitumor immunity in a HER2+ breast cancer murine model

Background

Heat shock protein 90 (HSP90) is a protein chaperone for most of the important signal transduction pathways in human epidermal growth factor receptor 2-positive (HER2+) breast cancer, including human epidermal growth factor receptor 2, estrogen receptor, progesterone receptor and Akt. The aim of our study is to identify peptide-based vaccines and to develop an effective immunotherapeutics for the treatment of HER2+ breast cancer.

Methods

HSP90-derived major histocompatibility complex (MHC) class II epitopes were selected using in silico algorithms and validated by enzyme-linked immunospot (ELISPOT). In vivo antitumor efficacy was evaluated in MMTVneu-transgenic mice. HSP90 peptide-specific systemic T-cell responses were assessed using interferon gamma ELISPOT assay, and immune microenvironment in tumors was evaluated using multiplex immunohistochemistry and TCRβ sequencing.

Results

First, candidate HSP90-derived MHC class II epitopes with high binding affinities across multiple human HLA class II genotypes were identified using in silico algorithms. Among the top 10 peptides, p485 and p527 were selected as promising Th1 immunity-inducing epitopes with low potential for Th2 immunity induction. The selected MHC class II HSP90 peptides induced strong antigen-specific T cell responses, which was induced by cross-priming of CD8⁺ T cells in vivo. The HSP90 peptide vaccines were effective in the established tumor model, and their efficacy was further enhanced when combined with stimulator of interferon genes (STING) agonist and/or anticytotoxic T lymphocyte-associated antigen-4 antibody in MMTVneu-transgenic mice. Increased tumor rejection was associated with increased systemic HSP90-specific T-cell responses, increased T-cell recruitment in tumor microenvironment, intermolecular epitope spreading, and increased rearrangement of TCRβ by STING agonist.

Conclusions

In conclusion, we have provided the first preclinical evidence of the action mechanism of HSP90 peptide vaccines with a distinct potential for improving breast cancer treatment.

Anti-tumor activity of a T-helper 1 multiantigen vaccine in a murine model of prostate cancer

Prostate cancer is one of the few malignancies that includes vaccination as a treatment modality. Elements of an effective cancer vaccine should include the ability to elicit a Type I T-cell response and target multiple antigenic proteins expressed early in the disease. Using existing gene datasets encompassing normal prostate tissue and tumors with Gleason Score ≤ 6 and ≥ 8, 10 genes were identified that were upregulated and conserved in prostate cancer regardless of the aggressiveness of disease. These genes encoded proteins also expressed in prostatic intraepithelial neoplasia. Putative Class II epitopes derived from these proteins were predicted by a combination of algorithms and, using human peripheral blood, epitopes which selectively elicited IFN-γ or IL-10 dominant antigen specific cytokine secretion were determined. Th1 selective epitopes were identified for eight antigens. Epitopes from three antigens elicited Th1 dominant immunity in mice; PSMA, HPN, and AMACR. Each single antigen vaccine demonstrated significant anti-tumor activity inhibiting growth of implanted Myc-Cap cells after immunization as compared to control. Immunization with the combination of antigens, however, was superior to each alone in controlling tumor growth. When vaccination occurred simultaneously to tumor implant, multiantigen immunized mice had significantly smaller tumors than controls (p = 0.002) and a significantly improved overall survival (p = 0.0006). This multiantigen vaccine shows anti-tumor activity in a murine model of prostate cancer.

Rules of thumb to obtain, isolate, and preserve porcine peripheral blood mononuclear cells

One of the most used biospecimens in immunology are peripheral blood mononuclear cells (PBMC). PBMC are particularly useful when evaluating immunity through responses of circulating B- and T-cells, during an infection, or after a vaccination. While several reviews and research papers have been published aiming to point out critical steps when sampling, isolating, and cryopreserving human PBMC -or even analyzing any parameter before sampling that could impair the immune assays' outcomes-, there are almost no publications in swine research dealing with these topics. As it has been demonstrated, several factors, such as stress, circadian rhythmicity, or the anticoagulant used have serious negative impact, not only on the separation performance of PBMC, but also on the ulterior immune assays. The present review aims to discuss studies carried out in humans that could shed some light for swine research. When possible, publications in pigs are also discussed. The main goal of the review is to encourage swine researchers to standardize protocols to obtain, manage and preserve porcine PBMC, as well as to minimize, or at least to consider, the bias that some parameters might induce in their studies before, during and after isolating PBMC.

Immunization with a Plasmid DNA Vaccine Encoding the N-Terminus of Insulin-like Growth Factor Binding Protein-2 in Advanced Ovarian Cancer Leads to High-level Type I Immune Responses

BACKGROUND

Cancer vaccines targeting nonmutated proteins elicit limited type I T-cell responses and can generate regulatory and type II T cells. Class II epitopes that selectively elicit type I or type II cytokines can be identified in nonmutated cancer-associated proteins. In mice, a T-helper I (Th1) selective insulin-like growth factor binding protein-2 (IGFBP-2) N-terminus vaccine generated high levels of IFNγ secreting T cells, no regulatory T cells, and significant antitumor activity. We conducted a phase I trial of T-helper 1 selective IGFBP-2 vaccination in patients with advanced ovarian cancer.

METHODS

Twenty-five patients were enrolled. The IGFBP-2 N-terminus plasmid-based vaccine was administered monthly for 3 months. Toxicity was graded by NCI criteria and antigen-specific T cells measured by IFNγ/IL10 ELISPOT. T-cell diversity and phenotype were assessed.

RESULTS

The vaccine was well tolerated, with 99% of adverse events graded 1 or 2, and generated high levels of IGFBP-2 IFNγ secreting T cells in 50% of patients. Both Tbet⁺ CD4 (P = 0.04) and CD8 (P = 0.007) T cells were significantly increased in immunized patients. There was no increase in GATA3⁺ CD4 or CD8, IGFBP-2 IL10 secreting T cells, or regulatory T cells. A significant increase in T-cell clonality occurred in immunized patients (P = 0.03, pre- vs. post-vaccine) and studies showed the majority of patients developed epitope spreading within IGFBP-2 and/or to other antigens. Vaccine nonresponders were more likely to have preexistent IGFBP-2 specific immunity and demonstrated defects in CD4 T cells, upregulation of PD-1, and downregulation of genes associated with T-cell activation, after immunization.

CONCLUSIONS

IGFBP-2 N-terminus Th1 selective vaccination safely induces type I T cells without evidence of regulatory responses.

Panel Optimization for High-Dimensional Immunophenotyping Assays Using Full-Spectrum Flow Cytometry

Technological advancements in fluorescence flow cytometry and an ever-expanding understanding of the complexity of the immune system have led to the development of large flow cytometry panels reaching up to 43 colors at the single-cell level. However, as panel size and complexity increase, so too does the detail involved in designing and optimizing successful high-quality panels fit for downstream high-dimensional data analysis. In contrast to conventional flow cytometers, full-spectrum flow cytometers measure the entire emission spectrum of each fluorophore across all lasers. This allows for fluorophores with very similar emission maxima but unique overall spectral fingerprints to be used in conjunction, enabling relatively straightforward design of larger panels. Although a protocol for best practices in full-spectrum flow cytometry panel design has been published, there is still a knowledge gap in going from the theoretically designed panel to the necessary steps required for panel optimization. Here, we aim to guide users through the theory of optimizing a high-dimensional full-spectrum flow cytometry panel for immunophenotyping using comprehensive step-by-step protocols. These protocols can also be used to troubleshoot panels when issues arise. A practical application of this approach is exemplified with a 24-color panel designed for identification of conventional T-cell subsets in human peripheral blood. © 2021 Malaghan Institute of Medical Research, Cytek Biosciences. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Preparation and evaluation of optimal spectral reference controls Support Protocol 1: Antibody titration Support Protocol 2: Changing instrument settings Basic Protocol 2: Unmixing evaluation of fully stained sample Basic Protocol 3: Evaluation of marker resolution Support Protocol 3: Managing heterogeneous autofluorescence Basic Protocol 4: Assessment of data quality using expert gating and dimensionality reduction algorithms.

Multi-Epitope-Based Vaccines for Colon Cancer Treatment and Prevention

Background

Overexpression of nonmutated proteins involved in oncogenesis is a mechanism by which such proteins become immunogenic. We questioned whether overexpressed colorectal cancer associated proteins found at higher incidence and associated with poor prognosis could be effective vaccine antigens. We explored whether vaccines targeting these proteins could inhibit the development of intestinal tumors in the azoxymethane (AOM)-induced colon model and APC Min mice.

Methods

Humoral immunity was evaluated by ELISA. Web-based algorithms identified putative Class II binding epitopes of the antigens. Peptide and protein specific T-cells were identified from human peripheral blood mononuclear cells using IFN-gamma ELISPOT. Peptides highly homologous between mouse and man were formulated into vaccines and tested for immunogenicity in mice and in vivo tumor challenge. Mice treated with AOM and APC Min transgenic mice were vaccinated and monitored for tumors.

Results

Serum IgG for CDC25B, COX2, RCAS1, and FASCIN1 was significantly elevated in colorectal cancer patient sera compared to volunteers (CDC25B p=0.002, COX-2 p=0.001, FASCIN1 and RCAS1 p<0.0001). Epitopes predicted to bind to human class II MHC were identified for each protein and T-cells specific for both the peptides and corresponding recombinant protein were generated from human lymphocytes validating these proteins as human antigens. Some peptides were highly homologous between mouse and humans and after immunization, mice developed both peptide and protein specific IFN-γ-secreting cell responses to CDC25B, COX2 and RCAS1, but not FASCIN1. FVB/nJ mice immunized with CDC25B or COX2 peptides showed significant inhibition of growth of the syngeneic MC38 tumor compared to control (p<0.0001). RCAS1 peptide vaccination showed no anti-tumor effect. In the prophylactic setting, after immunization with CDC25B or COX2 peptides mice treated with AOM developed significantly fewer tumors as compared to controls (p<0.0002) with 50% of mice remaining tumor free in each antigen group. APC Min mice immunized with CDC25B or COX2 peptides developed fewer small bowel tumors as compared to controls (p=0.01 and p=0.02 respectively).

Conclusions

Immunization with CDC25B and COX2 epitopes consistently suppressed tumor development in each model evaluated. These data lay the foundation for the development of multi-antigen vaccines for the treatment and prevention of colorectal cancer.

Optimization of Blood Handling and Peripheral Blood Mononuclear Cell Cryopreservation of Low Cell Number Samples

Background: Rural/remote blood collection can cause delays in processing, reducing PBMC number, viability, cell composition and function. To mitigate these impacts, blood was stored at 4 °C prior to processing. Viable cell number, viability, immune phenotype, and Interferon-γ (IFN-γ) release were measured. Furthermore, the lowest protective volume of cryopreservation media and cell concentration was investigated. Methods: Blood from 10 individuals was stored for up to 10 days. Flow cytometry and IFN-γ ELISPOT were used to measure immune phenotype and function on thawed PBMC. Additionally, PBMC were cryopreserved in volumes ranging from 500 µL to 25 µL and concentration from 10 × 10⁶ cells/mL to 1.67 × 10⁶ cells/mL. Results: PBMC viability and viable cell number significantly reduced over time compared with samples processed immediately, except when stored for 24 h at RT. Monocytes and NK cells significantly reduced over time regardless of storage temperature. Samples with >24 h of RT storage had an increased proportion in Low-Density Neutrophils and T cells compared with samples stored at 4 °C. IFN-γ release was reduced after 24 h of storage, however not in samples stored at 4 °C for >24 h. The lowest protective volume identified was 150 µL with the lowest density of 6.67 × 10⁶ cells/mL. Conclusion: A sample delay of 24 h at RT does not impact the viability and total viable cell numbers. When long-term delays exist (>4 d) total viable cell number and cell viability losses are reduced in samples stored at 4 °C. Immune phenotype and function are slightly altered after 24 h of storage, further impacts of storage are reduced in samples stored at 4 °C.

IL-5 mediates monocyte phenotype and pain outcomes in fibromyalgia

ABSTRACT

Fibromyalgia (FM) is characterized by widespread chronic pain, fatigue, and somatic symptoms. The influence of phenotypic changes in monocytes on symptoms associated with FM is not fully understood. The primary aim of this study was to take a comprehensive whole-body to molecular approach in characterizing relationships between monocyte phenotype and FM symptoms in relevant clinical populations. Lipopolysaccharide-evoked and spontaneous secretion of IL-5 and other select cytokines from circulating monocytes was higher in women with FM compared to women without pain. In addition, greater secretion of IL-5 was significantly associated with pain and other clinically relevant psychological and somatic symptoms of FM. Furthermore, higher levels of pain and pain-related symptoms were associated with a lower percentage of intermediate monocytes (CD14++/CD16+) and a greater percentage of nonclassical monocytes (CD14+/CD16++) in women with FM. Based on findings from individuals with FM, we examined the role of IL-5, an atypical cytokine secreted from monocytes, in an animal model of widespread muscle pain. Results from the animal model show that IL-5 produces analgesia and polarizes monocytes toward an anti-inflammatory phenotype (CD206+). Taken together, our data suggest that monocyte phenotype and their cytokine profiles are associated with pain-related symptoms in individuals with FM. Furthermore, our data show that IL-5 has a potential role in analgesia in an animal model of FM. Thus, targeting anti-inflammatory cytokines such as IL-5 secreted by circulating leukocytes could serve as a promising intervention to control pain and other somatic symptoms associated with FM.

A guide to investigating immune responses elicited by whole-sporozoite pre-erythrocytic vaccines against malaria

In the last few decades, considerable efforts have been made toward the development of efficient vaccines against malaria. Whole-sporozoite (Wsp) vaccines, which induce efficient immune responses against the pre-erythrocytic (PE) stages (sporozoites and liver forms) of Plasmodium parasites, the causative agents of malaria, are among the most promising immunization strategies tested until present. Several Wsp PE vaccination approaches are currently under evaluation in the clinic, including radiation- or genetically-attenuated Plasmodium sporozoites, live parasites combined with chemoprophylaxis, or genetically modified rodent Plasmodium parasites. In addition to the assessment of their protective efficacy, clinical trials of Wsp PE vaccine candidates inevitably involve the thorough investigation of the immune responses elicited by vaccination, as well as the identification of correlates of protection. Here, we review the main methodologies employed to dissect the humoral and cellular immune responses observed in the context of Wsp PE vaccine clinical trials and discuss future strategies to further deepen the knowledge generated by these studies, providing a toolbox for the in-depth analysis of vaccine-induced immunogenicity.

A field method for cryopreservation of whole blood from a finger prick for later analysis with flow cytometry

OBJECTIVES

Flow cytometry is a powerful tool for investigating immune function, allowing for the quantification of leukocytes by subtype. Yet it has not been used extensively for field work due to perishable reagents and the need for immediate analysis of samples. To make flow cytometry more accessible, we devise and evaluate a field protocol for freezing capillary blood.

MATERIALS AND METHODS

We collected finger prick blood samples from 110 volunteers, age 18 to 42. Blood samples were analyzed immediately for 18 cell surface markers. Aliquots of whole blood were frozen in the vapor phase of a liquid nitrogen tank with 10% dimethyl sulfoxide in medium. Samples were analyzed on a Guava EasyCyte HT flow cytometer after 2, 4, or 14 weeks.

RESULTS

Major lymphocyte fractions in frozen samples were correlated with fresh values (T-cells: r = 0.82; Natural Killer [NK] cells: r = 0.64; CD4: r = 0.67; CD8: r = 0.82; Naïve CD4: r = 0.73, Naïve CD8: r = 0.71; B-cells: r = 0.73; all p < 0.001), and mean values were similar to those from fresh samples. However, correlations for smaller subsets of CD4 and B cells were generally poor. Some differences resulted from changes in non-specific binding for some antibody-conjugate pairs. Cryopreservation also resulted in a reduction in granulocytes more than lymphocytes.

DISCUSSION

Our results suggest that antibody/fluorochrome combinations should be validated before use on frozen samples, and that functional changes in cells may affect some cell markers. However, this simple freezing protocol utilizing finger pricks, whole blood, and a liquid nitrogen shipping tank is viable for obtaining samples for flow cytometry under field conditions.

Impact of 12-month cryopreservation on endogenous DNA damage in whole blood and isolated mononuclear cells evaluated by the comet assay

The comet assay is an electrophoretic technique used to assess DNA damage, as a marker of genotoxicity and oxidative stress, in tissues and biological samples including peripheral blood mononuclear cells (PBMCs) and whole blood (WB). Although numerous studies are performed on stored samples, the impact of cryopreservation on artifactual formation of DNA damage is not widely considered. The present study aims to evaluate the impact of storage at different time-points on the levels of strand breaks (SBs) and formamidopyrimidine DNA glycosylase (Fpg)-sensitive sites in isolated PBMCs and WB. Samples were collected, aliquoted and stored at − 80 °C. DNA damage was analyzed on fresh samples, and subsequently on frozen samples every 2 months up to a year. Results have shown no changes in DNA damage in samples of PBMCs and WB stored for up to 4 months, while a significant increase in SBs and Fpg-sensitive sites was documented starting from 6-month up to 12-month storage of both the samples. In addition, fresh and frozen WB showed higher basal levels of DNA damage compared to PBMCs. In conclusion, WB samples show high levels of DNA damage compared to PBMCs. One-year of storage increased the levels of SBs and Fpg-sensitive sites especially in the WB samples. Based on these findings, the use of short storage times and PBMCs should be preferred because of low background level of DNA damage in the comet assay.

Effect of serum replacement on murine spermatogonial stem cell cryopreservation

Cryopreservation of spermatogonial stem cells (SSCs) is a necessity to preserve the genetic information of valuable livestock herds and to produce transgenic animals. However, serum, a key component that allows efficient cryopreservation, has many limitations attributed to its undefined composition, inter-batch variations, and contamination potential. Therefore, we aimed to establish a method for serum-free cryopreservation of SSCs. To evaluate the cryopreservation efficiency of serum replacements, we assessed the recovery rate, relative proliferation potential, proliferation capacity, and apoptosis capacity. SSCs were characterized, and their functional activity was determined through immunofluorescence, RT-qPCR, and spermatogonial transplantation. The efficiency of each serum replacement was compared to that of the negative control (10% DMSO in DPBS) and positive control (10% DMSO and 40% FBS in DPBS). Our results indicated that cryopreservation with 5% human serum albumin (rHSA) exhibited a higher relative proliferation potential (274.0 ± 13.4%) than with DMSO control (100 ± 8.6%), with no significant difference from the 40% FBS (190.0 ± 20.1%). Moreover, early apoptosis also significantly decreased to a greater extent with 5% rHSA (5.1 ± 0.7%) than with DMSO control (12.9 ± 0.8%) and was at a level comparable to the 40% FBS (4.9 ± 0.8%). In addition, the SSCs cryopreserved with 5% rHSA exhibited normal self-renewal and differentiation abilities. In conclusion, 5% rHSA is a potential serum replacement for SSC cryopreservation, with properties comparable to that of serum. These results would contribute to the application of SSCs in improving livestock and in future clinical trials for human infertility treatment.

Decreased expression of transmembrane TNFR2 in lung leukocytes subpopulations of patients with non-fibrotic hypersensitivity pneumonitis compared with the fibrotic disease

Hypersensitivity pneumonitis (HP) is an interstitial lung disease, characterized by lung inflammation (non-fibrotic HP) that may often progresses to fibrosis (Fibrotic HP). The tumor necrosis factor (TNF) and its receptors (TNFR1 and TNFR2) can be found as soluble (sol) and transmembrane (tm) forms, playing pro-inflammatory functions but also has been related to immune regulatory functions. Bronchioalveolar lavage from fibrotic and non-fibrotic HP patients was obtained, and immune cells were characterized by flow cytometry, whereas soluble proteins were analyzed by ELISA. Compare to fibrotic HP patients, HP patients with non-fibrotic disease have accumulation of pro-inflammatory CD3+ myeloid cells, cell subpopulations that have decreased tmTNFR2 expression, and low frequency of regulatory-T cells. Whereas solTNF, solTNFR2, and IL-8 are increased. These findings suggest that the TNF pathway may explain, at least partially, the differences between both HP clinical forms. The evaluation of the TNF family molecules may help to develop new therapeutic approaches.

Functional comparison of PBMCs isolated by Cell Preparation Tubes (CPT) vs. Lymphoprep Tubes

Background

Cryopreserved human peripheral blood mononuclear cells (PBMCs) are a commonly used sample type for a variety of immunological assays. Many factors can affect the quality of PBMCs, and careful consideration and validation of an appropriate PBMC isolation and cryopreservation method is important for well-designed clinical studies. A major point of divergence in PBMC isolation protocols is the collection of blood, either directly into vacutainers pre-filled with density gradient medium or the use of conical tubes containing a porous barrier to separate the density gradient medium from blood. To address potential differences in sample outcome, we isolated, cryopreserved, and compared PBMCs using parallel protocols differing only in the use of one of two common tube types for isolation.

Methods

Whole blood was processed in parallel using both Cell Preparation Tubes™ (CPT, BD Biosciences) and Lymphoprep™ Tubes (Axis-Shield) and assessed for yield and viability prior to cryopreservation. After thawing, samples were further examined by flow cytometry for cell yield, cell viability, frequency of 10 cell subsets, and capacity for stimulation-dependent CD4+ and CD8+ T cell intracellular cytokine production.

Results

No significant differences in cell recovery, viability, frequency of immune cell subsets, or T cell functionality between PBMC samples isolated using CPT or Lymphoprep tubes were identified.

Conclusion

CPT and Lymphoprep tubes are effective and comparable methods for PBMC isolation for immunological studies.

Application of the comet assay in human biomonitoring: An hCOMET perspective

The comet assay is a well-accepted biomonitoring tool to examine the effect of dietary, lifestyle, environmental and occupational exposure on levels of DNA damage in human cells. With such a wide range of determinants for DNA damage levels, it becomes challenging to deal with confounding and certain factors are inter-related (e.g. poor nutritional intake may correlate with smoking status). This review describes the effect of intrinsic (i.e. sex, age, tobacco smoking, occupational exposure and obesity) and extrinsic (season, environmental exposures, diet, physical activity and alcohol consumption) factors on the level of DNA damage measured by the standard or enzyme-modified comet assay. Although each factor influences at least one comet assay endpoint, the collective evidence does not indicate single factors have a large impact. Thus, controlling for confounding may be necessary in a biomonitoring study, but none of the factors is strong enough to be regarded a priori as a confounder. Controlling for confounding in the comet assay requires a case-by-case approach. Inter-laboratory variation in levels of DNA damage and to some extent also reproducibility in biomonitoring studies are issues that have haunted the users of the comet assay for years. Procedures to collect specimens, and their storage, are not standardized. Likewise, statistical issues related to both sample-size calculation (before sampling of specimens) and statistical analysis of the results vary between studies. This review gives guidance to statistical analysis of the typically complex exposure, co-variate, and effect relationships in human biomonitoring studies.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.

Guidelines for Gating Flow Cytometry Data for Immunological Assays

"Gating" refers to the selection of successive subpopulations of cells for analysis in flow cytometry. It is usually performed manually, based on expert knowledge of cell characteristics. However, there can be considerable disagreement in how gates should be applied, even between individuals experienced in the field. While clinical software often automates gating, and some guidelines do exist (especially for clinical assays), there are no comprehensive guidelines across the various types of immunological assays performed using flow cytometry. Here we attempt to provide such guidelines, focused on the most general and pervasive types of gates, why they are important, and what recommendations can be made regarding their use. We do so through the display of example data, collected by academic, government, and industry representatives. These guidelines should be of value to both novice and experienced flow cytometrists analyzing a wide variety of immunological assays.

A standardized immune phenotyping and automated data analysis platform for multicenter biomarker studies

The analysis and validation of flow cytometry-based biomarkers in clinical studies are limited by the lack of standardized protocols that are reproducible across multiple centers and suitable for use with either unfractionated blood or cryopreserved PBMCs. Here we report the development of a platform that standardizes a set of flow cytometry panels across multiple centers, with high reproducibility in blood or PBMCs from either healthy subjects or patients 100 days after hematopoietic stem cell transplantation. Inter-center comparisons of replicate samples showed low variation, with interindividual variation exceeding inter-center variation for most populations (coefficients of variability <20% and interclass correlation coefficients >0.75). Exceptions included low-abundance populations defined by markers with indistinct expression boundaries (e.g., plasmablasts, monocyte subsets) or populations defined by markers sensitive to cryopreservation, such as CD62L and CD45RA. Automated gating pipelines were developed and validated on an independent data set, revealing high Spearman's correlations (rs >0.9) with manual analyses. This workflow, which includes pre-formatted antibody cocktails, standardized protocols for acquisition, and validated automated analysis pipelines, can be readily implemented in multicenter clinical trials. This approach facilitates the collection of robust immune phenotyping data and comparison of data from independent studies.

Susceptibility of A. fumigatus-specific T-cell assays to pre-analytic blood storage and PBMC cryopreservation greatly depends on readout platform and analytes

Mould-specific T cells detectable by flow cytometry or ELISPOT were proposed as a novel biomarker in invasive aspergillosis. To define protocols facilitating sample shipment and longitudinal analysis, this study evaluated the susceptibility of different functional assays for A. fumigatus-specific T-cell quantification and characterisation to pre-analytic delays. PBMCs from 6 healthy donors were analysed after immediate isolation, after 6 hours whole blood storage or after cryopreservation using 3 different common media. Functional responses to A. fumigatus lysate stimulation were comparatively assessed by flow cytometry, ELISPOT and 14-plex cytokine assay. After 6 hours pre-analytic storage, all functional assays showed reduced detection rates, higher coefficients of variation (CV) and widely varying individual recovery indices of specific T-cell response. While cryopreservation resulted in sufficient yields and largely unaltered cellular composition, outcomes of functional readouts significantly differed from freshly processed samples. For CD154-based flow cytometry, only cryopreservation in RPMI supplemented with autologous serum resulted in satisfactory detection rates and CVs. For ELISPOT and cytokine secretion assays, none of the cryopreservation protocols provided sufficient concordance with immediately processed samples. Even using the same readout platform, individual analytes widely varied in their susceptibility to cryopreservation, highlighting that distinct optimisation is required depending on the downstream assay.

Multiparameter Intracellular Cytokine Staining

Intracellular cytokine staining is a popular method for visualizing cellular responses, most often T-cell responses to antigenic or mitogenic stimulation. It can be coupled with staining for other functional markers, such as upregulation of CD107 or CD154, as well as phenotypic markers that define specific cellular subsets, e.g., effector and memory T-cell compartments, NK cells, or monocytes. Recent advances in multicolor flow cytometry instrumentation and software have allowed the routine combination of 12 or more markers, creating some technical and analytical challenges along the way, and exposing a need for standardization in the field. Here, we will review best practices for antibody panel design and procedural variables for multicolor intracellular cytokine staining, and present an optimized protocol with variations designed for use with specific markers and sample types.

Understanding preanalytical variables and their effects on clinical biomarkers of oncology and immunotherapy

Identifying a suitable course of immunotherapy treatment for a given patient as well as monitoring treatment response is heavily reliant on biomarkers detected and quantified in blood and tissue biospecimens. Suboptimal or variable biospecimen collection, processing, and storage practices have the potential to alter clinically relevant biomarkers, including those used in cancer immunotherapy. In the present review, we summarize effects reported for immunologically relevant biomarkers and highlight preanalytical factors associated with specific analytical platforms and assays used to predict and gauge immunotherapy response. Given that many of the effects introduced by preanalytical variability are gene-, transcript-, and protein-specific, biospecimen practices should be standardized and validated for each biomarker and assay to ensure accurate results and facilitate clinical implementation of newly identified immunotherapy approaches.

TLR8 ligation induces apoptosis of monocytic myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) accumulate in tumors and the peripheral blood of cancer patients and demonstrate cancer-promoting activity across multiple tumor types. A limited number of agents are known to impact MDSC activity. TLR8 is expressed in myeloid cells. We investigated expression of TLR8 on MDSC and the effect of a TLR8 agonist, motolimod, on MDSC survival and function. TLR8 was highly expressed in monocytic MDSC (mMDSC) but absent in granulocytic MDSC (gMDSC). Treatment of human PBMC with motolimod reduced the levels of mMDSC in volunteers and cancer donors versus control (P < 0.001). Motolimod did not impact levels of gMDSC. The reduction of mMDSC was due to induced cell death by TLR8 ligation. Pretreatment of PBMC with a FAS neutralizing antibody inhibited motolimod-induced reduction of mMDSC (P < 0.001). Finally, we demonstrated that mMDSC impeded IL-2 secretion by CD3/CD28-activated T cells; IL-2 secretion was partially restored when cells were cocultured with motolimod (142 ± 36 pg/ml vs. 59 ± 13 pg/ml; P = 0.03). There is increasing evidence that MDSCs contribute to the progression of cancer by inhibiting tumor-directed T cells. TLR8 agonists may synergize with cancer immunotherapeutic approaches to enhance the antitumor effects of the adaptive immune response.

Optimizing recovery of frozen human peripheral blood mononuclear cells for flow cytometry

Introduction

Live peripheral blood mononuclear cells (PBMCs) can be frozen and thawed for later analyses by adding and removing a cryoprotectant, such as dimethyl sulfoxide (DMSO). Laboratories across the world use various procedures, but published evidence of optimal thawing procedures is scarce.

Materials and methods

PBMCs were separated from blood collected from healthy Danish blood donors, and stored at -80°C after adding of DMSO. The essential steps in the thawing procedure were modified and performance was evaluated by flow cytometry with respect to the percentage and total yield of viable PMBCs.

Results

The best-performing washing medium was Roswell Park Memorial Institute (RPMI) 1640 at 37°C with 20% fetal bovine serum. When using 10 mL washing medium in a 15-mL Falcon tube, samples should be centrifuged for at least 10 minutes at 500 g. We failed to detect any differences between the tested methods of mixing PBMCs with washing medium. Likewise, neither the thawing duration nor centrifugation temperature (20°C and 37°C) had any effect. PBMCs could be incubated (rested) for up to eight hours in a 37°C 5% CO₂ incubator without affecting cell counts, but incubating PBMCs for 16 hours significantly decreased viability and recovery. In general, high viability was not necessarily associated with high recovery.

Conclusion

Changing the thawing procedure significantly impacted PBMC viability and live cell recovery. Evaluating both viability and live PBMC recovery are necessary to evaluate method performance. Investigation of differential loss of PBMC subtypes and phenotypic changes during thawing and incubation requires further evaluation.

Serum C-Reactive Protein and Congestive Heart Failure as Significant Predictors of Herpes Zoster Vaccine Response in Elderly Nursing Home Residents

Background

Elderly long-term care residents often exhibit a myriad of risk factors for immune dysfunction, including chronic inflammation and multiple comorbid conditions, which undoubtedly contribute to their enhanced susceptibility to infection. Hence, understanding the factors required for optimal vaccine responsiveness is critical.

Methods

We examined 187 elderly nursing home residents (aged 80-102 years) and 50 community-dwelling seniors (aged 60-75 years) immunized with the live-attenuated varicella-zoster virus (VZV) vaccine. Specifically, we examined whether vaccine responsiveness was associated with serum C-reactive protein (CRP), tumor necrosis factor, interleukin 1β, 6, and 10, leukocyte telomere length, chronic disease status, and frailty.

Results

Elderly participants had significantly higher levels of CRP, tumor necrosis factor, and interleukin 6 and shorter leukocyte telomere length. Vaccine responsiveness was inversely related to the CRP level in elderly participants, but not seniors, and those with congestive heart failure were less likely to achieve a 2-fold response (odds ratio, 0.08). The latter relationship is probably due to immunosenescence, because heart failure was associated with increased senescent CD4+ T cells, and reduced naive and effector and central memory CD8+ T cells.

Conclusions

In summary, these data improve our understanding of vaccine responsiveness for those in long-term care, suggesting that certain risk factors are associated with a greater likelihood of vaccine failure.

Reconstitution of immune cell populations in multiple sclerosis patients after autologous stem cell transplantation

Multiple sclerosis is an inflammatory T cell-mediated autoimmune disease. In a Phase II clinical trial, high-dose immunosuppressive therapy combined with autologous CD34⁺ haematopoietic stem cell transplant resulted in 69·2% of subjects remaining disease-free without evidence of relapse, loss of neurological function or new magnetic resonance imaging (MRI) lesions to year 5 post-treatment. A combination of CyTOF mass cytometry and multi-parameter flow cytometry was used to explore the reconstitution kinetics of immune cell subsets in the periphery post-haematopoietic cell transplant (HSCT) and the impact of treatment on the phenotype of circulating T cells in this study population. Repopulation of immune cell subsets progressed similarly for all patients studied 2 years post-therapy, regardless of clinical outcome. At month 2, monocytes and natural killer (NK) cells were proportionally more abundant, while CD4 T cells and B cells were reduced, relative to baseline. In contrast to the changes observed at earlier time-points in the T cell compartment, B cells were proportionally more abundant and expansion in the proportion of naive B cells was observed 1 and 2 years post-therapy. Within the T cell compartment, the proportion of effector memory and late effector subsets of CD4 and CD8 T cells was increased, together with transient increases in proportions of CD45RA-regulatory T cells (T_regs ) and T helper type 1 (Th1 cells) and a decrease in Th17·1 cells. While none of the treatment effects studied correlated with clinical outcome, patients who remained healthy throughout the 5-year study had significantly higher absolute numbers of memory CD4 and CD8 T cells in the periphery prior to stem cell transplantation.

Immunization against HIF-1α Inhibits the Growth of Basal Mammary Tumors and Targets Mammary Stem Cells In Vivo

Purpose: Triple-negative breast cancer (TNBC) represents a cancer stem cell-enriched phenotype. Hypoxia-inducible factor-1α (HIF-1α) induces the expression of proteins associated with stemness and is highly upregulated in TNBC. We questioned whether HIF-1α was immunogenic and whether vaccination targeting HIF-1α would impact the growth of basal-like mammary tumors in transgenic mice.Experimental Design: We evaluated HIF-1α-specific IgG in sera from controls and patients with breast cancer. Class II epitopes derived from the HIF-1α protein sequence were validated by ELISPOT. To assess therapeutic efficacy, we immunized Tg-MMTVneu and C3(1)Tag mice with HIF-1α Th1-inducing peptides. Stem cells were isolated via magnetic bead separation. Levels of HIF-1α and stem cells in the tumor were quantitated by Western blotting and flow cytometry.Results: The magnitude (P < 0.001) and incidence (P < 0.001) of HIF-1α-specific IgG were elevated in TNBC patients compared with controls. Both breast cancer patients and donors showed evidence of HIF-1α-specific Th1 and Th2 immunity. Three HIF-1α-specific Th1 class II restricted epitopes that were highly homologous between species elicited type I immunity in mice. After HIF-1α vaccination, mammary tumor growth was significantly inhibited in only C3(1)Tag (basal-like/stem cell^high; P < 0.001) not TgMMTV-neu (luminal/neu/stem cell^low; P = 0.859) murine models. Vaccination increased type I T cells in the tumor (P = 0.001) and decreased cells expressing the stem cell marker, Sca-1, compared with controls (P = 0.004).Conclusions: An HIF-1α vaccine may be uniquely effective in limiting tumor growth in TNBC. Inhibiting outgrowth of breast cancer stem cells via active immunization in the adjuvant setting may impact disease recurrence. Clin Cancer Res; 23(13); 3396-404. ©2016 AACR.

Efficient Culture of Human Naive and Memory B Cells for Use as APCs

The ability to culture and expand B cells in vitro has become a useful tool for studying human immunity. A limitation of current methods for human B cell culture is the capacity to support mature B cell proliferation. We developed a culture method to support the efficient activation and proliferation of naive and memory human B cells. This culture supports extensive B cell proliferation, with ∼10³-fold increases following 8 d in culture and 10⁶-fold increases when cultures are split and cultured for 8 more days. In culture, a significant fraction of naive B cells undergo isotype switching and differentiate into plasmacytes. Culture-derived (CD) B cells are readily cryopreserved and, when recovered, retain their ability to proliferate and differentiate. Significantly, proliferating CD B cells express high levels of MHC class II, CD80, and CD86. CD B cells act as APCs and present alloantigens and microbial Ags to T cells. We are able to activate and expand Ag-specific memory B cells; these cultured cells are highly effective in presenting Ag to T cells. We characterized the TCR repertoire of rare Ag-specific CD4⁺ T cells that proliferated in response to tetanus toxoid (TT) presented by autologous CD B cells. TCR Vβ usage by TT-activated CD4⁺ T cells differs from resting and unspecifically activated CD4⁺ T cells. Moreover, we found that TT-specific TCR Vβ usage by CD4⁺ T cells was substantially different between donors. This culture method provides a platform for studying the BCR and TCR repertoires within a single individual.

Immunogenicity of Varicella Vaccine and Immunologic Predictors of Response in a Cohort of Elderly Nursing Home Residents

BACKGROUND

 Little is known about the immunogenicity of live-attenuated Oka/Merck varicella zoster virus (VZV)-containing vaccine (hereafter, "varicella vaccine") in frail nursing homes residents nor about immune phenotypes associated with a response.

METHODS

 A cohort of 190 frail nursing home residents aged 80-102 years and a cohort of 50 community-dwelling seniors aged 60-75 years (a comparison group) received varicella vaccine. Interferon γ (IFN-γ) enzyme-linked immunospot assays were performed before and 6 weeks after vaccination. Cellular markers of immunosenescence were measured in the nursing home elderly.

RESULTS

 The average number of IFN-γ spot-forming cells at baseline was significantly lower in the elderly nursing home residents than in the community-dwelling seniors. However, following vaccination, the VZV immune response increased in both cohorts, and no difference was noted in the fold difference of the response between the 2 cohorts. Upon further examination of the elderly nursing home residents, we found that higher frequencies of regulatory T cells and cytomegalovirus-specific CD4⁺ T cells correlated negatively with the magnitude of VZV-specific responses.

CONCLUSIONS

 The Oka/Merck varicella vaccine induces VZV immunity in elderly nursing home residents that is similar to that produced in community-dwelling seniors.

CLINICAL TRIALS REGISTRATION

 NCT01328548.

Effect of Japanese cedar-specific sublingual immunotherapy on allergen-specific TH2 cell counts in blood

BACKGROUND

The contribution of antigen-specific TH cells in peripheral blood to immunologic mechanisms underlying sublingual immunotherapy (SLIT) remains unclear, partly because of the lack of a standardized method for the analysis of this rare lymphocyte subset.

OBJECTIVE

To clarify the role of antigen-specific TH cells during SLIT using a sensitive method analyzing activation marker CD154-positive TH cells with multicolor flow cytometry.

METHODS

We assessed antigen-specific TH cells using multicolor flow cytometry based on the expression of the activation marker CD154 and intracellular cytokines in patients with Japanese cedar pollinosis receiving SLIT at baseline and during the first pollen season after the initiation of SLIT.

RESULTS

A total of 18 patients between 12 and 44 years of age were enrolled in the present study. Of these, 8 patients received SLIT (SLIT group) and 10 patients received symptomatic treatment only (control group). Although seasonal pollen exposure significantly increased the number of Japanese cedar-specific interleukin 5- and interleukin 4-producing TH cells in the control group (P < .01 for both), SLIT ameliorated this increase in the SLIT group (P = .64 and P = .84, respectively).

CONCLUSION

The present study indicates that allergen-specific TH2 cells in peripheral blood are involved in mechanisms underlying SLIT. The analysis of antigen-specific TH cells using multicolor flow cytometry based on the expression of the activation marker CD154 represents a sensitive and relatively simple, standardized method for monitoring peripheral antigen-specific TH cells during allergen-specific immunotherapy.

A novel method for evaluating antibody-dependent cell-mediated cytotoxicity by flowcytometry using cryopreserved human peripheral blood mononuclear cells

Analyzing the cytotoxic functions of effector cells, such as NK cells against target cancer cells, is thought to be necessary for predicting the clinical efficacy of antibody-dependent cellular cytotoxicity (ADCC) -dependent antibody therapy. The (51)Cr release assay has long been the most widely used method for quantification of ADCC activity. However, the reproducibilities of these release assays are not adequate, and they do not allow evaluation of the lysis susceptibilities of distinct cell types within the target cell population. In this study, we established a novel method for evaluating cytotoxicity, which involves the detection and quantification of dead target cells using flowcytometry. CFSE (carboxyfluorescein succinimidyl ester) was used as a dye to specifically stain and thereby label the target cell population, allowing living and dead cells, as well as both target and effector cells, to be quantitatively distinguished. Furthermore, with our new approach, ADCC activity was more reproducibly, sensitively, and specifically detectable, not only in freshly isolated but also in frozen human peripheral blood mononuclear cells (PBMCs), than with the calcein-AM release assay. This assay, validated herein, is expected to become a standard assay for evaluating ADCC activity which will ultimately contribute the clinical development of ADCC dependent-antibody therapies.

Reduced IRF7 response to rhinovirus unrelated with DNA methylation in peripheral mononuclear cells of adult asthmatics

Background

Human rhinoviruses are the major cause of asthma exacerbation in both children and adults. Recently, impaired antiviral interferon (IFN) response in asthmatics has been indicated as a primary reason of the susceptibility to respiratory virus, but the mechanism of defective IFN production is little understood to date. The expression of IFN regulatory factor 7 (IRF7), a transcriptional factor for virus-induced type I IFN production is known to be regulated epigenetically by DNA methylation.

Objective

We aimed to investigate the expression of IFN-α, IFN-β, and IRF7 in response to rhinovirus infection in the adult asthmatics and evaluate DNA methylation status of IRF7 gene promotor.

Methods

Twenty symptomatic adult asthmatics and 10 healthy subjects were enrolled and peripheral blood was collected from each subject. Peripheral blood mononuclear cells (PBMCs) were isolated, cultured, and ex vivo stimulated with rhinovirus-16. The mRNA expressions of IFN-α, IFN-β, and IRF7 were analyzed using real time quantitative polymerase chain reaction. Genomic DNA was isolated from untreated PBMCs and the methylation status of IRF7 gene promotor was investigated using bisulfite pyrosequencing.

Results

The mean age of asthmatics was 45.4 ± 15.7 years and 40% was male, which were not different with those of control group. Asthmatics showed significantly decreased mRNA expressions (relative expression to beta-actin) of IFN-α and IFN-β compared with normal control. The mRNA expression of IRF7 in the asthmatics was also significantly lower than those in the normal control. No significant difference of DNA methylation was observed between asthmatics and controls in all analyzed positions of IRF7 promotor CpG loci.

Conclusion

The mRNA expression of type I IFN in response to rhinovirus was impaired in the PBMCs of adult asthmatics. The mRNA expression of IRF7, transcriptional factor inducing type I IFN was also reduced, but not caused by altered DNA methylation in the IRF7 gene promotor.

Brain-derived circulating endothelial cells in peripheral blood of newborn infants with seizures: a potential biomarker for cerebrovascular injury

Neonatal seizures have been associated with cerebrovascular endothelial injury and neurological disabilities. In a piglet model, the long-term loss of endothelial regulation of cerebral blood flow coincides with the surge of brain-derived circulating endothelial cells (BCECs) in blood. We hypothesized that BCECs could serve as a noninvasive biomarker of cerebrovascular injury in neonates with seizures. In a prospective pilot feasibility study, we enrolled newborn infants with confirmed diagnoses of perinatal asphyxia and intraventricular hemorrhage (IVH); both are commonly associated with seizures. Infants without clinical evidence of cerebrovascular injuries were representative of the control group. BCECs were detected in the CD45-negative fraction of peripheral blood mononuclear cells by coexpression of CD31 (common endothelial antigen) and GLUT1 (blood-brain barrier antigen) via automated flow cytometry method. In Infants with asphyxia (n = 12) and those with IVH grade III/IV (n = 5), the BCEC levels were 9.9 ± 0.9% and 19.0 ± 2.0%, respectively. These levels were significantly higher than the control group (n = 27), 0.9 ± 0.2%, P < 0.001. BCECs in infants with cerebrovascular insults with documented clinical seizures (n = 10; 16.8 ± 1.3%) were significantly higher than infants with cerebrovascular insults with subclinical or no seizures (n = 7; 9.5 ± 1.2%); P < 0.001. BCEC levels decreased with seizure control. BCECs levels were elevated in infants with seizures caused by severe IVH and perinatal asphyxia. We suggest that monitoring BCEC levels in peripheral blood can potentially offer a biological marker that reflects cerebrovascular insult and recovery. Further studies with a larger number of patients are required to support these findings.

Immune biomarkers predictive of respiratory viral infection in elderly nursing home residents

OBJECTIVE

To determine if immune phenotypes associated with immunosenescence predict risk of respiratory viral infection in elderly nursing home residents.

METHODS

Residents ≥ 65 years from 32 nursing homes in 4 Canadian cities were enrolled in Fall 2009, 2010 and 2011, and followed for one influenza season. Following influenza vaccination, peripheral blood mononuclear cells (PBMCs) were obtained and analysed by flow cytometry for T-regs, CD4+ and CD8+ T-cell subsets (CCR7+CD45RA+, CCR7-CD45RA+ and CD28-CD57+) and CMV-reactive CD4+ and CD8+ T-cells. Nasopharyngeal swabs were obtained and tested for viruses in symptomatic residents. A Cox proportional hazards model adjusted for age, sex and frailty, determined the relationship between immune phenotypes and time to viral infection.

RESULTS

1072 residents were enrolled; median age 86 years and 72% female. 269 swabs were obtained, 87 were positive for virus: influenza (24%), RSV (14%), coronavirus (32%), rhinovirus (17%), human metapneumovirus (9%) and parainfluenza (5%). In multivariable analysis, high T-reg% (HR 0.41, 95% CI 0.20-0.81) and high CMV-reactive CD4+ T-cell% (HR 1.69, 95% CI 1.03-2.78) were predictive of respiratory viral infection.

CONCLUSIONS

In elderly nursing home residents, high CMV-reactive CD4+ T-cells were associated with an increased risk and high T-regs were associated with a reduced risk of respiratory viral infection.

The Center for HIV/AIDS Vaccine Immunology (CHAVI) multi-site quality assurance program for cryopreserved human peripheral blood mononuclear cells

The Center for HIV/AIDS Vaccine Immunology (CHAVI) consortium was established to determine the host and virus factors associated with HIV transmission, infection and containment of virus replication, with the goal of advancing the development of an HIV protective vaccine. Studies to meet this goal required the use of cryopreserved Peripheral Blood Mononuclear Cell (PBMC) specimens, and therefore it was imperative that a quality assurance (QA) oversight program be developed to monitor PBMC samples obtained from study participants at multiple international sites. Nine site-affiliated laboratories in Africa and the USA collected and processed PBMCs, and cryopreserved PBMC were shipped to CHAVI repositories in Africa and the USA for long-term storage. A three-stage program was designed, based on Good Clinical Laboratory Practices (GCLP), to monitor PBMC integrity at each step of this process. The first stage evaluated the integrity of fresh PBMCs for initial viability, overall yield, and processing time at the site-affiliated laboratories (Stage 1); for the second stage, the repositories determined post-thaw viability and cell recovery of cryopreserved PBMC, received from the site-affiliated laboratories (Stage 2); the third stage assessed the long-term specimen storage at each repository (Stage 3). Overall, the CHAVI PBMC QA oversight program results highlight the relative importance of each of these stages to the ultimate goal of preserving specimen integrity from peripheral blood collection to long-term repository storage.

Viable mononuclear cell stability study for implementation in a proficiency testing program: impact of shipment conditions

The impact of shipping temperatures and preservation media used during transport of either peripheral blood mononuclear cells (PBMCs) or Jurkat cells was assessed, in view of implementing of a proficiency testing scheme on mononuclear cell viability. Samples were analyzed before and after shipment at different temperatures (ambient temperature, dry ice, and liquid nitrogen) and in different preservation media (serum with cryoprotectant, commercial cryopreservation solution, and room temperature transport medium). Sample quality was assessed by viability assays (Trypan Blue dye exclusion, flow cytometry, Cell Analysis System cell counting (CASY)), and by ELISpot functional assay. The liquid nitrogen storage and shipment were found to be the most stable conditions to preserve cell viability and functionality. However, we show that alternative high quality shipment conditions for viable cells are dry ice shipment and commercial cryopreservation solution. These were also cost-efficient shipment conditions, satisfying the requirements of a proficiency testing scheme for viable mononuclear cells. Room temperature transport medium dramatically and adversely affected the integrity of mononuclear cells.