Detecting cytokine production at the single-cell level

Flow cytometric analysis of Th1 and Th2 cytokines in PBMCs as a parameter of immunological dysfunction in patients of superficial transitional cell carcinoma of bladder

Transitional cell carcinoma (TCC) is the commonest cancer of the bladder. Although majority of TCC can be diagnosed at an early stage and removed easily by transurethral resection of tumor (TURT), the management of this carcinoma is complicated due to frequent recurrences usually within 6 months to one-year period. An imbalance between the Th1 and Th2 immune responses has been attributed to immune dysregulation in various malignancies. The present study aims to evaluate the Th1 and Th2 balance in Peripheral Blood Mononuclear Cells of 41 TCC patients (20 recurrent and 21 non-recurrent) using flow cytometry. It also further assesses immunological and cellular factors influencing the anti-neoplastic activity of the TCC patients and in 21 normal healthy subjects in terms of their cytokine expression and various cell surface markers. The findings of the study revealed that the cell surface markers CD3+, CD4+ and CD8+ along with NK cells were found to be significantly lower in patients than healthy controls (p < 0.01). The mean percent expression of CD4+ was significantly lower in patients showing recurrence (23.9 +/- 9.84) as compared to patients with non-recurrence (31.1 +/- 12.27). The percentage of CD4+T-cells (mean +/- SD) producing IFN-gamma, IL-2 and TNF-alpha were statistically significantly reduced in patients (19.1 +/- 4.94, 52.3 +/- 20.86 and 12.8 +/- 4.49) as compared to healthy controls (23.3 +/- 3.67, 67.5 +/- 12.0 and 17.6 +/- 5.96 respectively), (p < 0.01, 0.018, 0.001). On the contrary, the mean levels of IL-4, IL-6 and IL-10 in patients (63.8+/-17.01, 60.4+/-14.79 and 65.7 +/- 14.84 respectively) were significantly higher as compared to healthy controls (24.4 +/- 8.77, 26.5 +/- 5.28 and 20.6 +/- 3.81 respectively), (p < 0.001). No statistically significant difference was observed in the cytokine expression between patients showing recurrence and non-recurrence. Patients with bladder cancer seem to develop a Th2 dominant status with a deficient type1 immune response. The lymphocyte evaluation along with cytokine measurement can provide a sensitive and valuable tool for evaluating the function of cell-mediated immunity in these patients and can also find application in therapeutic monitoring of bladder cancer patients as new targets for immunotherapy.

Patterns of intracellular cytokines in CD4 and CD8 T cells from patients with mycobacterial infections

Using a short-term bulk culture protocol designed for an intracellular-staining method based on a flow cytometry approach to the frequencies of cytokine-producing cells from tuberculosis and leprosy patients, we found distinct patterns of T cell subset expression. The method also reveals the profile of peak cytokine production and can provide simultaneous information about the phenotype of cytokine-producing cells, providing a reliable assay for monitoring the immunity of these patients. The immune response of Mycobacterium leprae and purified protein derivative (PPD) in vitro to a panel of mycobacteria-infected patients from an endemic area was assessed in primary mononuclear cell cultures. The kinetics and source of the cytokine pattern were measured at the single-cell level. IFN-gamma-, TNF-alpha-, IL-4- and IL-10-secreting T cells were intracytoplasmic evaluated in an attempt to identify M. leprae- and PPD-specific cells directly from the peripheral blood. The analysis by this approach indicated that TNF-alpha was the first (8 h) to be produced, followed by IFN-gamma (16 h), IL-10 (20 h) and IL-4 (24 h), and double-staining experiments confirmed that CD4+ were a greater source of TNF-alpha than of CD8+ T cells (P < 0.05). Both T cell subsets secreted similar amounts of IFN-gamma. We conclude that the protocol permits rapid evaluation of cytokine production by different T cell populations. The method can also be used to define immune status in non-infected and contact individuals.

Use of Leu3a/3b for the accurate determination of CD4 subsets for measurement of intracellular cytokines

BACKGROUND

Identification of human T-helper cell subsets is possible by measurement of intracellular cytokines after coincubation of lymphocytes with phorbol myristate acetate (PMA), calcium ionophore, and brefeldin A for up to 20 h. However, exposure to PMA leads to internalization of membrane CD4 and to loss of resolution of the CD4+ cells. Detection of CD3+CD8- cells or preselection of CD4+ cells prior to stimulation is more cumbersome than direct measurement of CD4+ cells. We report the use of the Leu3a/Leu3b multiclone for the accurate determination of CD4 cells after PMA stimulation.

METHODS

Peripheral blood lymphocytes were isolated from healthy normal donors and the proportion of CD3+ / CD4+ T cells was determined by flow cytometry before and after incubation with PMA, calcium ionophore, and brefeldin A for 20 h using a variety of anti-CD4 monoclonal antibodies.

RESULTS

The Leu3a/3b multiclone reagent was the only anti-CD4 monoclonal antibody capable of resolving more than 98% of the initial CD4+ events after incubation with PMA.

CONCLUSIONS

The higher signal-to-noise ratio associated with Leu3a3b reagent, compared with other CD4-specific antibodies available, allows the direct and accurate identification of the CD4 subset even after PMA treatment of cells.

Measurement of intracellular interferon-gamma and interleukin-4 in whole blood T lymphocytes from patients with systemic lupus erythematosus

Contradictory data are available about the dominance of T-helper 1 (T(H)1), or T-helper 2 (T(H)2) cytokines in systemic lupus erythematosus (SLE). Therefore, intracellular interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) production of T lymphocytes was measured in whole blood of healthy donors and active and inactive SLE patients by flow cytometry. The percentage of IFN-gamma and IL-4 positive cells was low (<1%) in unstimulated samples of the healthy controls, while that of IFN-gamma and IL-4 positive cells in the stimulated cells was 25.2+/-10.6% and 0.6+/-1.5%, respectively. No significant difference was found between SLE patients and healthy controls and between active and inactive patients in these parameters either in the unstimulated or in the stimulated samples. One patient with severe disease had as high as 11.8% IL-4 positive cells and 12.5% IFN-gamma positive cells in the stimulated samples, but after the initiation of intensive corticosteroid and cytostatic therapy, the percentage of IL-4 positive T cells decreased (4.76%) while that of IFN-gamma positive T cells increased (47.91%). We conclude that the intracellular IL-4 and IFN-gamma expression of T lymphocytes does not differ markedly between SLE patients and healthy controls, with the possible exception of severe disease, when marked IL-4 overproduction may exist beside low IFN-gamma production. Furthermore, corticosteroid and cytostatic therapy might normalize this altered IFN-gamma/IL-4 ratio.

Flow cytometric analysis of intracellular IFN-gamma, IL-4 and IL-10 in CD3(+)4(+) T-cells from rat spleen

The application of multi-parameter flow cytometry for the assessment of T-cell and cytokine functioning has been used by several groups for studying human and mouse samples, although little has been reported for the rat. Here we report the optimisation of immunofluorescent staining for cell surface and intracellular antigens using three-colour flow cytometric analysis to measure the frequency of rat CD3(+)4(+) T-cells that produce IFN-gamma, IL-4 and IL-10. In vitro stimulation of IFN-gamma production required incubation of splenocytes with PMA and ionomycin in the presence of the protein transport inhibitor brefeldin A for 6 h. Three stimulation protocols for IL-4 and IL-10 production were evaluated. In vitro priming of splenic T-cells with antibodies against CD3 and CD28 and recombinant cytokines (IL-2 and IL-4) for 5 days followed by restimulation with PMA and ionomycin was required to stimulate cells to produce either IL-4 or IL-10. Brefeldin A was found to be a more suitable protein transport inhibitor than monensin. This method will be useful for analysing the nature of individual rat cytokine-producing cells in a variety of experimental model systems.

Elevated interleukin-12 in progressive multiple sclerosis correlates with disease activity and is normalized by pulse cyclophosphamide therapy

Multiple sclerosis is postulated to be a Th1-type cell-mediated autoimmune disease. We investigated cytokine profiles in patients with progressive multiple sclerosis by using intracytoplasmic staining. We found increased IL-12 production by monocytes and increased IFN-gamma production by T cells in untreated patients as compared with controls. In patients treated with methotrexate, methylprednisolone, or cyclophosphamide/methylprednisolone (CY/MP), only CY/MP treatment normalized the elevated IL-12 production. Furthermore, CY/MP-treated patients had decreased IFN-gamma and increased IL-4, IL-5, and TGF-beta expression. Patients followed prospectively before and after starting CY/MP treatment showed a gradual decrease in IL-12 and IFN-gamma production and an increase in IL-4 and IL-5. In vitro, addition of 4-hydroperoxycyclophosphamide, a metabolite of cyclophosphamide decreased IL-12 production in mononuclear cell cultures. When patients were classified as having active or stable disease, IL-12 production correlated with disease activity. In summary, our results demonstrate a Th1-type cytokine bias in peripheral blood mononuclear cells of untreated progressive MS patients that is reversed by CY/MP treatment and is associated with Th2 and TGF-beta (Th3) type responses. These findings provide a basis for immune monitoring of patients with MS and suggest that treatments that downregulate IL-12 may prove to be beneficial in progressive MS.

Single-cell cytokine profiles in normal humans: comparison of flow cytometric reagents and stimulation protocols

Cytokines are produced and function at a micro environmental level: intracellular assessment has only recently become practically feasible. We used 3-color flow cytometry to examine surface and cytoplasmic antigens on peripheral blood lymphocytes of 18 normal donors, assessing the applicability/comparability of various directly conjugated anti-human cytokine reagents and stimulation protocols using separated cells or whole blood preparations. Interdonor variability far exceeded variability due to reagent or stimulation and separation techniques. Based on all results with various reagents, post 4-5.5 h stimulation with PHA/PMA/ionomycin, the range of the percents of T lymphocytes producing various cytokines included: gamma-IFN-13.2-65.0%, IL-2-10.0-56.7%, and TNF-alpha-17.1-79.2%. Compared to CD8+ cells, CD4+ cells more often expressed IL-2 (mean 45.7% of CD4 + vs. 21.4% of CD8+ p < 0.0001), less often expressed gamma-IFN (18.5% vs. 55.3%, p < 0.0001), and did not differ in TNF-alpha expression (52.9% vs. 59.4%). Of T cells producing gamma-IFN, 64.8-100.0% also produced TNF-alpha 3.5-100.0%, IL-2. Of T cells producing IL-2, 6.0-63.9% also produced gamma-IFN and 37.6-100.0%, TNF-alpha. These results demonstrate the broad spectrum of cytokine patterns in normal human adults, as well as the usefulness and limitations of various currently available cytokine products.

Flow-cytometric assessment of in vivo cytokine-producing monocytes in HIV-infected patients

We have used two-color flow cytometry to study in vivo monocytic cytokine production at the single-cell level in HIV-infected patients. We demonstrated the presence of intracellular IL-1 alpha, IL-1 beta, IL-1ra, and TNF alpha in circulating CD14+ monocytes from HIV-infected patients. The specificity of intracellular staining with anti-cytokine antibodies was demonstrated by the suppression of the fluorescent signal when staining was performed in the presence of recombinant cytokines. We did not detect any specific intracellular staining when anti-IL-4 antibodies were used since monocytes do not produce IL-4. In vivo intracellular cytokine production of IL-1 alpha, IL-1 beta, IL-1ra, and TNF alpha was higher in monocytes from HIV-infected individuals compared to monocytes from healthy controls; however, only the data concerning IL-1 alpha reached statistical significance. Monocytic cytokines are involved in the regulation of HIV gene expression and may participate in the modulation of the Th1/Th2 balance. The ability to follow the production of a wide range of cytokines by circulating monocytes of HIV-infected patients should allow one to better analyze the role of monocytic cytokines in the pathogenesis of HIV disease.

Detection of soluble T cell receptor-releasing cells by ELISPOT assay

A specific and sensitive enzyme-linked immunospot (ELISPOT) assay has been developed for the detection and enumeration of soluble T cell receptor (TCR)-releasing cells. Using this method, we readily detected at the single cell level the release of soluble TCR by living T lymphoma cells (MT-2 and HSB-2) but not by human B lymphoma cells (DAKIKI), mouse hepatoma cells (MH134) and dead MT-2. Furthermore, distinct spots in MT-2 cell culture were not visualized using several monoclonal antibodies against antigens unrelated to TCRs as a primary antibody. The specific and quantitative detection of soluble TCR-releasing cells using ELISPOT assay will certainly provide a valuable tool to better characterize soluble TCRs and their relationship to immune regulation and a number of diseases.

Detection of intracellular cytokines by flow cytometry

During the last years it has become increasingly clear that production of most cytokines is not confined to one cell type. Thus, a method to detect cytokines at the single cell level would be a helpful tool to study the contribution of different cells to cytokine production in heterogeneous cell populations. Recently, Sander et al. (1991) demonstrated that it is possible to detect intracellular cytokines by fixation with paraformaldehyde, permeabilization with saponin and subsequent indirect immunofluorescent staining using fluorescence microscopy. Here, we describe a modified method to increase the specific intracellular staining which enables us to detect IFN-gamma, IL-2 and IL-4 producing cells by single laser flow cytometry. The carboxylic ionophore monensin was used to interrupt intracellular transport processes leading to an accumulation of the cytokine in the Golgi complex. This resulting increase of the signal/noise ratio permitted us to detect weakly fluorescent cells such as IL-4 producing cells. While IL-4 was detected in approximately 1-3% of peripheral mononuclear cells from healthy donors, up to 30% of the cells produced IFN-gamma and nearly 50% IL-2 after phorbol ester and ionomycin stimulation. Microscopic and flow cytometric analysis showed a highly significant correlation. Using three-color flow cytometry it was possible to measure intracellular cytokines and cell surface markers simultaneously. Subpopulations of human T cells (e.g., CD4+ CD45R0-) producing a restricted cytokine pattern could be identified by cell surface staining and were characterized by their cytokine production. Consequently, there was no further need for cell sorting to determine cytokine producing subsets in heterogeneous cell populations. We have tested human T cell clones for intracellular cytokine production and found a high concordance to ELISA analysis of the supernatants. We conclude that detection of intracellular cytokines by flow cytometry is a rapid, easy and semiquantitative assay which may be used to study individual cells in heterogeneous populations as well as to screen homogeneous cells for their cytokine pattern. This method is particularly relevant in view of the accumulating evidence of the functional role that subsets of (T) cells may play in various diseases depending on the pattern of cytokines they produce.