Lymphocyte immunophenotyping by flow cytometry in normal adults. Comparison of fresh whole blood lysis technique, Ficoll-Paque separation and cryopreservation

Dose effect of corticosteroids on peripheral lymphocyte profiles in patients with systemic lupus erythematosus

OBJECTIVE

To investigate the dose effect of methylprednisolone (MP) on peripheral lymphocyte profiles in patients with systemic lupus erythematosus (SLE). This study investigated the impact of varied MP doses on peripheral lymphocyte subtypes in SLE patients.

METHODS

We conducted a prospective study involving 51 SLE patients, categorized into four groups (40 mg/day, 80 mg/day, 500 mg/day, and 1000 mg/day) based on the administered MP dosage during hospitalization. We analyzed the lymphocyte count and proportion in peripheral blood, along with their subpopulations, before and after MP treatment using the paired Mann-Whitney U test.

RESULTS

Treatment with a clinically rational dose of MP (40 mg/day or 80 mg/day) resulted in increased lymphocyte counts, encompassing total lymphocytes, T cells, CD4 + T cells, regulatory T cells (Treg), and effector T cells (Teff) in the short term. Conversely, the counts of these cells decreased with pulse MP (500 mg/day or 1000 mg/day). The percentage of Treg cells and the Treg/Teff ratio increased following 40 mg or 80 mg MP/day treatment, whereas they decreased after pulse therapy. A gradual augmentation in the count and percentage of Treg cells was observed during continuous administration of 40 mg or 80 mg MP/day for 1 week, while in patients receiving pulse therapy, Treg cells tended to decrease during the therapy but rapidly recovered upon MP reduction.

CONCLUSION

Lower doses of MP in the short term increased Treg cells, inhibiting systemic inflammation in SLE. High-dose pulse therapy exhibited a suppressive effect on Tregs. Key Points • Different dosages of methylprednisolone have variable effects on peripheral lymphocyte subsets. • Methylprednisolone pulse therapy leads to a rapid decrease in Treg cells. • Clinically rational methylprednisolone treatment leads to an increase in Treg cells.

Flow Cytometric Immunophenotyping: Minimal Differences in Fresh and Cryopreserved Peripheral Blood Mononuclear Cells versus Whole Blood

Background/Objectives: Flow cytometry is a convenient tool in immunophenotyping for monitoring the status of immunological conditions and diseases. The aim of this study was to investigate the effect of isolation and cryopreservation by flow cytometric analysis on subpopulations of CD4+ T helper (Th), T regulatory (Treg), CD8+ T cytotoxic (Tc), CD56+ NK, CD19+ B and monocytes. Freshly isolated and cryopreserved peripheral blood mononuclear cells (PBMCs) were compared to fresh whole blood. Methods: Peripheral blood was collected from healthy donors and prepared for flow cytometric analysis using the same panels of antibodies throughout the study. Results: Comparisons between fresh (F)- and cryopreserved (C)-PBMCs showed no major differences in percentages of CD4+, Th1, Th2 and CD4+CD25+CD127low Treg cells. No differences in percentage of CD8+ or subpopulations of naive/stem, central or effector memory cells were observed between F- and C-PBMCs. The percentage of CD56+ NK cells, CD19+ B cells or classical and nonclassical monocytes did not differ between F-and C-PBMCs either. On the contrary, whole blood had lower percentages of Th and NK cells but higher percentages of Th1, Th17, Th1Th17, Tregs, Tc and B cells compared to C-PBMCs, while it had a higher proportion of Tc compared to F-PBMCs. Conclusions: Flow cytometric immunophenotyping minimally differs between freshly isolated and cryopreserved PBMCs. This implies the possibility of cryostorage of cohorts for later analysis. Importantly, care must be taken when comparing results from whole blood with isolated and cryopreserved PBMCs. Collectively, these results can contribute to the standardization of flow cytometric protocols in both clinical and research settings.

Reprogramming of T cell-derived small extracellular vesicles using IL2 surface engineering induces potent anti-cancer effects through miRNA delivery

T cell-derived small extracellular vesicles (sEVs) exhibit anti-cancer effects. However, their anti-cancer potential should be reinforced to enhance clinical applicability. Herein, we generated interleukin-2-tethered sEVs (IL2-sEVs) from engineered Jurkat T cells expressing IL2 at the plasma membrane via a flexible linker to induce an autocrine effect. IL2-sEVs increased the anti-cancer ability of CD8+ T cells without affecting regulatory T (Treg ) cells and down-regulated cellular and exosomal PD-L1 expression in melanoma cells, causing their increased sensitivity to CD8+ T cell-mediated cytotoxicity. Its effect on CD8+ T and melanoma cells was mediated by several IL2-sEV-resident microRNAs (miRNAs), whose expressions were upregulated by the autocrine effects of IL2. Among the miRNAs, miR-181a-3p and miR-223-3p notably reduced the PD-L1 protein levels in melanoma cells. Interestingly, miR-181a-3p increased the activity of CD8+ T cells while suppressing Treg cell activity. IL2-sEVs inhibited tumour progression in melanoma-bearing immunocompetent mice, but not in immunodeficient mice. The combination of IL2-sEVs and existing anti-cancer drugs significantly improved anti-cancer efficacy by decreasing PD-L1 expression in vivo. Thus, IL2-sEVs are potential cancer immunotherapeutic agents that regulate both immune and cancer cells by reprogramming miRNA levels.

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.

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.

Skin-homing T-cell responses associated with Demodex infestation and rosacea

AIMS

Our aim was to investigate the skin-homing T-cell immune responses triggered in patients with Demodex infestation and/or rosacea.

METHODS

Collected whole blood samples were divided into four groups: control subjects; nonrosacea patients with Demodex infestation (Demodex group); papulopustular rosacea (PPR) patients without Demodex infestation (Rosacea group); and PPR patients with Demodex infestation (Rosacea/Demodex group). Following ex vivo activation, skin-homing CLA+CD4+ T-cell subset levels were monitored by flow cytometry.

RESULTS

When compared with control subjects, among skin-homing CD4+ T-cell subsets analysed, Demodex patients had higher T_H 9 and T_reg cell levels; Rosacea subjects displayed elevated T_H 1 cell levels; and Rosacea/Demodex patients exhibited increased frequencies of T_H 9 and T_H 22 cells. In contrast to Rosacea subjects, Rosacea/Demodex group members displayed higher T_H 2 cell levels; and when compared with Demodex groups, they had higher T_H 1 and T_H 2 but lower T_reg cell levels. Demodex group members also exhibited higher T_reg but lower T_H 1 and T_H 22 levels than Rosacea/Demodex group subjects.

CONCLUSIONS

The skin-homing T-cell responses associated with Demodex infestation and rosacea formation seem to influence each other. The present as well as future studies could contribute to the development of effective treatment strategies for demodicosis and rosacea.

Multiparametric analysis of CD8+ T cell compartment phenotype in chronic lymphocytic leukemia reveals a signature associated with progression toward therapy

CD8⁺ T cells are frontline defenders against cancer and primary targets of current immunotherapies. In CLL, specific functional alterations have been described in circulating CD8⁺ T cells, yet a global view of the CD8⁺ T cell compartment phenotype and of its real impact on disease progression is presently elusive. We developed a multidimensional statistical analysis of CD8⁺ T cell phenotypic marker expression based on whole blood multi-color flow-cytometry. The analysis comprises both unsupervised statistics (hClust and PCA) and supervised classification methods (Random forest, Adaboost algorithm, Decision tree learning and logistic regression) and allows to cluster patients by comparing multiple phenotypic markers expressed by CD8⁺ T cells.

Our results reveal a global CD8⁺ T cell phenotypic signature in CLL patients that is significantly modified when compared to healthy donors. We also uncover a CD8⁺ T cell signature characteristic of patients evolving toward therapy within 6 months after phenotyping. The unbiased, not predetermined and multimodal approach highlights a prominent role of the memory compartment in the prognostic signature. The analysis also reveals that imbalance of the central/effector memory compartment in CD8⁺ T cells can occur irrespectively of the elapsed time after diagnosis.

Taken together our results indicate that, in CLL patients, CD8⁺ T cell phenotype is imprinted by disease clinical progression and reveal that CD8⁺ T cell memory compartment alteration is not only a hallmark of CLL disease but also a signature of disease evolution toward the need for therapy.

Aberrant determination of phenotypic markers in chronic lymphocytic leukemia (CLL) lymphocytes after cryopreservation

The cryopreservation of peripheral blood mononuclear cells (PBMCs) is a routine research laboratory process, enabling long-term storage of primary patient blood samples. Retrospective analysis of these samples has the potential to identify markers that may be associated with prognosis and response to treatment. To draw valid biological conclusions from this type of analysis, it is essential to ensure that any observed changes are directly related to the pathology of the disease rather than the preservation process itself. Therefore, we have investigated 15 cell surface markers that are relevant to chronic lymphocytic leukemia (CLL) on matched fresh and thawed samples to determine the effect of cryopreservation on their detection. We found that the number of CLL cells positive for the markers CD22, CD40, CD49d, CD54, CD69, and CXCR3 was decreased significantly after cryopreservation. In addition, the mean fluorescence intensity of 10 of the 15 markers changed significantly after cryopreservation. These findings demonstrate that care must be taken when interpreting this type of analysis on thawed samples.

The Trojan horse - neuroinflammatory impact of T cells in neurodegenerative diseases

Neuronal degeneration is a common mechanism of many neurological diseases including Parkinson’s disease (PD), Alzheimer’s disease (AD), and Multiple Sclerosis (MS). While AD and PD are classical neurodegenerative diseases, the primary pathology in MS is driven by autoimmune inflammation, attacking oligodendrocytes and thereby inducing neurodegeneration. In AD and PD, immune cells are also considered to play an important role in the disease progression. While the role of local central nervous system (CNS) innate immune cells is well described, a potential influence of adaptive immune cells in PD and AD is not yet fully understood.

Here, we aim to summarize findings concerning adaptive immune cells in PD pathogenesis and compare them to AD and MS. In the first part, we focus on disease-specific alterations of lymphocytes in the circulating blood. Subsequently, we describe what is known about CNS-infiltrated lymphocytes and mechanisms of their infiltration. Finally, we summarize published data and try to understand the mechanisms of how lymphocytes contribute to neurodegeneration in PD, AD, and MS.

Lymphocytes are critically involved in the pathogenesis of MS, and clarifying the role of lymphocytes in PD and AD pathogenesis might lead to an identification of a common signature of lymphocytes in neurodegeneration and thus pave the road towards novel treatment options.

Suitability of small diagnostic peripheral-blood samples for cell-therapy studies

BACKGROUND AIMS

Primary hematopoietic stem and progenitor cells (HSPCs) are key components of cell-based therapies for blood disorders and are thus the authentic substrate for related research. We propose that ubiquitous small-volume diagnostic samples represent a readily available and as yet untapped resource of primary patient-derived cells for cell- and gene-therapy studies.

METHODS

In the present study we compare isolation and storage methods for HSPCs from normal and thalassemic small-volume blood samples, considering genotype, density-gradient versus lysis-based cell isolation and cryostorage media with different serum contents. Downstream analyses include viability, recovery, differentiation in semi-solid media and performance in liquid cultures and viral transductions.

RESULTS

We demonstrate that HSPCs isolated either by ammonium-chloride potassium (ACK)-based lysis or by gradient isolation are suitable for functional analyses in clonogenic assays, high-level HSPC expansion and efficient lentiviral transduction. For cryostorage of cells, gradient isolation is superior to ACK lysis, and cryostorage in freezing media containing 50% fetal bovine serum demonstrated good results across all tested criteria. For assays on freshly isolated cells, ACK lysis performed similar to, and for thalassemic samples better than, gradient isolation, at a fraction of the cost and hands-on time. All isolation and storage methods show considerable variation within sample groups, but this is particularly acute for density gradient isolation of thalassemic samples.

DISCUSSION

This study demonstrates the suitability of small-volume blood samples for storage and preclinical studies, opening up the research field of HSPC and gene therapy to any blood diagnostic laboratory with corresponding bioethics approval for experimental use of surplus material.

Comparative phenotypical analysis of B cells in fresh and cryopreserved mononuclear cells from blood and tissue of rhesus macaques

Cryopreservation of peripheral blood mononuclear cells (PBMCs) is common for large clinical trials for which phenotypical characterization of lymphocytes is retrospectively performed in specialized core laboratories. It is therefore essential to assess the comparability between fresh and frozen samples. No side-by-side comparison of B and plasma cells of rhesus macaques (RM), which serve as useful models for several human diseases has been conducted until now. Hence, we performed an extensive comparative analysis between fresh and thawed mononuclear cells (MNCs) from blood and various tissues of healthy RM to analyze for the possible effects of cryopreservation on phenotype and functionality. Our data demonstrate that -80°C cryopreservation induces profound changes compared to fresh ex vivo-derived material. Percentages of B cells were stable in PBMCs, but were increased in all organs analyzed. The expression of CD27, a marker for differentiation between naïve and memory B cells, was massively reduced in PBMCs and MNC from organs with the most severe changes observed in cells from bone marrow (BM). Additionally, similar low percentages of CD27(+) memory B cells were detected in PBMCs and BM samples stored in liquid nitrogen. Therefore, cryopreservation is not suitable for the phenotypical and functional characterization of B cells. Further optimization of cryoconservation protocols monitoring the surface expression of CD27, which was identified as a marker for the quality of cryopreserved material of RM, will be essential.

Effect of storage conditions on subpopulations of peripheral blood T lymphocytes isolated from naïve cattle and cattle infected with foot-and-mouth disease virus

BACKGROUND

Immunophenotyping of blood lymphocytes by flow cytometry is important in infectious disease research. In animal experiments and other longitudinal studies, the processing, prompt staining, and analysis of fresh samples is a logistical challenge and daily assay variation can confound data interpretation.

OBJECTIVE

This study examined the feasibility of cryopreservation and deferred analysis of bovine peripheral blood T lymphocytes from normal or infected animals.

METHODS

Peripheral blood mononuclear cells were collected from 4 naïve Holstein steers and 4 steers infected with foot-and-mouth-disease virus serotype Asia1. Identical aliquots were labeled and analyzed immediately, labeled for deferred analysis, or stored at -70°C or over liquid nitrogen for up to 3 weeks before labeling.

RESULTS

Freezing of unlabeled cells induced statistically significant changes in phenotypic recognition. In infected animals, the γδ T-cell population increased by 28% and CD8(+) αβT cells by 32%, while total CD3(+) cells decreased by 16%, and CD4(+) αβT cells decreased by 12%. Subsequent storage of frozen cells for the duration of the study, however, had no significant effect. There was less than 20% relative change in subpopulation sizes, and storage at -70°C or over liquid nitrogen was equivalent.

CONCLUSIONS

Depending on the objectives and practical limitations of a study, deferred labeling of peripheral blood lymphocytes can be a viable option. Although frozen storage of lymphocytes can introduce some artifactual distortion of relative cell populations, frozen cells can be maintained in storage until all samples in a longitudinal study can be analyzed in batch under standardized conditions and without introducing further bias.

Density gradient centrifugation compromises bone marrow mononuclear cell yield

Bone marrow mononuclear cells (BMNCs) are widely used in regenerative medicine, but recent data suggests that the isolation of BMNCs by commonly used Ficoll-Paque density gradient centrifugation (DGC) causes significant cell loss and influences graft function. The objective of this study was to determine in an animal study whether and how Ficoll-Paque DGC affects the yield and composition of BMNCs compared to alternative isolation methods such as adjusted Percoll DGC or immunomagnetic separation of polymorphonuclear cells (PMNs). Each isolation procedure was confounded by a significant loss of BMNCs that was maximal after Ficoll-Paque DGC, moderate after adjusted Percoll DGC and least after immunomagnetic PMN depletion (25.6±5.8%, 51.5±2.3 and 72.3±6.7% recovery of total BMNCs in lysed bone marrow). Interestingly, proportions of BMNC subpopulations resembled those of lysed bone marrow indicating symmetric BMNC loss independent from the isolation protocol. Hematopoietic stem cell (HSC) content, determined by colony-forming units for granulocytes-macrophages (CFU-GM), was significantly reduced after Ficoll-Paque DGC compared to Percoll DGC and immunomagnetic PMN depletion. Finally, in a proof-of-concept study, we successfully applied the protocol for BMNC isolation by immunodepletion to fresh human bone marrow aspirates. Our findings indicate that the common method to isolate BMNCs in both preclinical and clinical research can be considerably improved by replacing Ficoll-Paque DGC with adapted Percoll DGC, or particularly by immunodepletion of PMNs.

A model for harmonizing flow cytometry in clinical trials

Complexities in sample handling, instrument setup and data analysis are barriers to the effective use of flow cytometry to monitor immunological parameters in clinical trials. The novel use of a central laboratory may help mitigate these issues.

Quality monitoring of HIV-1-infected and uninfected peripheral blood mononuclear cell samples in a resource-limited setting

Human immunodeficiency virus type 1 (HIV-1) vaccine and natural history studies are critically dependent on the ability to isolate, cryopreserve, and thaw peripheral blood mononuclear cell (PBMC) samples with a high level of quality and reproducibility. Here we characterize the yield, viability, phenotype, and function of PBMC from HIV-1-infected and uninfected Ugandans and describe measures to ascertain reproducibility and sample quality at the sites that perform cryopreservation. We have developed a comprehensive internal quality control program to monitor processing, including components of method validation. Quality indicators for real-time performance assessment included the time from venipuncture to cryopreservation, time for PBMC processing, yield of PBMC from whole blood, and viability of the PBMC before cryopreservation. Immune phenotype analysis indicated lowered B-cell frequencies following processing and cryopreservation for both HIV-1-infected and uninfected subjects (P < 0.007), but all other major lymphocyte subsets were unchanged. Long-term cryopreservation did not impact function, as unstimulated specimens exhibited low background and all specimens responded to staphylococcal enterotoxin B (SEB) by gamma interferon and interleukin-2 production, as measured by intracellular cytokine staining. Samples stored for more than 3 years did not decay with regard to yield or viability, regardless of HIV-1 infection status. These results demonstrate that it is possible to achieve the high level of quality necessary for vaccine trials and natural history studies in a resource-limited setting and provide strategies for laboratories to monitor PBMC processing performance.

Increased circulating myeloid-derived suppressor cells correlate with clinical cancer stage, metastatic tumor burden, and doxorubicin-cyclophosphamide chemotherapy

Abnormal accumulation of myeloid-derived suppressor cells (MDSC) is an important mechanism of tumor immune evasion. Cyclophosphamide (CTX) has also been shown in non-tumor bearing animals to cause transient surges in MDSC. Knowledge of MDSC is primarily based on preclinical work, and to date only few published studies have involved cancer patients. The goal of this study was to test the hypothesis that circulating MDSC levels correlate with clinical cancer stage, CTX-based chemotherapy, and metastatic tumor burden. Whole blood was collected from 106 newly diagnosed solid tumor patients (stages I-IV). Percentages of circulating MDSC (Lin(-/Lo), HLA DR-, CD33(+)CD11b(+)) were determined prior to initiation of systemic therapy. In 17 early stage breast cancer patients receiving doxorubicin-cyclophosphamide chemotherapy every 14 days (ddAC) blood was collected on day 1 of each cycle. Circulating MDSC were significantly increased in cancer patients of all stages relative to healthy volunteers. A significant correlation between circulating MDSC and clinical cancer stage was also observed. Moreover, among stage IV patients, those with extensive metastatic tumor burden had the highest percent and absolute number of MDSC. Significant increases in circulating MDSC were observed with ddAC when compared with pretreatment levels. Circulating MDSC levels correlate with clinical cancer stage, ddAC, and metastatic tumor burden. This information must be incorporated into the design of future trials exploring immune-based therapeutic strategies. Pharmacologic modulation of MDSC should also be tested in future clinical trials.

Ten-color immunophenotyping of hematopoietic cells

Multicolor flow cytometry offers the unique ability to simultaneously assess and correlate multiple cellular properties at the single-cell level in a timely and efficient manner. Principles necessary for the development and evaluation of 10-color flow cytometry panels are discussed. The Basic Protocol outlines a simple and efficient method for the labeling of white blood cells with monoclonal antibodies directed against cell surface antigens. Alternate Protocol 1 incorporates the removal of plasma to allow the simultaneous assessment of surface light-chain expression on B cell populations. Alternate Protocol 2 describes a general method for the simultaneous assessment of surface and cytoplasmic antigens using a combination of fixation followed by membrane permeabilization. The methods were developed in a clinical laboratory setting for the description of normal pathways of hematopoietic maturation and the efficient identification of neoplastic hematopoietic cell populations, but the general principles should also be suitable for other applications.

Effects of delays in peripheral blood processing, including cryopreservation, on detection of CD31 expression on naive CD4 T cells

Delayed processing of peripheral blood or peripheral blood mononuclear cell isolation and cryopreservation can lead to the detection of somewhat higher levels of CD31 expression on naïve CD4 T cells by flow cytometry. These observations should be considered in the planning of multicenter clinical trials and in the interpretation of the results of functional studies.

Achieving donor-specific hyporesponsiveness is associated with FOXP3+ regulatory T cell recruitment in human renal allograft infiltrates

Exploring new immunosuppressive strategies inducing donor-specific hyporesponsiveness is an important challenge in transplantation. For this purpose, a careful immune monitoring and graft histology assessment is mandatory. Here, we report the results of a pilot study conducted in twenty renal transplant recipients, analyzing the immunomodulatory effects of a protocol based on induction therapy with rabbit anti-thymocyte globulin low doses, sirolimus, and mofetil mycophenolate. Evolution of donor-specific cellular and humoral alloimmune response, peripheral blood lymphocyte subsets and apoptosis was evaluated. Six-month protocol biopsies were performed to assess histological lesions and presence of FOXP3+ regulatory T cells (Tregs) in interstitial infiltrates. After transplantation, there was an early and transient apoptotic effect, mainly within the CD8+ HLADR+ T cells, combined with a sustained enhancement of CD4+ CD25(+high) lymphocytes in peripheral blood. The incidence of acute rejection was 35%, all steroid sensitive. Importantly, only pretransplant donor-specific cellular alloreactivity could discriminate patients at risk to develop acute rejection. Two thirds of the patients became donor-specific hyporesponders at 6 and 24 mo, and the achievement of this immunologic state was not abrogated by prior acute rejection episodes. Remarkably, donor-specific hyporesponders had the better renal function and less chronic renal damage. Donor-specific hyporesponsiveness was inhibited by depleting CD4+ CD25(+high) T cells, which showed donor-Ag specificity. FOXP3+ CD4+ CD25(+high) Tregs both in peripheral blood and in renal infiltrates were higher in donor-specific hyporesponders than in nonhyporesponders, suggesting that the recruitment of Tregs in the allograft plays an important role for renal acceptance. In conclusion, reaching donor-specific hyporesponsiveness is feasible after renal transplantation and associated with Treg recruitment in the graft.

Loss of T cell responses following long-term cryopreservation

Although cryopreservation of peripheral blood mononuclear cells (PBMC) is a commonly used technique, the degree to which it affects subsequent functional studies has not been well defined. Here we demonstrate that long-term cryopreservation has detrimental effects on T cell IFN-gamma responses in human immunodeficiency virus (HIV) infected individuals. Long-term cryopreservation caused marked decreases in CD4(+) T cell responses to whole proteins (HIV p55 and cytomegalovirus (CMV) lysate) and HIV peptides, and more limited decreases in CD8(+) T cell responses to whole proteins. These losses were more apparent in cells stored for greater than one year compared to less than six months. CD8(+) T cell responses to peptides and peptide pools were well preserved. Loss of both CD4(+) and CD8(+) T cell responses to CMV peptide pools were minimal in HIV-negative individuals. Addition of exogenous antigen presenting cells (APC) did not restore CD4(+) T cell responses to peptide stimulation and partially restored T cell IFN-gamma responses to p55 protein. Overnight resting of thawed cells did not restore T cell IFN-gamma responses to peptide or whole protein stimulation. A selective loss of phenotypically defined effector cells did not explain the decrement of responses, although cryopreservation did increase CD4(+) T cell apoptosis, possibly contributing to the loss of responses. These data suggest that the impact of cryopreservation should be carefully considered in future vaccine and pathogenesis studies. In HIV-infected individuals short-term cryopreservation may be acceptable for measuring CD4(+) and CD8(+) T cell responses. Long-term cryopreservation, however, may lead to the loss of CD4(+) T cell responses and mild skewing of T cell phenotypic marker expression.

Flow cytometric assessment of hematopoietic cell subsets in cryopreserved preterm and term cord blood, influence of obstetrical parameters, and availability for transplantation

OBJECTIVE

The aim of this study was to characterize the lymphocyte and the hematopoietic stem and progenitor cell (HPC) subsets of cryopreserved premature cord blood (PCB) compared to term cord blood (TCB) by flow cytometry, to study the influence of birth conditions, and to assess its availability for transplantation.

MATERIALS AND METHODS

Four-color flow cytometric analysis was performed on 43 PCB and 40 TCB cryopreserved samples using a panel of 24 different mAbs, directed against lymphoid and HPC surface markers. The CB volume was estimated by the weight of the newborn to determine the absolute MNC and CD34(+) cell content/CB sample. Clinical and obstetrical data were recovered. Statistical comparisons and a multiple regression analysis were performed.

RESULTS

No consistent differences were found in the mononuclear cell (MNC) or CD34(+) cell concentration (x10(6)/L) between PCB and TCB. The percentage of primitive HPC (CD34(+)CD38(-), CD34(+)CD38(-)CD90(-)HLA-DR(-), CD34(+)CD38(-)CD90(-)HLA-DR(+)) and primitive lymphoid progenitors (CD34(+)CD7(+), CD34(+)CD7(+)CD19(-)CD117(-)) were higher in PCB than in TCB. Correspondingly, TCB had an increased percentage of committed HPC. No sample of PCB contained >2 x 10(7) MNC/kg (and only 48% had >1 x 10(5) CD34(+) cells) for a recipient of 20 kg body wt, as the minimum threshold recommended for CB transplantation. Obstetrical factors modulated mainly lymphocyte subsets and fewer HPC subpopulations. Acute fetal distress increased CD34(+) cells, especially the immature subsets. Maternal treatment with dexamethasone and intrauterine growth retardation decreased CD3(+) cells. No other obstetrical factors played a detrimental effect on CB cells if used for transplantation.

CONCLUSION

PCB is richer in immature cells both in lymphocyte and HPC populations, and its use for transplantation, at least in special cases, should be reconsidered.

Comparison of methods for determining zeta-chain associated protein – 70 (ZAP-70) expression in patients with B-cell chronic lymphocytic leukemia (B-CLL)

BACKGROUND

Zeta-chain associated protein of 70kDa (ZAP-70) is the most promising surrogate marker for the immunoglobulin heavy chain variable region (IgV(H)) mutation status in B-cell chronic lymphocytic leukemia (B-CLL). Crespo et al. proposed the detection of ZAP-70 by flow cytometry. Recently several novel monoclonal antibodies appeared on market.

METHODS

We compared different staining methods utilizing monoclonal antibodies (moAb) against ZAP-70: anti-ZAP-70 PE, clone 1E7.2, anti-ZAP-70 PE, clone 17A/P-ZAP70 directly stained with flourochrome as well as anti-ZAP-70 antibody, clone 2F3.2 stained with Zenontrade mark Alexa Fluor(R) 488 Labeling Kit. Additionally different reagents for permeabilization such as IntraPrep, FIX & PERM, Perm/Wash and 70% ethanol/paraformaldehyde were used to find the most clinically relevant and easy assay to determine ZAP-70 expression in B-CLL. Moreover we compared results of ZAP-70 expression assessed by whole blood protocol with those obtained using-peripheral mononuclear cells isolated from whole blood.

RESULTS

Anti-ZAP-70 moAb clone 17A/P-ZAP70 gave elevated results for all B-CLL patients as well as healthy controls. Staining with anti-ZAP-70 moAb clone 1E7.2 and anti-ZAP-70 moAb clone 2F3.2 was effective in distinguishing negative and positive cells for ZAP-70 protein expression. Not statistically significant discrepancies of ZAP-70 expression were noticed between different fixation and permeabilization methods.

CONCLUSION

Basing on results obtained during this study we can recommend use of anti-ZAP-70 PE, clone 1E7.2 moAb utilizing whole blood protocol with commercial kits for permeabilization as an easy method that brings compatible results to the original method proposed by Crespo et al.

Immuno-monitoring of CD8+ T cells in whole blood versus PBMC samples

The study of natural T cell responses against pathogens or tumors, as well as the assessment of new immunotherapy strategies aimed at boosting these responses, requires increasingly precise ex vivo analysis of blood samples. For practical reasons, studies are often performed using purified PBMC samples, usually cryopreserved. Here, we report on FACS analyses of peripheral blood T cells, performed by direct antibody staining of non-purified total blood. For comparison, fresh PBMC, purified by Ficoll, were analysed. Our results show that the latter method can induce a bias in subpopulation distribution, in particular of CD8+ T cells, and sometimes lead to inaccurate measurement of antigen specific CD8+ T cell responses. Direct analysis of total blood can be applied to longitudinal immuno-monitoring of T cell-based therapy. While the need to purify and cryopreserve PBMC for subsequent studies is obvious, the use of whole blood has the advantage of providing unbiased results and only small amounts of blood are used.

Age-related alterations to immune parameters in Labrador retriever dogs

In order to assess age-related changes in the immune status of Labrador retriever dogs, leukocyte phenotypes, lymphocyte proliferative capacity, and serum antibody levels were measured in four cohorts of dogs, ranging from 2 to 10 years of age. Absolute numbers of white blood cells, lymphocytes, monocytes, granulocytes, and CD3+, CD4+, CD8+ and CD21+ lymphocytes significantly decreased with increasing age. Relative percentages of lymphocytes and CD4 cells were significantly decreased, and relative percentages of granulocytes and CD8 cells significantly increased, with age. The CD4:CD8 ratio showed a significant age-related decrease. Proliferative responses of T-cells to mitogens in whole-blood cultures either increased (Concanavalin A) or remained the same (phytohemagglutinin) with age when data was normalised to allow for differences in responding cell number. Similarly, normalised data of proliferative response to anti-CD3 stimulation together with phorbol 12-myristate 13-acetate showed an age-related increase. Serum levels of total IgA significantly increased with age whereas total IgG levels remained unchanged. These observations illustrate a significant change to a number of immune parameters with age. However, further work is required to determine whether the differences reported here are sufficient to cause overt or functional immune senescence in Labrador retriever dogs.

Alterations of T-lymphocyte populations in Parkinson disease

Immune reaction-related inflammation may be important in the pathogenesis of Parkinson disease (PD). To elucidate peripheral immunologic alterations in PD, we characterized extended peripheral T-lymphocyte populations in 33 patients with PD and 34 normal subjects. Patients with PD had significantly decreased CD4+:CD8(+)T-cell ratios (P<0.001), fewer CD4(+)CD25(+)T cells (P<0.01), and significantly increased ratios of IFN-gamma-producing to IL-4-producing T cells (P<0.001). The characteristics of predominant expression of CD8(+)T cells, depletion of CD4(+)CD25(high) cells, and a shift to a T(H)1-type immune response in the peripheral immune system in PD patients may reflect an immune reaction-associated inflammatory process in the brain.

Reference ranges of lymphocyte subsets of healthy adults in Turkey

The aim of this study was to determine the reference ranges of lymphocyte subsets in serologically HIV-negative healthy adults in Turkey.

MATERIALS AND METHODS

Blood samples from 220 healthy adults, 105 female and 115 male, collected into tubes containing EDTA were investigated for lymphocyte subsets using flow cytometry. The age range was 18-80 years (44.80 +/- 16.69).

RESULTS

The mean percentage and absolute values of the lymphocyte subsets were as follows: CD3: 72.70 +/- 8.44%, 1,680 +/- 528 cells/microl; CD4: 47.37 +/- 9.10%, 1,095 +/- 391 cells/microl; CD8: 28.99 +/- 5.99%, 669 +/- 239 cells/microl; CD19: 10.96 +/- 4.44%, 254 +/- 122 cells/microl and CD56: 7.03 +/- 3.26%, 161 +/- 92 cells/microl, respectively. The ratio of CD4/CD8 was 1.68 +/- 0.43. There was no statistically significant difference in the percentages and absolute values of lymphocyte subsets between the genders (p > 0.05).

CONCLUSION

Immunophenotyping has been used to establish reference values of lymphocyte subsets in normal healthy adults in Turkey.

Flow cytometry identification and characterization of mononuclear cell subsets in the neotropical primate Saimiri sciureus (squirrel monkey)

BACKGROUND

The neotropical primate squirrel monkey is used in many areas of biomedical research including neuroendocrinology, immunology and infectious diseases. However, research has been hampered by the lack of immunological tools for this primate.

METHODS

A series of 67 commercially available monoclonal antibodies to human CD antigens or cytokines were tested on Saimiri mononuclear cells and the specificity was assessed by double staining using flow cytometry.

RESULTS

Monoclonal antibodies defining the main mononuclear cells subsets (monocytes, B, T, including CD4 and CD8 T cells) as well as activation markers have been identified. The conditions to specifically identify the various cell subsets using two color flow cytometry and establish their relative proportions have been set-up. We also have established normal values of the main circulating mononuclear cell subsets for adult Saimiri sciureus monkeys from the breeding unit of Institut Pasteur in French Guiana. The distribution between spleen, blood and lymph nodes has been compared.

CONCLUSIONS

These tools allow documenting the phenotype of most Saimiri mononuclear cell subsets and assessing their activation level. This opens new perspectives for vaccinology and immunopathology research in this experimental non-human primate host, in particular for malaria research.

Regulatory CD4+CD25+ T lymphocytes in peripheral blood from patients with atopic asthma

The aim of this study was to analyze whether regulatory CD4+CD25+ T lymphocytes exist and function normally in patients with atopic asthma. Our data showed that a significant increase in CD4+CD25+ cell numbers was seen in atopic asthmatics during acute exacerbation, but not in those stable asthmatics, atopic nonasthmatics, and normal subjects. The mean inhibition values of the proliferation response of CD4+CD25- cells by CD4+CD25+ cells from normal controls and asthmatics were almost the same. There was no difference in inhibitory effects on both Th1 and Th2 cytokine production of CD4+CD25- cells by CD4+CD25+ cells in the two groups. These data demonstrated that although CD4+CD25+ cells increase in atopic asthma during exacerbation, these regulatory T cells appear to function normally with regard to suppression of T-cell proliferation as well as Th1-Th2 cytokine production.

Reference values for peripheral blood lymphocyte phenotypes applicable to the healthy adult population in Switzerland

OBJECTIVES

Use of domestic reference values is known to improve the accuracy of flow cytometric analysis by integrating local variation due to race, gender, and age. In the absence of previously published estimates, we now report establishment of reference values for a wide range of peripheral blood lymphocyte phenotypes applicable to the healthy adult population in Switzerland and other regions with similar demographic characteristics.

METHODS

A representative sample population was recruited from among well characterized local blood donors (n = 70) and quantitative multiparametric flow cytometry used to estimate absolute and proportional values for a range of T-, B-, and NK-cell subsets, including those associated with activation and maturity. Distribution-free methods were then applied to generate 95% reference values and to estimate the significance of gender and age-related differences.

RESULTS

Reference values were obtained for the absolute and proportional levels of total CD3(+) T cells (536-1787 cells/microL, 54.90-84.03%), helper CD4(+) T cells (309-1139 cells/microL, 32.53-62.88%), cytotoxic CD8(+) T cells (137-823 cells/microL, 11.55-38.60%), activated CD3(+) T cells expressing CD25 (7-94 cells/microL, 0.50-5.95%), CD38 (102-554 cells/microL, 5.98-26.80%), HLA-DR (18-186 cells/microL, 1.25-9.68%) or CD38/HLA-DR (4-52 cells/microL, 0.30-2.30%), activated CD4(+) T cells expressing CD25 (7-52 cells/microL, 0.33-2.80%), CD38 (69-547 cells/microL, 6.13-32.20%), HLA-DR (11-55 cells/microL, 0.80-4.43%) or CD38/HLA-DR (4-22 cells/microL, 0.30-1.35%), activated CD8(+) T cells expressing CD25 (0-12 cells/microL, 0.00-0.69%), CD38 (13-124 cells/microL, 0.93-7.03%), HLA-DR (6-108 cells/microL, 0.33-6.38%) or CD38/HLA-DR (2-47 cells/microL, 0.13-2.68%), naive CD4(+) T cells expressing CD45RA(+)/CD62L(+) (84-761 cells/microL, 9.48-41.88%), naive CD8(+) T cells expressing CD45RA(+)/CD62L(+) (42-360 cells/microL, 3.68-19.23%), memory CD4(+) T cells expressing CD45RO(+) (247-807 cells/microL, 16.50-42.15%), memory CD8(+) T cells expressing CD45RO(+) (72-377 cells/microL, 3.78-22.80%), B-cells expressing CD19 (72-460 cells/microL, 4.70-19.13%) or CD20 (66-529 cells/microL, 4.63-21.00%), total CD3(-)/(CD16(+)/CD56(+)) NK-cells (77-427 cells/microL, 5.35-30.93%), and activated NK-cells expressing CD25 (0-10 cells/microL, 0-0.50%) or HLA-DR (3-99 cells/microL, 0.20-7.28%).

CONCLUSION

It is anticipated that availability of localized reference values for an extended range of peripheral blood lymphocyte phenotypes should supplement previously published reference values and enhance the utility of flow cytometric analysis undertaken in Switzerland.

Fixation and cryopreservation of whole blood and isolated mononuclear cells: Influence of different procedures on lymphocyte subset analysis by flow cytometry

BACKGROUND

Immunophenotyping of whole blood (WB) and isolated peripheral blood mononuclear cells (PBMCs) is a common tool used to evaluate immune system changes in clinical studies. The development of methods that would allow preservation of samples for flow cytometric analysis is important for the extension of this technology to field testing in settings where the equipment might be not readily accessible.

METHODS

Three-color flow cytometric analysis was used to determine percentages of T cells and their subsets (CD3(+), CD4(+), CD8(+)), B cells (CD19(+)), and natural killer cells (CD16(+)/56(+)) in WB and PBMCs using variations of a standard stain/fix WB staining procedure (Optilyse) that included staining following fixation and freezing of fixed samples before or after staining.

RESULTS

Comparable lymphocyte subset percentages in WB or PBMCs were observed regardless of Optliyse method used (all Ps >/= 0.8). However, differences in fluorescence intensity for several markers were observed across procedures. Compared with the standard stain/fix procedures, fix/stain decreased the mean fluorescence intensities for CD4, CD8, CD19 and CD16/56 in WB and PBMCs (P </= 0.03 for these markers P = 0.105 for CD8 in PBMCs). Further decreases in mean fluorescence intensity were seen with the fix/stain/freeze procedure. The stain/fix/freeze yielded intensities largely comparable to those seen with standard stain/fix procedure (P >/= 0.13), suggesting that, when the markers of interest are known at the time of field collection, implementation of this procedure might be desirable. Fix/freeze/stain resulted in diminution of intensity in general, but they tended to be more modest than those seen for fix/stain/freeze and therefore might be applicable to field studies in instances when the specific markers of interest cannot be defined upfront.

CONCLUSIONS

Freezing of fixed WB and PBMCs before or after cell surface staining is a reliable method for preserving specimens in field sites for later determination of lymphocyte subset percentages, which are commonly assessed in immunodeficient and cancer patients.

Effects of cryopreservation on lymphocyte immunophenotype and function

Cryopreservation of isolated peripheral blood mononuclear cells (PBMCs) for phenotypic and functional analyses is considered a standard procedure in order to minimize operator-dependent inter-assay variability and to optimize the use of available resources. However, only few and somewhat conflicting data are presently available on the effects of cryopreservation on PBMCs, especially in samples from HIV-infected patients in which assessment of lymphocyte phenotype and function is of the outmost importance. In this study, we compared fresh versus frozen/thawed (F/T) samples isolated from 19 healthy individuals and 21 HIV-infected patients, showing that cryopreservation induces: (i) a profound decrease of CD62L expression, with a consequent significant decline of the calculated proportions of "naïve" (CD45RA+CD62L+) and "central memory" (CD45RO+CD62L+) T cells; (ii) an increase of the calculated proportions of "effector" CD8+ T cells (CD45RA+CD62L- and CD45RO+CD62L-) in the healthy subjects, while no changes were observed in the HIV-infected group; (iii) a significant decline of CC chemokine receptor 5 (CCR5) expression; (iv) a loss of proliferative responses to some HIV antigens (i.e. p24) and recall antigens [cytomegalovirus (CMV) and Influenza] in HIV-infected patients. We thus conclude that cryopreservation induces a consistent set of changes in PBMCs from both healthy and HIV-infected individuals, and that certain immunological studies of HIV-infected patients (i.e. studies of immune reconstitution following antiretroviral therapy in HIV-infected patients or studies of HIV-infectivity in vitro using CCR5-tropic strains) should be performed on fresh samples.

Expression of adhesion molecules on T lymphocytes in young children and infants--a comparative study using whole blood lysis or density gradient separation

We investigated the use of two sample preparation techniques (whole blood lysis [WBL], and Ficoll-Hypaque density separation [FDS]) for flow cytometric estimation of adhesion molecule (CD54, CD62L and CD11b) expression on T lymphocytes from children less than 2 years old, comparing the results with normal adult controls. Using WBL methods, young children had lower percentages of CD3+/CD54+ and CD3+/CD11b+ lymphocytes, but not of CD3+/CD62L+ lymphocytes than adult controls. FDS was associated with significantly higher percentages of CD3+/CD62L+ and CD3+/CD11b+ lymphocytes in young children and adults alike, while the percentages of CD3+/CD54+ cells from adults was not affected by FDS. The percent expression of CD54, CD62L, and CD11b on T cells from both children and adults were significantly higher following FDS, with a greater increase in CD11b expression on T cells from young children, reaching adult levels. The mean fluorescence intensity (MFI) of CD62L on T cells from young children, which was lower than that of adults using WBL preparation, was significantly higher following FDS, reaching adult levels. The higher levels of adhesion molecule expression associated with FDS did not result from T-cell activation, as assessed by CD69, CD25, and HLA-DR expression. Thus, adhesion molecule expression on T lymphocytes from young children is more sensitive to modification by isolation procedures than that on adult T cells. Caution should therefore be exercised in interpreting adhesion molecule expression data on T cells from children.

Expression of peripheral blood lymphocyte muscarinic cholinergic receptor subtypes in airway hyperresponsiveness

The expression of muscarinic cholinergic receptor subtypes was investigated in peripheral blood lymphocytes (PBL) of bronchial asthma patients by a combined kinetic and equilibrium labeling technique for radioligand binding assay of muscarinic cholinergic receptor subtypes and by receptor immunochemistry and immunocytochemistry. An increased expression of M2 and to a lesser extent of M5 receptors and no changes of M4 receptor were observed in PBL of asthmatics compared to control individuals. The increase was related to bronchial hyperresponsiveness detected by methacholine challenge test. Analysis of M3 receptor expression revealed biphasic changes, with a decreased receptor density in patients with normal, mild and moderate responses to methacholine test and a recovery to levels similar to those found in healthy individuals in severe responders to methacholine test. The demonstration of a different expression of lymphocyte muscarinic receptors in asthma suggests that cholinergic system may participate to a molecular framework influencing immune functions in asthma.

Treatment with methylprednisolone in relapses of multiple sclerosis patients: immunological evidence of immediate and short-term but not long-lasting effects

Relapses of multiple sclerosis (MS) are treated commonly with high-dose intravenous methylprednisolone (MP) given over a period of 3-5 days. The mechanisms responsible for the beneficial effects of MP in attacks are not clearly established. It is also controversial whether this treatment may have a long-term effect. Here, peripheral blood samples from relapsing--remitting MS patients in acute relapse were analysed by flow cytometry just before steroid treatment and at different time points after initiation of the therapy. We observed an immediate (day 3) decrease in the percentage of CD4+ lymphocytes, with a relative increase in the memory (CD4+CD45R0+) subpopulation. A longer standing effect of MP on IFN-gamma production, CD54, CCR5, CXCR3 and CD95 (Fas) expression was also observed on CD4+ cells after 1 month of treatment initiation. Six months after the therapy, during clinical remission, no changes due to ivMP therapy were detected. These results support that MP treatment of relapses induces immediate post-treatment and short-term effects on the immune system that could partly account for the clinical and radiological improvement observed in MS patients. However, no conclusion can be drawn as to a possible long-term or even intermediate influence of ivMP treatment on the course of the disease.

Lymphocyte subsets in peripheral blood of dogs--a flow cytometric study

Slight differences in the results of papers describing lymphocyte subsets distribution in the peripheral blood of healthy dogs may be explained by differences in monoclonal antibody clones and sources, breed and age of animals examined, methods of sample treatment, or methods of result analysis. In this paper, we described the effect of sample processing and of sample storage as well as the effect of age, breed, and gender of dogs on lymphocyte subset distribution. No significant differences were found between samples processed following a whole-blood lysis method and samples processed after density gradient separation. Furthermore, no significant differences were found between samples processed within 2h after collection and those stored at 4 degrees C for 12-16 h before processing. Age-related changes were evident in lymphocyte subset distribution in the peripheral blood of 38 Beagles divided according to their age into the six groups: (1) 5-6 days; (2) 2 months; (3) 6 months; (4) 1-2 years; (5) 3-5 years; and (6) >5 years. The percentage of B-lymphocytes (CD21-like positive cells) in the peripheral blood of newborn pups was 39.5+/-5.7 and decreased with advancing age. The percentage of CD8+ lymphocytes was 7.7+/-3.4 after birth and increased with advancing age. No age-related changes were observed in the percentages of CD4+ lymphocytes. The CD4+:CD8+ ratio decreased with advancing age. No significant age-related change was observed for lymphocytes bearing the gammadelta-TCR. Some breed differences were evident. Adult (1-5-year-old) Beagles, German Shepherds, Dalmatians, and Dachshunds were examined. The percentages of lymphocytes were higher in Beagles and Dachshunds than in Dalmatians and German Shepherds. The highest and the lowest absolute lymphocyte counts were found in Beagles and German Shepherds, respectively. As a consequence, German Shepherds showed the lowest absolute counts of the individual lymphocyte subpopulations and the widest neutrophil:lymphocyte ratio. Dalmatians showed the lowest percentage of CD3+ cells, the highest percentage of CD21+ cells, and the lowest CD4+:CD8+ ratio. German Shepherds showed the lowest percentage of CD21+ cells and the highest CD4+:CD8+ ratio. Females in Beagles and Dachshuns had nonsignificantly higher percentages of total lymphocytes, CD3+, CD4+, and nonsignificantly lower percentages of CD21+ lymphocytes. We concluded that there are age-, breed-, and perhaps also gender-related differences in lymphocyte subset distribution in the peripheral blood of dogs. Therefore, there is need to use appropriate control group in the experimental protocols. Among-breed differences could explain, at least partly, breed predisposition for some diseases.

Intra-CNS activation by antigen-specific T lymphocytes in experimental autoimmune encephalomyelitis

Identification and quantitation of autoreactive T lymphocytes is crucial in order to understand the pathogenesis of autoimmune diseases. We used flow cytometry to analyze autoantigen-specific T cellular responses in the well characterized rat experimental autoimmune encephalomyelitis (EAE) model. Cells isolated from both the central nervous system (CNS) tissue and peripheral lymph nodes were analyzed directly ex vivo or after short term in vitro culture with specific autoantigen. CNS infiltrating T lymphocytes displaying an interferon-gamma response to selected encephalitogenic myelin protein epitopes were measured kinetically during an individual disease episode and also between relapses in a chronic rat EAE model. One of the EAE models used displays a restriction towards TCRBV8S2 chain usage by the encephalitogenic T cells. In this model, in vitro production of intracellular interferon-gamma was selectively detected within this T cell subset derived from both the CNS and peripheral lymph nodes. Furthermore, antigen-specific cells infiltrating the CNS in this model produced several-fold higher amounts of interferon-gamma upon antigen stimulation and displayed a significantly increased in vivo proliferation compared with peripheral lymphocytes. These data thus directly demonstrates that T cells stimulated by a specific autoantigen in the periphery primarily acquire effector functions in the cellular environment of the target organ of the autoantigen.

Patients with inflammatory bowel disease (IBD) reveal increased induction capacity of intracellular interferon-gamma (IFN-gamma) in peripheral CD8+ lymphocytes co-cultured with intestinal epithelial cells

Intestinal epithelial cells seem to play a key role during IBD. The network of cellular interactions between epithelial cells and lamina propria mononuclear cells is still incompletely understood. In the following co-culture model we investigated the influence of intestinal epithelial cells on cytokine expression of T cytotoxic and T helper cells from patients with IBD and healthy controls. Peripheral blood mononuclear cells (PBMC) were purified by a Ficoll-Hypaque gradient followed by co-incubation with epithelial cells in multiwell cell culture insert plates in direct contact as well as separated by transwell filters. We used Caco-2 cells as well as freshly isolated colonic epithelia obtained from surgical specimens. Three-colour immunofluorescence flow cytometry was performed after collection, stimulation and staining of PBMC with anti-CD4, anti-CD8, anti-IFN-gamma and anti-IL-4. Patients with IBD (Crohn's disease (CD), n = 12; ulcerative colitis (UC), n = 16) and healthy controls (n = 10) were included in the study. After 24 h of co-incubation with Caco-2 cells we found a significant increase of IFN-gamma-producing CD8+ lymphocytes in patients with IBD. In contrast, healthy controls did not respond to the epithelial stimulus. No significant differences could be found between CD and UC or active and inactive disease. A significant increase of IFN-gamma+/CD8+ lymphocytes in patients with UC was also seen after direct co-incubation with primary cultures of colonic crypt cells. The observed epithelial-lymphocyte interaction seems to be MHC I-restricted. No significant epithelial cell-mediated effects on cytokine expression were detected in the PBMC CD4+ subsets. Patients with IBD-even in an inactive state of disease-exert an increased capacity for IFN-gamma induction in CD8+ lymphocytes mediated by intestinal epithelial cells. This mechanism may be important during chronic intestinal inflammation, as in the case of altered mucosal barrier function epithelial cells may become targets for IFN-gamma-producing CD8+ lymphocytes.

Maturational changes of lymphocyte surface antigens in human blood: comparison between fetuses, neonates and adults

The objective of this study was to investigate the maturational changes of lymphocyte surface antigens during ontogeny from fetuses to adults using the proven whole blood lysis technique. Two-color flow cytometric analysis of lymphocyte surface markers was performed on 20 fetal blood samples obtained by cordocentesis, 70 cord blood and 30 adult blood samples. The leukocyte count and all T-cell subsets were highest in neonates compared to fetuses and declined into adulthood. In contrast, the percentage of CD2+ T cells (fetal blood 57% versus adult blood 82%; p </= 0.001), CD3+ T cells (fetal blood 52% versus adult blood 77%; p </= 0.001), CD4+ T cells (fetal blood 39% versus adult blood 50%; p </= 0.05) and CD8+ T cells (fetal blood 15% versus adult blood 24%; p </= 0.001) showed a significant increase from fetuses to adults. The absolute and relative amounts of B cells were highest in fetuses (fetal blood 547 x 10(6)/l, 18%) followed by a steady decline to adulthood (adult blood 243 x 10(6)/l, 13%; p </= 0.001). The discordance between the absolute and relative size of lymphocyte subpopulations emphasizes the consideration of both variables in the assessment of lymphocyte maturation. The presented data may contribute to a better knowledge of the maturation of the immune system.

Preservation of lymphocyte immunophenotype and proliferative responses in cryopreserved peripheral blood mononuclear cells from human immunodeficiency virus type 1-infected donors: implications for multicenter clinical trials. The ACTG Immunology Advanced Technology Laboratories

Human immunodeficiency virus type 1 (HIV-1) infection results in impaired immune function that can be measured by changes in immunophenotypically defined lymphocyte subsets and other in vitro functional assays. These in vitro assays may also serve as early indicators of efficacy when new therapeutic strategies for HIV-1 infection are being evaluated. However, the use of in vitro assays of immune function in multicenter clinical trials has been hindered by their need to be performed on fresh specimens. We assessed the feasibility of using cryopreserved peripheral blood mononuclear cells (PBMC) for lymphocyte immunophenotyping and for lymphocyte proliferation at nine laboratories. In HIV-1-infected patients with moderate CD4(+) lymphocyte loss, the procedures of density gradient isolation, cryopreservation, and thawing of PBMC resulted in significant loss of CD19(+) B cells but no measurable loss of total T cells or CD4(+) or CD8(+) T cells. No significant changes were seen in CD28(-) CD95(+) lymphocytes after cell isolation and cryopreservation. However, small decreases in HLA-DR(+) CD38(+) lymphocytes and of CD45RA(+) CD62L(+) were observed within both the CD4(+) and CD8(+) subsets. Fewer than 10% of those specimens that showed positive PBMC proliferative responses to mitogens or microbial antigens lost their responsiveness after cryopreservation. These results support the feasibility of cryopreserving PBMC for immunophenotyping and functional testing in multicenter AIDS clinical trials. However, small changes in selected lymphocyte subsets that may occur after PBMC isolation and cryopreservation will need to be assessed and considered in the design of each clinical trial.