Gene expression profiles in peripheral blood as a biomarker in cancer patients receiving peptide vaccination

The evolving role of immune cells in prostate cancer

Prostate cancer is the most commonly diagnosed cancer and the second leading cause of cancer-related death among men in western countries. Androgen deprivation therapy (ADT) is considered the standard therapy for recurrent prostate cancer; however, this therapy may lead to ADT resistance and tumor progression, which seems to be regulated by epithelial-mesenchymal transition (EMT) and/or neuroendocrine differentiation (NED). In addition, recent data suggested the involvement of either adaptive or innate infiltrated immune cells in the initiation, progression, metastasis, and treatment of prostate cancer. In this review, we outlined the characteristics and roles of these immune cells in the initiation, progression, metastasis, and treatments of prostate cancer. We also summarized the current therapeutic strategies in targeting immune cells of the prostate tumor microenvironment.

Development of an optimized method for processing peripheral blood mononuclear cells for 1H-nuclear magnetic resonance-based metabolomic profiling

Human peripheral blood mononuclear cells (PBMCs) are part of the innate and adaptive immune system, and form a critical interface between both systems. Studying the metabolic profile of PBMC could provide valuable information about the response to pathogens, toxins or cancer, the detection of drug toxicity, in drug discovery and cell replacement therapy. The primary purpose of this study was to develop an improved processing method for PBMCs metabolomic profiling with nuclear magnetic resonance (NMR) spectroscopy. To this end, an experimental design was applied to develop an alternative method to process PBMCs at low concentrations. The design included the isolation of PBMCs from the whole blood of four different volunteers, of whom 27 cell samples were processed by two different techniques for quenching and extraction of metabolites: a traditional one using organic solvents and an alternative one employing a high-intensity ultrasound probe, the latter with a variation that includes the use of deproteinizing filters. Finally, all the samples were characterized by 1H-NMR and the metabolomic profiles were compared by the method. As a result, two new methods for PBMCs processing, called Ultrasound Method (UM) and Ultrasound and Ultrafiltration Method (UUM), are described and compared to the Folch Method (FM), which is the standard protocol for extracting metabolites from cell samples. We found that UM and UUM were superior to FM in terms of sensitivity, processing time, spectrum quality, amount of identifiable, quantifiable metabolites and reproducibility.

Identification of biomarkers for personalized peptide vaccination in 2,588 cancer patients

Peptide-based cancer vaccines have failed to provide sufficient clinical benefits in order to be approved in clinical trials since the 1990s. To understand the mechanisms underlying this failure, the present study investigated biomarkers associated with the lower overall survival (OS) among 2,588 patients receiving personalized peptide vaccination (PPV). Survival data were obtained from a database of 2,588 cancer patients including 399 patients with lung, 354 with prostate and 344 with colon cancer. They entered into phase II clinical trials of PPV in which 2 to 4 of 31 warehouse peptides were selected for vaccination on an individual patient basis based on human leukocyte antigen (HLA) class IA-types and pre-existing peptide-specific IgG levels. Higher pre-vaccination neutrophil, monocyte and platelet counts, and lower pre-vaccination lymphocyte and red blood cell counts were inversely associated with OS, with higher sensitivities in the proportions of neutrophils and lymphocytes, respectively. The most potent unfavorable and favorable factors for OS were the median percentage of neutrophils (>64.8%) or percentage of lymphocytes (>25.1%) with correlation coefficients (R²) of 0.98 and 0.92, respectively. Higher pre-vaccination levels of c-reactive protein and other inflammatory soluble factors were inversely associated with OS. Pre-vaccination peptide-specific immunity levels had no effect on OS, although lower immune boosting levels were inversely associated with OS. None of the 31 peptides was inversely associated with OS, although a few peptides were positively associated with it. On the whole, the findings of the present study suggested that pre-vaccination inflammatory signatures, but not those of post-vaccination immune induction, were associated with lower clinical benefits of PPV.

Peripheral immune-based biomarkers in cancer immunotherapy: can we realize their predictive potential?

The immunologic landscape of the host and tumor play key roles in determining how patients will benefit from immunotherapy, and a better understanding of these factors could help inform how well a tumor responds to treatment. Recent advances in immunotherapy and in our understanding of the immune system have revolutionized the treatment landscape for many advanced cancers. Notably, the use of immune checkpoint inhibitors has demonstrated durable responses in various malignancies. However, the response to such treatments is variable and currently unpredictable, the availability of predictive biomarkers is limited, and a substantial proportion of patients do not respond to immune checkpoint therapy. Identification and investigation of potential biomarkers that may predict sensitivity to immunotherapy is an area of active research. It is envisaged that a deeper understanding of immunity will aid in harnessing the full potential of immunotherapy, and allow appropriate patients to receive the most appropriate treatments. In addition to the identification of new biomarkers, the platforms and assays required to accurately and reproducibly measure biomarkers play a key role in ensuring consistency of measurement both within and between patients. In this review we discuss the current knowledge in the area of peripheral immune-based biomarkers, drawing information from the results of recent clinical studies of a number of different immunotherapy modalities in the treatment of cancer, including checkpoint inhibitors, bispecific antibodies, chimeric antigen receptor T cells, and anti-cancer vaccines. We also discuss the various technologies and approaches used in detecting and measuring circulatory biomarkers and the ongoing need for harmonization.

In vitro marker gene expression analyses in human peripheral blood mononuclear cells: A tool to assess safety of influenza vaccines in humans

Vaccines are inoculated in healthy individuals from children to the elderly, and thus high levels of safety and consistency of vaccine quality in each lot must meet the required specifications by using preclinical and lot release testing. Because vaccines are inoculated into humans, recapitulation of biological reactions in humans should be considered for test methods. We have developed a new method to evaluate the safety of influenza vaccines using biomarker gene expression in mouse and rat models. Some biomarker genes are already known to be expressed in human lymphocytes, macrophages and dendritic cells; therefore, we considered some of these genes might be common biomarkers for human and mice to evaluate influenza vaccine safety. In this study, we used human peripheral blood mononuclear cells (PBMC) as a primary assessment tool to confirm the usefulness of potential marker genes in humans. Analysis of marker gene expression in PBMC revealed biomarker gene expressions were dose-relatedly increased in toxic reference influenza vaccine (RE)-stimulated PBMC. Although some marker genes showed increased expression in hemagglutinin split vaccine-stimulated PBMC, their expression levels were lower than that of RE in PBMC from two different donors. Many marker gene expressions correlated with chemokine production. Marker genes such as IRF7 were associated with other Type 1 interferon (IFN)-associated signals and were highly expressed in the CD304⁺ plasmacytoid dendritic cell (pDC) population. These results suggest PBMC and their marker genes may be useful for vaccine safety evaluation in humans.

Changes in the liver transcriptome of farmed Atlantic salmon (Salmo salar) fed experimental diets based on terrestrial alternatives to fish meal and fish oil

Background

Dependence on marine natural resources threatens the sustainability of Atlantic salmon aquaculture. In the present study, Atlantic salmon fed for 14 weeks with an experimental diet based on animal by-products and vegetable oil (ABP) exhibited reduced growth performance compared with others fed a fish meal/fish oil based experimental diet (MAR) and a plant protein/vegetable oil-based experimental diet (VEG). To characterize the molecular changes underlying the differences in growth performance, we conducted a 44 K microarray study of the liver transcriptome of the three dietary groups.

Results

The microarray experiment identified 122 differentially expressed features (Rank Products, PFP < 10%). Based on their associated Gene Ontology terms, 46 probes were classified as metabolic and growth-relevant genes, 25 as immune-related, and 12 as related to oxidation-reduction processes. The microarray results were validated by qPCR analysis of 29 microarray-identified transcripts. Diets significantly modulated the transcription of genes involved in carbohydrate metabolism (gck and pfkfb4), cell growth and proliferation (sgk2 and htra1), apoptosis (gadd45b), lipid metabolism (fabp3, idi1, sqs), and immunity (igd, mx, ifit5, and mhcI). Hierarchical clustering and linear correlation analyses were performed to find gene expression patterns among the qPCR-analyzed transcripts, and connections between them and muscle and liver lipid composition. Overall, our results indicate that changes in the liver transcriptome and tissue lipid composition were driven by cholesterol synthesis up-regulation by ABP and VEG diets, and the lower carbohydrate intake in the ABP group. Two of the microarray-identified genes (sgk2 and htra1) might be key to explaining glucose metabolism regulation and the dietary-modulation of the immune system in fish. To evaluate the potential of these genes as predictive biomarkers, we subjected the qPCR data to a stepwise discriminant analysis. Three sets of no more than four genes were found to be able to predict, with high accuracy (67–94%), salmon growth and fatty acid composition.

Conclusions

This study provides new findings on the impact of terrestrial animal and plant products on the nutrition and health of farmed Atlantic salmon, and a new method based on gene biomarkers for potentially predicting desired phenotypes, which could help formulate superior feeds for the Atlantic salmon aquaculture industry.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5188-6) contains supplementary material, which is available to authorized users.

Myeloid-derived cells in prostate cancer progression: phenotype and prospective therapies

Prostate cancer is the second most common cause of cancer mortality in men in the United States. As is the case for other tumor types, accumulating evidence suggests an important role for myeloid-derived cells in the promotion and progression of prostate cancer. Here, we briefly describe myeloid-derived cells that interact with tumor cells and what is known about their immune suppressive function. We next discuss new evidence for tumor cell-mediated myeloid infiltration via the PI3K/PTEN/AKT signaling pathway and an alternative mechanism for immune evasion that may be regulated by an endoplasmic reticulum stress response. Finally, we discuss several interventions that target myeloid-derived cells to treat prostate cancer.

Infiltrating Myeloid Cells Exert Protumorigenic Actions via Neutrophil Elastase

Tissue infiltration and elevated peripheral circulation of granulocytic myeloid-derived cells is associated with poor outcomes in prostate cancer and other malignancies. Although myeloid-derived cells have the ability to suppress T-cell function, little is known about the direct impact of these innate cells on prostate tumor growth. Here, it is reported that granulocytic myeloid-derived suppressor cells (MDSC) are the predominant tumor-infiltrating cells in prostate cancer xenografts established in athymic nude mice. MDSCs significantly increased in number in the peripheral circulation as a function of xenograft growth and were successfully depleted in vivo by Gr-1 antibody treatment. Importantly, MDSC depletion significantly decreased xenograft growth. We hypothesized that granulocytic MDSCs might exert their protumorigenic actions in part through neutrophil elastase (ELANE), a serine protease released upon granulocyte activation. Indeed, it was determined that NE is expressed by infiltrating immune cells and is enzymatically active in prostate cancer xenografts and in prostate tumors of prostate-specific Pten-null mice. Importantly, treatment with sivelestat, a small-molecule inhibitor specific for NE, significantly decreased xenograft growth, recapitulating the phenotype of Gr-1 MDSC depletion. Mechanistically, NE activated MAPK signaling and induced MAPK-dependent transcription of the proliferative gene cFOS in prostate cancer cells. Functionally, NE stimulated proliferation, migration, and invasion of prostate cancer cells in vitro IHC on human prostate cancer clinical biopsies revealed coexpression of NE and infiltrating CD33⁺ MDSCs.Implications: This report suggests that MDSCs and NE are physiologically important mediators of prostate cancer progression and may serve as potential biomarkers and therapeutic targets. Mol Cancer Res; 15(9); 1138-52. ©2017 AACR.

Syndecan-4 as a biomarker to predict clinical outcome for glioblastoma multiforme treated with WT1 peptide vaccine

AIM

In cancer immunotherapy, biomarkers are important for identification of responsive patients. This study was aimed to find biomarkers that predict clinical outcome of WT1 peptide vaccination.

MATERIALS & METHODS

Candidate genes that were expressed differentially between long- and short-term survivors were identified by cDNA microarray analysis of peripheral blood mononuclear cells that were extracted from 30 glioblastoma patients (discovery set) prior to vaccination and validated by quantitative RT-PCR using discovery set and different 23 patients (validation set).

RESULTS

SDC-4 mRNA expression levels distinguished between the long- and short-term survivors: 1-year survival rates were 64.0 and 18.5% in SDC4-low and -high patients, respectively.

CONCLUSION

SDC-4 is a novel predictive biomarker for the efficacy of WT1 peptide vaccine.

Evaluation of prognostic significance of granulocyte-related factors in cancer patients undergoing personalized peptide vaccination

Since cancer vaccines do not always elicit beneficial effects in treated patients, identification of biomarkers for predicting clinical outcomes would be highly desirable. We previously reported that abnormal granulocytes present in peripheral blood mononuclear cells (PBMC) may contribute to poor prognosis in advanced prostate cancer patients receiving personalized peptide vaccination (PPV). In the current study, we examined whether soluble factors derived from granulocytes, such as matrix metalloproteinase 9 (MMP-9), myeloperoxidase (MPO), and arginase 1 (ARG1), and inhibitory cytokine TGFβ in pre-vaccination plasma were useful for predicting prognosis after PPV in advanced cancer patients. In biliary tract cancer (n=25), multivariate Cox regression analysis demonstrated that patients with higher plasma MMP-9 levels had a significantly worse overall survival (OS) [hazard ratio (HR) = 4.637, 95% confidence interval (CI) = 1.670 - 12.877, P = 0.003], whereas MPO, ARG1, or TGFβ levels were not correlated with OS. Similarly, patients with higher MMP-9 levels showed worse prognosis than those with lower MMP-9 levels in other types of advanced cancers, including non-small cell lung cancer (n=32, P = 0.037 by log-rank test), and pancreatic cancer (n=41, P = 0.042 by log-rank test). Taken together, plasma MMP-9 levels before vaccination might be potentially useful as a biomarker for selecting advanced cancer patients who would benefit from PPV.

Prospect and progress of personalized peptide vaccinations for advanced cancers

INTRODUCTION

The field of cancer immunotherapy has made dramatic progress in the past 20 years, in part due to the identification of numerous tumor-associated antigens (TAAs). We have developed a novel immunotherapeutic approach called the personalized peptide vaccine (PPV), in which a maximum of four human leukocyte antigen (HLA)-matched vaccine peptides are selected based on the pre-existing host immunity before vaccination.

AREAS COVERED

This review describes recent progress in the use of PPV for various types of advanced cancer.

EXPERT OPINION

Although various approaches for therapeutic cancer immunotherapies, including peptide-based vaccines, have been developed and clinically examined, the diverse and heterogeneous characteristics of tumor cells and host immunity seem to limit their therapeutic efficacy. Selection of suitable peptide vaccines for individual patients based on the pre-existing host immunity before vaccination could resolve this limitation and could be a rational approach for developing effective cancer vaccines.

Molecular profiling of peripheral blood is associated with circulating tumor cells content and poor survival in metastatic castration-resistant prostate cancer

The enumeration of circulating tumor cells (CTCs) in peripheral blood correlates with clinical outcome in castration-resistant prostate cancer (CRPC). We analyzed the molecular profiling of peripheral blood from 43 metastatic CRPC patients with known CTC content in order to identify genes that may be related to prostate cancer progression. Global gene expression analysis identified the differential expression of 282 genes between samples with ≥5 CTCs vs <5 CTCs, 58.6% of which were previously described as over-expressed in prostate cancer (18.9% in primary tumors and 56.1% in metastasis). Those genes were involved in survival functions such as metabolism, signal transduction, gene expression, cell growth, death, and movement. The expression of selected genes was evaluated by quantitative RT-PCR. This analysis revealed a two-gene model (SELENBP1 and MMP9) with a high significant prognostic ability (HR 6; 95% CI 2.61 - 13.79; P<0.0001). The combination of the two-gene signature plus the CTCs count showed a higher prognostic ability than CTCs enumeration or gene expression alone (P<0.05). This study shows a gene expression profile in PBMNC associated with CTCs count and clinical outcome in metastatic CRPC, describing genes and pathways potentially associated with CRPC progression.

Analyses of 123 Peripheral Human Immune Cell Subsets: Defining Differences with Age and between Healthy Donors and Cancer Patients Not Detected in Analysis of Standard Immune Cell Types

Recent advances in human immunology have led to the identification of novel immune cell subsets and the biological function of many of these subsets has now been identified. The recent US Food and Drug Administration approval of several immunotherapeutics for the treatment of a variety of cancer types and the results of ongoing immunotherapy clinical studies requires a more thorough interrogation of the immune system. We report here the use of flow cytometry-based analyses to identify 123 immune cell subsets of peripheral blood mononuclear cells. The use of these panels defines multiple differences in younger (< 40 years) vs. older (≥ 40 years) individuals and between aged-matched apparently healthy individuals and metastatic cancer patients, aspects not seen in the analysis of the following standard immune cell types: CD8, CD4, natural killer, natural killer-T, regulatory T, myeloid derived suppressor cells, conventional dendritic cells (DCs), plasmacytoid DCs and B cells. The use of these panels identifying 123 immune cell subsets may aid in the identification of patients who may benefit from immunotherapy, either prior to therapy or early in the immunotherapeutic regimen, for the treatment of cancer or other chronic or infectious diseases.

Haptoglobin promoter polymorphism rs5472 as a prognostic biomarker for peptide vaccine efficacy in castration-resistant prostate cancer patients

Personalized peptide vaccination (PPV) is an attractive approach to cancer immunotherapy with strong immune-boosting effects conferring significant clinical benefit. However, as with most therapeutic agents, there is a difference in clinical efficacy among patients receiving PPV. Therefore, a useful biomarker is urgently needed for prognosticating clinical outcomes to preselect patients who would benefit the most from PPV. In this retrospective study, to detect a molecular prognosticator of clinical outcomes for PPV, we analyzed whole-genome gene expression profiles of peripheral blood mononuclear cells (PBMCs) in castration-resistant prostate cancer (CRPC) patients before administration of PPV. Cox regression analysis revealed that mRNA expression of myeloperoxidase, haptoglobin, and neutrophil elastase was significantly associated with overall survival (OS) among vaccinated CRPC patients (adjusted P < 0.01). By promoter sequence analysis of these three genes, we found that rs5472 of haptoglobin (HP), an acute-phase plasma glycoprotein, was strongly correlated to OS of vaccinated CRPC patients (P = 0.0047, hazard ratio 0.47; 95 % confidence interval 0.28-0.80). Furthermore, both HP mRNA expression in PBMCs and protein level in plasma of CRPC patients before administration of PPV exhibited rs5472 dependence (P < 0.001 for mRNA expression and P < 0.05 for protein level). Our findings suggest that rs5472 may play an important role in the immune response to PPV via regulation of HP. Thus, we concluded that rs5472 is a potential prognostic biomarker for PPV.

Immune cell subsets and their gene expression profiles from human PBMC isolated by Vacutainer Cell Preparation Tube (CPT™) and standard density gradient

Background

High quality genetic material is an essential pre-requisite when analyzing gene expression using microarray technology. Peripheral blood mononuclear cells (PBMC) are frequently used for genomic analyses, but several factors can affect the integrity of nucleic acids prior to their extraction, including the methods of PBMC collection and isolation. Due to the lack of the relevant data published, we compared the Ficoll-Paque density gradient centrifugation and BD Vacutainer cell preparation tube (CPT) protocols to determine if either method offered a distinct advantage in preparation of PBMC-derived immune cell subsets for their use in gene expression analysis. We evaluated the yield and purity of immune cell subpopulations isolated from PBMC derived by both methods, the quantity and quality of extracted nucleic acids, and compared gene expression in PBMC and individual immune cell types from Ficoll and CPT isolation protocols using Affymetrix microarrays.

Results

The mean yield and viability of fresh PBMC acquired by the CPT method (1.16 × 10⁶ cells/ml, 93.3 %) were compatible to those obtained with Ficoll (1.34 × 10⁶ cells/ml, 97.2 %). No differences in the mean purity, recovery, and viability of CD19+ (B cells), CD8+ (cytotoxic T cells), CD4+ (helper T cell) and CD14+ (monocytes) positively selected from CPT- or Ficoll-isolated PBMC were found. Similar quantities of high quality RNA and DNA were extracted from PBMC and immune cells obtained by both methods. Finally, the PBMC isolation methods tested did not impact subsequent recovery and purity of individual immune cell subsets and, importantly, their gene expression profiles.

Conclusions

Our findings demonstrate that the CPT and Ficoll PBMC isolation protocols do not differ in their ability to purify high quality immune cell subpopulations. Since there was no difference in the gene expression profiles between immune cells obtained by these two methods, the Ficoll isolation can be substituted by the CPT protocol without conceding phenotypic changes of immune cells and compromising the gene expression studies. Given that the CPT protocol is less elaborate, minimizes cells’ handling and processing time, this method offers a significant operating advantage, especially in large-scale clinical studies aiming at dissecting gene expression in PBMC and PBMC-derived immune cell subpopulations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-015-0113-0) contains supplementary material, which is available to authorized users.

Phase I trial of a cancer vaccine consisting of 20 mixed peptides in patients with castration-resistant prostate cancer: dose-related immune boosting and suppression

The heterogeneity expression of tumor-associated antigens (TAA) and variability of human T cell repertoire suggest that effective cancer vaccine requires induction of a wide breadth of cytotoxic T lymphocyte (CTL) specificities. This can be achieved with vaccines targeting multiple TAA. We evaluated the safety and immune dynamics of a cancer vaccine consisting of 20 mixed peptides (KRM-20) designed to induce CTLs against 12 different TAA in patients with castration-resistant prostate cancer (CRPC). Patients received each of three different randomly assigned doses of KRM-20 (6, 20, or 60 mg) once a week for 6 weeks. KRM-20 was applicable for patients with positive human leukocyte antigen (HLA) A2, A3, A11, A24, A26, A31 or A33 alleles, which cover the majority of the global population. To evaluate the minimum immunological effective dose (MIED), peptide-specific CTL and immunoglobulin G (IgG) responses, and immune suppressive subsets were evaluated during the vaccination. Total of 17 patients was enrolled. No serious adverse drug reactions were encountered. The MIED of KRM-20 in CTL or IgG response calculated by logistic regression model was set as 16 or 1.6 mg, respectively. The frequency of immune suppressive subsets was fewer in the 20 mg cohort than that in 6 or 60 mg cohort. Clinical responses determined by prostate-specific antigen levels were two partial responses (from the 20 mg cohort), five no changes and ten progressive diseases. Twenty milligrams of KRM-20 could be recommended for further studies because of the safety and ability to augment CTL activity.

Personalized peptide vaccination for advanced colorectal cancer

We have developed a novel approach in cancer immunotherapy, the personalized peptide vaccination (PPV), in which human leukocyte antigen (HLA)-matched peptides are selected on the basis of preexisting host immunity before vaccination. Recently, we demonstrated the feasibility of PPV in previously treated patients with advanced colorectal cancer, thus warranting further clinical development of this approach.

Feasibility study of personalized peptide vaccination for recurrent ovarian cancer patients

CONTEXT

To develop a personalized peptide vaccine (PPV) for recurrent ovarian cancer patients and evaluate its efficacy from the point of view of overall survival (OS), Phase II study of PPV was performed.

PATIENTS AND METHODS

Forty-two patients, 17 with platinum-sensitive and 25 with platinum-resistant recurrent ovarian cancer, were enrolled in this study and received a maximum of four peptides based on HLA-A types and IgG responses to the peptides in pre-vaccination plasma.

RESULTS

Expression of 13 of the 15 parental tumor-associated antigens encoding the vaccine peptides, with the two prostate-related antigens being the exceptions, was confirmed in the ovarian cancer tissues. No vaccine-related systemic severe adverse events were observed in any patients. Boosting of cytotoxic T lymphocytes or IgG responses specific for the peptides used for vaccination was observed in 18 or 13 of 42 cases at 6th vaccination, and 19 or 29 of 30 cases at 12th vaccination, respectively. The median survival time (MST) values of the platinum-sensitive- and platinum-resistant recurrent cases were 39.3 and 16.2 months, respectively. The MST of PPV monotherapy or PPV in combination with any chemotherapy during the 1st to 12th vaccination of platinum-sensitive cases was 39.3 or 32.2 months, and that of platinum-resistant cases was 16.8 or 16.1 months, respectively. Importantly, lymphocyte frequency and epitope spreading were significantly prognostic of OS.

DISCUSSION AND CONCLUSION

Because of the safety and possible prolongation of OS, a clinical trial of PPV without chemotherapy during the 1st to 12th vaccination in recurrent ovarian cancer patients is merited.

Characterization of the ovine complement 4 binding protein-beta (C4BPB) chain as a serum biomarker for enhanced diagnosis of sheep scab

Sheep scab, caused by the highly contagious mite Psoroptes ovis, is endemic in a number of sheep-producing countries worldwide, and is a major animal welfare and economic concern. Recent developments in the diagnosis of sheep scab include a highly sensitive and specific serum antibody-based assay which can be used to indicate exposure to the parasite but not necessarily current disease status. Here, a transcriptomic and bioinformatics analysis of the circulating leukocytes of sheep with active P. ovis infestation indicated that the transcription levels of complement 4 binding protein beta (C4BPB) increased by 12 fold from pre-infestation to 6 weeks post-infestation. Semi-quantitative studies confirmed increased serum C4BPB protein levels in sheep infested with P. ovis. To quantify this serum protein response and characterize ovine C4BPB as a biomarker for active P. ovis infestation, the ovine C4BPB gene was sequenced, a recombinant protein expressed, antibodies against this protein were raised in rabbits and a sandwich ELISA developed. The results from this assay indicated that serum C4BPB protein levels increased 4-fold from pre-infestation to 6 weeks post-infestation, which demonstrated the potential of the assay to quantify C4BPB in sheep sera and indicated the potential of C4BPB as a biomarker of current disease status in sheep post-infestation and post-treatment.

Immunotherapy for castration-resistant prostate cancer

The improved survival with sipuleucel-T, an autologous antigen-presenting cell-based agent, for the treatment of patients with metastatic asymptomatic and minimally symptomatic castration-resistant prostate cancer supports immunotherapy as a valid approach. Also, multiple novel immunotherapeutic approaches are undergoing vigorous investigation. T-lymphocyte checkpoint blockade and poxvirus-based prime-boost approaches are in phase III evaluation. Other immunotherapeutic platforms undergoing early investigation include radioimmunoconjugates and adenovirus-based, DNA-based, and Listeria-based approaches. The development of predictive markers for immune response that translate into improved long-term outcomes is important. This article reviews the emerging data and the unique strengths and weaknesses of these approaches.

Accurate measurement of peripheral blood mononuclear cell concentration using image cytometry to eliminate RBC-induced counting error

Peripheral blood mononuclear cells (PBMCs) have been widely researched in the fields of immunology, infectious disease, oncology, transplantation, hematological malignancy, and vaccine development. Specifically, in immunology research, PBMCs have been utilized to monitor concentration, viability, proliferation, and cytokine production from immune cells, which are critical for both clinical trials and biomedical research. The viability and concentration of isolated PBMCs are traditionally measured by manual counting with trypan blue (TB) using a hemacytometer. One of the common issues of PBMC isolation is red blood cell (RBC) contamination. The RBC contamination can be dependent on the donor sample and/or technical skill level of the operator. RBC contamination in a PBMC sample can introduce error to the measured concentration, which can pass down to future experimental assays performed on these cells. To resolve this issue, RBC lysing protocol can be used to eliminate potential error caused by RBC contamination. In the recent years, a rapid fluorescence-based image cytometry system has been utilized for bright-field and fluorescence imaging analysis of cellular characteristics (Nexcelom Bioscience LLC, Lawrence, MA). The Cellometer image cytometry system has demonstrated the capability of automated concentration and viability detection in disposable counting chambers of unpurified mouse splenocytes and PBMCs stained with acridine orange (AO) and propidium iodide (PI) under fluorescence detection. In this work, we demonstrate the ability of Cellometer image cytometry system to accurately measure PBMC concentration, despite RBC contamination, by comparison of five different total PBMC counting methods: (1) manual counting of trypan blue-stained PBMCs in hemacytometer, (2) manual counting of PBMCs in bright-field images, (3) manual counting of acetic acid lysing of RBCs with TB-stained PBMCs, (4) automated counting of acetic acid lysing of RBCs with PI-stained PBMCs, and (5) AO/PI dual staining method. The results show comparable total PBMC counting among all five methods, which validate the AO/PI staining method for PBMC measurement in the image cytometry method.

Personalized peptide vaccination: a novel immunotherapeutic approach for advanced cancer

Since both tumor cells and immune cell repertoires are diverse and heterogeneous, immune responses against tumor-associated antigens might be substantially different among individual patients. Personalized selection of right peptides for individuals could thus be an appropriate strategy for cancer vaccines. We have developed a novel immunotherapeutic approach, personalized peptide vaccination (PPV), in which HLA-matched peptides are selected and administered, based on the pre-existing host immunity before vaccination. Recent clinical trials of PPV have demonstrated a feasibility of this new therapeutic approach in various types of advanced cancers. For example, a randomized phase II trial for patients with castration resistant prostate cancer showed a possible clinical benefit in the PPV group. In the patients undergoing PPV, lymphocyte counts, increased IgG responses to the vaccine peptides, and inflammatory factors in pre-vaccination peripheral blood might be potential biomarkers for prognosis. Further randomized phase III trials would be recommended to prove clinical benefits of PPV.

Evaluation of antigen specific recognition and cell mediated cytotoxicity by a modified lysispot assay in a rat colon carcinoma model

Background

Antigen-specific CD8+ cytotoxic T lymphocytes represent potent effector cells of the adaptive immune response against viruses as well as tumours. Therefore assays capable at exploring the generation and function of cytotoxic T lymphocytes represent an important objective for both clinical and experimental settings.

Methods

Here we show a simple and reproducible assay for the evaluation of antigen-specific CD8+ cytotoxic T lymphocytes based on a LysiSpot technique for the simultaneous determination of antigen-specific IFN-γ production and assessment of tumor cytolysis. The assay was developed within an experimental model of colorectal carcinoma, induced by the colorectal tumor cell line DHD-K12 that induces tumors in BDIX rats and, in turn, elicits a tumor- specific immune response.

Results

Using DHD-K12 cells transfected to express Escherichia coli β-galactosidase as target cells, and by the fine setting of spot colours detection, we have developed an in vitro assay that allows the recognition of cytotoxic T lymphocytes induced in BDIX rats as well as the assessment of anti-tumour cytotoxicity. The method highlighted that in the present experimental model the tumour antigen-specific immune response was bound to killing target cells in the proportion of 55%, while 45% of activated cells were not cytotoxic but released IFN-γ. Moreover in this model by an ELISPOT assay we demonstrated the specific recognition of a nonapeptide epitope called CSH-275 constitutionally express in DHD-K12 cells.

Conclusions

The assay proved to be highly sensitive and specific, detecting even low frequencies of cytotoxic/activated cells and providing the evaluation of cytokine-expressing T cells as well as the extent of cytotoxicity against the target cells as independent functions. This assay may represent an important tool to be adopted in experimental settings including the development of vaccines or immune therapeutic strategies