Simultaneous production of interleukin 2, interleukin 4 and interferon-gamma by activated human blood lymphocytes

T-Cell Immunity in COVID-19-Recovered Individuals and Individuals Vaccinated with the Combined Vector Vaccine Gam-COVID-Vac

The COVID-19 pandemic has required extensive research on the new coronavirus SARS-CoV-2 and the creation of new highly effective vaccines. The presence of T-cells in the body that respond to virus antigens suggests adequate antiviral immunity. We investigated T-cell immunity in individuals who recovered from mild and moderate COVID-19 and in individuals vaccinated with the Gam-COVID-Vac combined vector vaccine. The ELISPOT method was used to determine the number of T-cells responding with IFN-γ synthesis to stimulation by peptides containing epitopes of the S-protein or N-, M-, ORF3, and ORF7 proteins, using peripheral blood mononuclear cells (PBMCs). At the same time, the multiplex method was used to determine the accumulation of IFN-γ and other cytokines in the culture medium. According to the data obtained, the proportion of positive conclusions about the T-cell immune response to SARS-CoV-2 antigens in control, recovered, and vaccinated individuals was 12%, 70%, and 52%, respectively. At the same time, more than half of the vaccinated individuals with a T-cell response were sensitized to the antigens of N-, M-, ORF3, and ORF7 proteins not produced by Gam-COVID-Vac, indicating a high likelihood of asymptomatic SARS-CoV-2 infection. Increased IFN-γ release by single sensitized T-cells in response to specific stimulation in recovered and vaccinated individuals did not result in the accumulation of this and other cytokines in the culture medium. These findings suggest a balance between cytokine production and utilization by immunocompetent cells as a prerequisite for providing a controlled cytokine signal and avoiding a "cytokine storm".

A novel phycobiliprotein alleviates allergic airway inflammation by modulating immune responses

RATIONALE

it has been claimed that phycocyanin exhibits pharmaceutical functions in inhibiting histamine release and leukotriene biosynthesis. In allergic asthma, these inflammatory mediators are crucial for disease progression.

OBJECTIVES

the aim of this study was to evaluate the therapeutic potential of R-phycocyanin (R-PC) against allergic airway inflammation.

METHODS

mouse bone marrow-derived dendritic cells (BMDCs) were used to evaluate the immunomodulatory functions of R-PC. In addition, an airway inflammatory model was used to evaluate the therapeutic potential of R-PC.

MEASUREMENTS AND MAIN RESULTS

R-PC treatment resulted in a decrease of endocytosis, increase of costimulatory molecule expression, and enhancement of interleukin-12 production in mouse BMDCs. Moreover, R-PC-treated cultured dendritic cells were able to promote CD4(+) T-cell stimulatory capacity and increase interferon-γ expression in CD4(+) T cells. Intraperitoneal administration of R-PC suppressed ovalbumin (OVA)-induced airway hyperresponsiveness, serum levels of OVA-specific IgE and IgG1, eosinophil infiltration, Th2 cytokine levels, and eotaxin in bronchoalveolar lavage fluid of mice. Antibody against Toll-like receptor-4 was able to inhibit R-PC-induced IL-12 p70 production. Moreover, inhibition of nuclear factor-κB (NF-κB) by helenalin and inhibition of the JNK pathway by JNK inhibitor II inhibited R-PC-induced IL-12 p70 production. Western blotting and electrophoretic mobility shift assays showed that R-PC augmented phosphorylation of the inhibitors of NF-κB and inhibitors of NF-κB kinase and facilitated NF-κB activity.

CONCLUSIONS

our data demonstrated that R-PC promoted activation and maturation of cultured dendritic cells and skewed the immunological function toward Th1 activity. Therefore, R-PC may have potential in regulating immune responses and application in reducing allergic asthma.

T-box 21 transcription factor is responsible for distorted T(H)2 differentiation in human peripheral CD4+ T cells

BACKGROUND

Regardless of T(H)1/T(H)2 theory, CD4(+) T cells of patients with allergic asthma, a typical T(H)2 disease, and those of healthy subjects expressed equivalent levels of IFN-gamma, even though T(H)2 cytokines were significantly upregulated in asthmatic patients.

OBJECTIVE

The mechanisms underlying distorted T(H)2 cell polarization in human T cells were elucidated.

METHODS

Cytokine-producing activity and the expression of T(H)1/T(H)2-specific transcription factors in naïve, T(H)1/T(H)2, or both CD4(+) T cells derived from human peripheral and cord blood were comparatively analyzed. The mechanisms of the differential expression of T-box 21 transcription factor (T-bet) in the cells were assessed by determining the chromatin accessibility at the TBX21 gene. The functional roles of T-bet and other transcription factors in human T(H)1/T(H)2 differentiation were further investigated.

RESULTS

T(H)2 cells derived from naive CD4(+) T cells in peripheral blood but not in cord blood produced IFN-gamma. T-bet was expressed in peripheral, but not cord blood, resting naive T cells. Consistently, the accessibility at the proximal TBX21 gene promoter in peripheral naive T cells was higher than that in cord blood naive T cells. IFN-gamma-producing activity was induced in T(H)2-differentiated cord blood T cells by means of ectopic expression of T-bet. In addition, a reduction of T-bet in peripheral T cells suppressed IFN-gamma production. T-bet not only upregulated IFN-gamma but also downregulated IL-4 and IL-13 gene transcription, independently of the modification of T(H)1/T(H)2 balance.

CONCLUSION

The expression of T-bet at a naive stage is crucial for the development of IFN-gamma-producing T cells in human peripheral blood, even in T(H)2-related diseases.

Autologous nucleus pulposus primes T cells to develop into interleukin-4-producing effector cells: an experimental study on the autoimmune properties of nucleus pulposus

An autoimmune response to herniated nucleus pulposus has been proposed to constitute a pathophysiologic mechanism for inducing sciatica based on the fact that nucleus pulposus under normal conditions is excluded from the development of immunological tolerance. The manifestation of an autoimmune response comprises different steps starting with antigen capture, continuing with activation of T helper (T(H)) cells and ending with production of autoantibodies. Activated T(H) cells differentiate into either T(H)1 cells, predominately producing proinflammatory cytokines such as interferon gamma (IFNgamma) or a T(H)2 subset mainly producing anti-inflammatory cytokines such as interleukin-4 (IL-4). The aim of the present study was to examine if exposure of autologous nucleus pulposus (NP) to the immune system for 3 weeks is potent enough to prime T(H) cells to differentiate into T(H)2 cells. The study was performed in a pig model allowing the exposure of NP to the immune system. To assess the polarization of T(H) cells the intracellular production of IFNgamma and IL-4 was measured in T cells by using flow cytometry. The revealed predominant production of IL-4 together with low production of IFNgamma in T cells after NP exposure to the immune system indicates that nucleus pulposus may prime T(H) cells to develop into IL-4-producing T(H)2 cells after being exposed to the immune system, for example, in association with disc herniation.

Effect of the glycemic control on intracellular cytokine production from peripheral blood mononuclear cells of type 1 and type 2 diabetic patients

AIMS

To evaluate the intracellular production of tumor necrosis factor (TNF-alpha), interleukine-6 (IL-6), INF-gamma, IL-8 and IL-10 in peripheral blood lymphomononuclear cells from type 1 and type 2 diabetic patients, stratified according to the glycemic control.

METHODS

Thirty-five diabetic patients (17 type 1 and 18 type 2) and nine healthy individuals paired to patients in terms of sex and age were studied. Nine patients of each group were on inadequate glycemic controls. Intracellular cytokines were evaluated using flow cytometry. Cell cultures were stimulated with LPS to evaluate TNF-alpha and IL-6 or with PMA and Ionomycin to evaluate IFN-gamma, IL-8 and IL-10 intracellular staining.

RESULTS

The percentages of CD33(+) cells bearing TNF-alpha and CD3(+) cells bearing IL-10 were increased in type 1 diabetic patients with inadequate glycemic control in relation to those with adequate control. In contrast, the percentage of CD3(+) cells bearing IL-8 was decreased in type 2 patients under inadequate glycemic control.

CONCLUSIONS

The glycemic control is important for the detection of intracellular cytokines, and may contribute towards the susceptibility to infections in diabetic patients.

Induction of IL-10 producing CD4+ T cells with regulatory activities by stimulation with IL-10 gene-modified bone marrow derived dendritic cells

Dendritic cells (DCs) can induce both tolergenic as well as effective immune responses in the lung. Pulmonary DCs producing interleukin (IL)-10 mediated tolerance induced by respiratory exposure to antigen. IL-10 is an important immunosuppressive cytokine, which inhibits maturation and function of DC. To assess whether IL-10 producing DCs can exert the tolergenic effect through the differentiation of regulatory T cells, bone marrow derived DCs were genetically modified by IL-10 expressing adenovirus. IL-10 gene modified DCs (Ad-IL-10-DC) displayed a characteristic phenotype of immature DCs. Here we showed that in vitro repetitive stimulation of naïve DO11.10 CD4(+) T cells with Ad-IL-10-DCs resulted in a development of IL-10 producing T-cell regulatory cells. These T cells could not proliferate well but also lost their ability to produce interferon-gamma upon restimulation with irradiated splenocytes and ovalbumin peptide. Furthermore, in co-culture experiments these T cells inhibited the antigen-driven proliferation of naïve CD4+ T cells in a dose-dependent manner. Our findings demonstrated that IL-10 producing DCs had the potential to induce the differentiation of Tr1-like cells and suggested their therapeutic use.

Analysis of Th1/Th2 T-cell subsets

Specific immune responses are mediated by activated CD4+ T-helper (Th) cells. Two major subsets, denoted Th1 and Th2, have been identified that are characterized by their distinctive cytokine secretion pattern and associated effector functions. The signature cytokines of Th1 and Th2 cells are interferon-gamma and interleukin-4, respectively. Because of the dominant role of Th cells in directing specific immunity, the analysis of Th subsets by means of determining their signature cytokines has contributed greatly to the progress that has been made in recent years in the understanding of protective as well as pathogenic immune responses. Several methods, such as reverse transcriptase polymerase chain reaction, enzyme-linked immunosorbent assay, ELISpot, and intracellular flow cytometric analysis are used for the analysis of T-cell cytokines and, thus, of Th subsets. Here, we briefly discuss the advantages and disadvantages of these methods and describe in detail a standard protocol for the analysis of human Th subsets by means of detection of cytoplasmic cytokines by flow cytometry.

Type 1 and 2 T helper cell-mediated colitis

PURPOSE OF REVIEW

Abrogation of mucosal T cell homeostasis by exaggerated not only T helper 1, but also T helper 2 cells is a major problem that leads to intestinal inflammation. In this regard, it is important to understand these different aspects of mucosal inflammation.

RECENT FINDINGS

Both T helper 1 and 2 cells play central roles in the induction of mucosal immune responses including secretory IgA antibody production, which would be the most beneficial aspect for the host defense mechanism. T helper 1- and 2-type responses, however, exhibit other roles in the abrogation of intestinal homeostasis. Although it has been shown that T helper 1-type immune responses are key players in the induction of intestinal inflammation in mice colitis models and also in inflammatory bowel diseases in humans, studies in murine colitis models clearly show that T helper 2-type responses are also involved in the pathophysiology of the intestinal inflammation. Both regulatory type T cells and T helper 17 cells are involved to down- or upregulate aberrant T helper 1 and 2 cell responses.

SUMMARY

Understanding the cellular and molecular mechanisms of crosstalk among T helper 1, 2, 17 and T regulatory 1 cells is central for the prevention or treatment of inflammatory bowel diseases.

Inhibitory effect of pooled human immunoglobulin on cytokine production in peripheral blood mononuclear cells

Human intravenous immunoglobulins (IVIG) are widely used as immunomodulators because of their ability to modify the course of various immune-mediated diseases. We investigated the mechanisms responsible for the regulatory effects of IVIG on in vitro human peripheral blood mononuclear cell (PBMC) cytokine production. Pre-incubation of PBMCs with IVIG inhibited lipopolysaccharide (LPS) and phorbol 12-myristate 13-acetate (PMA)/ionomycin stimulated cytokine secretion. Pre-incubation of PBMCs with IVIG induced a significant inhibition of LPS-stimulated (IL-6) secretion (p = 0.045); the effect on tumor necrosis factor-alpha (TNF-alpha) secretion was not significant (p = 0.234). Pre-incubation of PBMCs with IVIG inhibited IL-6 secretion (p = 0.033) stimulated with anti-CD14 antibody cross-linking but had no significant effect on TNF-alpha secretion (p = 0.125). PBMC pre-incubation with anti-CD14-blocking antibody induced a significant reduction (p = 0.042) in LPS-stimulated TNF-alpha secretion in comparison with a non-significant reduction (p =0.256) noted with IVIG pre-treatment. In contrast, pre-incubation of PBMCs with anti-CD14 antibody did not induce a significant reduction in LPS-stimulated IL-6 secretion (p = 0.166) in comparison with a significant reduction (p = 0.001) induced with IVIG pre-treatment. Our data suggest that the immunoregulatory properties of IVIG may rely on several mechanisms, some of which may be independent of CD14. Our data also showed that cross-linking cell membrane-bound IVIG with anti-human kappa- and lambda-chain antibodies resulted in cytokine secretion levels similar to those elicited by LPS. In addition, intracellular DNA staining results did not support the involvement of apoptosis in the regulatory mechanisms of IVIG. This data may further our understanding of the immunoregulatory effects exerted by IVIG on the production of inflammatory-response mediators.

Fluorescent-activated cell-sorting analysis of intracellular interferon-γ and interleukin-4 in fresh and frozen human peripheral blood T-helper cells

T-helper (Th) cells can be classified into at least three subsets based on their cytokine profiles: Th0, Th1, and Th2. The functional significance of each subset of Th cells can be determined in isolated human peripheral blood mononuclear cells (PBMC). Using two- or three-color cytometric detection of intracellular cytokines. These analyses have been limited by the requirement for fresh cells making sequential samples and longitudinal studies difficult. Cryopreservation of PBMC in liquid nitrogen for up to 1 year was evaluated to determine whether the Th1/Th2 ratio remained unchanged in cryopreserved lymphocytes. Aliquots of human PBMC from normal volunteers analyzed for activation using phorbol myristate acetate and evaluated using morphology showed that the surface marker expression was unchanged in fresh and frozen cells. Cytokine expression was measured using intracellular cytokine staining and three-color flow cytometric analysis. The percentages of cells producing interferon (IFN)-gamma or interleukin (IL)-4 were determined after 16 hours of phorbol myristate acetate and ionomycin stimulation in the presence of brefeldin A. No significant difference was found in cytokine production between fresh and frozen cells. The percentage of IFN-gamma and IL-4 producing CD3-positive fresh T cells was 19.2+/-5.8 percent and 0.9+/-0.4 percent vs. 17.6+/-0.75 percent and 0.9+/-0.3 percent, respectively, for frozen PBMC. The effects of thermal injury on the Th1/Th2 cytokine ratio and the development of hypertrophic scarring were then determined. Twelve burn patients examined 4 weeks postburn showed a significant shift in the Th1/Th2 ratio, compared with 13 normal human volunteers used as controls. IL-4 levels in the patient group were significantly higher than controls at 1 month postburn (12.7+/-2.6 percent vs. 3.9+/-0.5 percent, p<0.01) and IFN-gamma levels were significantly lower (9.3+/-1.7 percent vs. 15.3+/-2.3 percent, p<0.05). Thus, PBMC can be cryopreserved for up to 1 year, enabling investigation of chronologic changes in Th1/Th2 profiles. It is suggested that a "locked on" Th2 profile may contribute to the development of hypertrophic scarring after burn injury.

Inhibitory activity of 1,8-cineol (eucalyptol) on cytokine production in cultured human lymphocytes and monocytes

BACKGROUND

The therapeutic value of secretolytic agents in COPD and asthma is still disputed. For this reason, in a preclinical study we aimed to test the potential anti-inflammatory efficacy of 1,8-cineol (eucalyptol) in inhibiting polyclonal stimulated cytokine production by human unselected lymphocytes and LPS-stimulated monocytes.

METHODS

Cytokine production was determined following 20 h of incubation cells with 1,8-cineol simultaneously with the stimuli in culture supernatants by enzyme immunoassay.

RESULTS

Therapeutic concentrations of 1,8-cineol (1.5 microg/ml=10(-5)M) inhibited significantly (n=13-19, p=0.0001) cytokine production in lymphocytes of TNF-alpha > IL-1beta> IL-4> IL-5 by 92, 84, 70, and 65%, respectively. Cytokine production in monocytes of TNF-alpha > IL-1beta> IL-6> IL-8 was also significantly (n=7-16, p<0.001) inhibited by 99, 84, 76, and 65%, respectively. In the presence of 1,8-cineol (0.15 microg/ml=10(-6)M) production of TNF-alpha>IL-1beta by monocytes and of IL-1beta> TNF-alpha by lymph-ocytes was significantly inhibited by 77, 61 and by 36, 16%, respectively. 1,8-cineol (10(-6)M) had a larger impact on TNF-alpha and IL-1beta-production in monocytes compared to lymphocytes (p<0.03) and similar effects (p>0.59) at therapeutically relevant concentrations of 1,8-Cineol (10(-5)M).

CONCLUSION

These results characterize 1,8-cineol as strong inhibitor of TNF-alpha and IL-1beta and suggest smaller effects on chemotactic cytokines. This is increasing evidence for the role of 1,8-cineol to control airway mucus hypersecretion by cytokine inhibition, suggesting long-term treatment to reduce exacerbations in asthma, sinusitis and COPD.

Predominance of type 1 (Th1) cytokine production in the liver of patients with HCV-associated mixed cryoglobulinemia vasculitis

BACKGROUND/AIMS

Patients with hepatitis C virus (HCV) mixed cryoglobulinemia (MC) vasculitis have a higher mortality rate and more frequent incidence of cirrhosis than their cryoglobulin-negative counterparts. To compare the cytokine profile of liver-infiltrating T cells in HCV-infected patients with or without MC vasculitis.

METHODS

Hepatic biopsy specimens were obtained from HCV infected patients with and without MC vasculitis. Using intracellular staining and flow cytometry, we assessed the ability of freshly isolated liver T cells from these biopsies to produce IFN-gamma, TNF-alpha, IL-2, IL-4, and IL-10 in response to stimulation with PMA and ionomycin.

RESULTS

HCV-MC vasculitis patients compared to HCV-MC negative controls have an enhanced hepatic T cells production of Th1-type cytokines [i.e. TNF-alpha(30.3 +/- 13% vs. 15.5 +/- 5%, P = 0.01), IL-2 (20.2 +/- 9% vs. 10 +/- 4%, P = 0.01) and IFN-gamma (22.2 +/- 11% vs. 9.4 +/- 4%, P = 0.008)], whereas IL-10, a representative Th2-type cytokine, was significantly lower (7.2 +/- 4% vs. 17 +/- 7%, P = 0.01).

CONCLUSIONS

T cell from the liver of HCV-MC vasculitis patients display a significantly augmented liver Th1 profile compared to MC-negative controls. This enhanced production of type-1 cytokines may account for a more severe course of liver disease.

In Vitro Immunomodulatory Activity of Bo‐Yang‐Hwan‐O‐Tang

Bo-yang-hwan-o-tang (BHT), an herbal decoction has been mainly used for improvement of blood flow in oriental medicine. Its in vivo immunomodulation was recently demonstrated but the effective mechanisms have not been described. This study was carried out to evaluate in vitro immunomodulatory activity of BHT. Water extract of BHT significantly promoted in vitro proliferative responses of mouse spleen cells (SPC) and also further enhanced the proliferation of SPC stimulated with anti-CD3 antibody. Unexpectedly, addition of BHT extract did not affect proliferation of both resting and CD3-activated T cells, whereas it showed a strong mitogenic activity on B cells. Flow cytometric analysis of CFSE-stained SPC showed that BHT-mediated enhancement of CD3-activated SPC proliferation is due to T cell, but not B cell, division. Mixed culture experiment combining T and mitomycin C-treated B cells demonstrated that BHT-mediated enhancement of CD3-activated T cell proliferation was dependent on the presence of B cells. However, B cell-derived factors were not involved in BHT effect on T cell proliferation. In the presence of B cells, BHT treatment resulted in a great enhancement in IL-2 production of CD3-activated T cells, and BHT effect on T cell proliferation was completely abrogated by addition of exogenous IL-2, indicating that IL-2 plays a critical role in BHT-mediated enhancement of CD3-activated T cell proliferation. Taken together, our data revealed that BHT possesses a potent B cell mitogenic activity and also can enhance activated T cell response through B cell regulation.

Umbilical cord blood–naive T cells but not adult blood–naive T cells require HLA class II on antigen-presenting cells for allo-immune activation

Because a relatively low incidence and severity of graft-versus-host disease after umbilical cord blood (UCB) transplantation is observed, we investigated whether T cells from UCB or adult blood (AB) were differentially activated by antigen-presenting cells with or without human leukocyte antigen (HLA)-DR expression. T cells from UCB or AB, or CD45RA(+) naive T cells and CD45RO(+) memory T cells separated from AB, were stimulated with the HLA-DR(+) or HLA-DR(-) cell line AML193. On days 1-3 after stimulation, numbers of interleukin (IL)-2, IL-4, IL-10 or interferon gamma (IFN-gamma)-secreting cells were determined by enzyme-linked immunospot analysis. No IL-4 or IL-10 was produced. AML193-DR(+) cells induced IL-2 and IFN-gamma secretion with slower kinetics and lower levels in UCB T cells than in AB T cells. AML193-DR(+) cells induced comparable IL-2 but higher IFN-gamma secretion in CD45RA(+) T cells from AB than in UCB T cells. AML193-DR(-) cells did not induce IL-2- or IFN-gamma secretion in UCB T cells, but stimulated both CD45RA(+) and CD45RO(+) T cells from AB to secrete IL-2 and IFN-gamma. Thus, not only the absence of memory T cells but also the inability to respond to HLA-DR-negative antigen-presenting cells and the slower kinetics and level of activation found for naive T cells from UCB as compared with AB may partly explain the reduced antirecipient reactivity after UCB transplantation.

Both allergen-specific CD4 and CD8 Type 2 T cells decreased in asthmatic children with immunotherapy

Allergen-specific immunotherapy (IT) has been used for the treatment of atopic diseases since the turn of this century. The precise working mechanisms, however, remain to be clarified. The aim of this study was to investigate the role of particular subsets of allergen-specific T cells in the non-atopic individuals, untreated asthmatic children and the asthmatic children receiving immunotherapy. We collected peripheral blood from 16 untreated asthmatic children and 17 asthmatic children receiving immunotherapy over one and half years. All the patients were sensitive to mite allergen. Peripheral blood mononuclear cells (PBMC) were isolated and, in vitro, stimulated with crude mite extract to enrich the mite-specific T-cell population. After 14 days, the enriched mite-specific T cells were stimulated with phorbol-12-myristate-13-acetate (PMA) and ionomycin for intracellular detection of cytokines such as IFN-gamma, IL-4 in CD4+ and CD8+ T lymphocytes. The data here demonstrated that the levels of mite-specific IgG4 and IgA increased significantly in asthmatic children after immunotherapy. In addition, both IL-4 expressing CD4+ and CD8+ T cells were significantly lower in asthmatic children after immunotherapy compared with those of before treatment and the normal control (p < 0.05). In contrast, the frequency of IFN-gamma expressing CD4+ and CD8+ T cells did not significantly differ between untreated and SIT-treated groups. All these data suggested that decreased Type 2 CD4+ and CD8+ T cells might be closely correlated with the regulatory mechanisms of immunotherapy.

Discrete and complementary mechanisms of protection of beta-cells against cytokine-induced and oxidative damage achieved by bcl-2 overexpression and a cytokine selection strategy

We have been investigating the potential utility of engineered cell lines as surrogates for primary islet cells in treatment of type 1 diabetes. To this end, two strategies that have emerged for procuring cell lines with resistance to immune-mediated damage are 1) selection of cytokine-resistant cell lines by growth of INS-1 insulinoma cells in iteratively increasing concentrations of interleukin (IL)-1beta + gamma-interferon (IFN-gamma), and 2) stable overexpression of the anti-apoptotic gene bcl-2 in INS-1 cells. Herein, we show that bcl-2-overexpressing cells are resistant to the cytotoxic effects of reactive oxygen and nitrogen species (ROS/RNS), but are only modestly protected against high concentrations of IL-1beta + INF-gamma, whereas the converse is true in cytokine selected cells. We also found that the combination of bcl-2 expression and cytokine selection confers a broader spectrum of resistance than either procedure alone, such that the resultant cells are highly resistant to cytokines and ROS/RNS, with no impairment in glucose-stimulated insulin secretion. INS-1-derived cells with combined bcl-2 expression and cytokine selection are also more resistant to damage induced by coculture with mitogen-activated peripheral blood mononuclear cells. Surprisingly, application of the cytokine selection procedure to bcl-2-overexpressing cells does not result in impairment of nuclear factor-kappaB translocation, iNOS expression, and NO production, as clearly occurs upon application of the selection procedure to cells without bcl-2 overexpression. Further investigation of the diverse pathways involved in the development of cytokine and ROS/RNS resistance may define simplified and specific strategies for preservation of beta-cell mass.

Anti-inflammatory effects of leflunomide on cultured synovial macrophages from patients with rheumatoid arthritis

BACKGROUND

Leflunomide and its active metabolite A77 1726 reversibly inhibits the enzyme dihydro-orotate dehydrogenase, the rate limiting step in de novo synthesis of pyrimidines and progression of the cell cycle in different cell lines, mainly activated T lymphocytes.

OBJECTIVE

To analyse in vitro the possible anti-inflammatory effects exerted by A77 1726, on cultured macrophages, obtained from the synovial tissues of patients with rheumatoid arthritis (RA).

METHODS

The effects of different doses of A77 1726 on intracytoplasmic expression and extracellular concentration of inflammatory cytokines (tumour necrosis factor alpha (TNFalpha), interleukin (IL) 1beta, IL6), as well as the influence on production and expression of intercellular adhesion molecule-1 (ICAM-1) and cyclo-oxygenase 2 (COX-2) by primary cultures of synovial macrophages from patients with RA, were evaluated by immunocytochemistry and western blot analysis. The observations were made at four and 24 hours.

RESULTS

A progressive and significant time and dose dependent decrease of the number of positive macrophages for intracellular TNFalpha and IL1beta, treated with different doses of A77 1726, was found in comparison with untreated cells. The extracellular concentration of TNFalpha was found to be significantly decreased in media containing cultured macrophages at 24 hours for all tested doses of A77 1726. At 24 hours, a significant time and dose dependent decrease of ICAM-1 and COX-2 expression by cultured macrophages after A77 1726 treatment was found.

CONCLUSIONS

In conclusion, the mechanism of antiproliferative activity exerted by leflunomide on activated T lymphocytes seems to be the same mechanism (alteration of the cell cycle progression) which interferes with the functions of other activated cells-namely, the monocytes/macrophages, which are strongly involved in the inflammatory reaction in RA synovial tissue. The positive clinical results seem to confirm that leflunomide exerts an anti-inflammatory action on phagocytic cells in short and long term treatment of RA.

Activated umbilical cord blood cells from pre-term and term neonates express CD69 and synthesize IL-2 but are unable to produce IFN-gamma

BACKGROUND

The immune response exhibits quantitative and qualitative differences throughout human development. Both phenotypical and functional immaturity of newborn immune cellular components have been reported. We aimed to analyze possible differences in cellular activation assessed by expression of surface CD69 and cytokine production in mononuclear peripheral blood cells from premature (<37) and term (>37 weeks of gestation) neonates compared to adult donors.

METHODS

Ten persons from each group were selected; none was infected, immunodepressed, under medical treatment, or had any congenital abnormalities. Blood was obtained from umbilical cord of term and pre-term donors and vein punction of adults. All samples were collected in heparin and subsequently activated with PHA-L or PMA plus ionomycin at 37 degrees C for 4 h. After incubation, cells were labeled to determine CD69 expression on CD3+CD4+, CD3+CD8+, CD19+, and CD16+56+ subpopulations. Intracellular staining was performed to analyze IFN-gamma, IL-2, and CD69 in CD3+ cells. After staining, cells were analyzed by flow cytometry.

RESULTS

We first found a substantially higher number of CD3+CD4+CD69+ cells in premature and term neonates than in adults. Secondly, percentage of CD3+CD8+, CD56+, and CD19+ cells expressing CD69 was similar among the three groups. Thirdly, expression of CD69 was higher in CD19+ cells than in CD16+56+ cells of all three groups. Regarding cytokine production, IFN-gamma was detected only in cells from adults and was consistent in all individuals analyzed. In sharp contrast, IL-2 and intracellular CD69 (iCD69) were detected in all three groups, with no significant differences among them. Induction of IL-2 and iCD69 showed that lack of response with IFN-gamma was restricted to pre-term and newborn populations.

CONCLUSIONS

In summary, our results showed that a) CD69 is an early activation marker of both mononuclear umbilical cord and peripheral blood cells activated by a mitogenic stimulus, and b) newborn CD3+ cells probably lack conditions required to progress through the activation process that leads to IFN-gamma production. These conditions are still unknown but certainly constitute an interesting issue for further studies.

TCR usage and cytokine expression in peripheral blood and BAL T cells

T cells are thought to play an important regulatory role in atopic asthma. We hypothesized that human blood and BAL T cell subsets bearing various TCR-Vbeta genes might show selective differences in their cytokine profile. Peripheral blood (PB) and bronchoalveolar lavage (BAL) T cells from seven atopic asthmatic and six non-atopic non-asthmatic subjects were stimulated with PMA and ionomycin in the presence of monensin and analysed for TCR-Vbeta expression and production of cytokines at the single cell level. The percentage of IFN-gamma- and IL-2-producing BAL T cells was elevated compared with PB T cells from both the asthmatic subjects and the non-atopic, non-asthmatic controls. A small percentage of PB and BAL T cells produced IL-4 and IL-5, in asthmatic and normal subjects. In peripheral blood, the percentage of T cells expressing each cytokine was similar in the various TCR-Vbeta subsets and in total CD3+ T cells in all normal and six of seven asthmatic subjects. However, there was a substantial degree of heterogeneity in the cytokine profile of BAL TCR-Vbeta subsets compared with the total CD3+ T cells. This was more obvious in the asthmatic subjects with a reduction in the percentage of IFN-gamma- and IL-2-expressing T cells (five of seven asthmatic subjects) and an increase in the percentage of IL-4- and IL-5-expressing T cells (two of seven asthmatic subjects). These data confirm previous findings of an elevated proportion of IFN-gamma- and IL-2-producing BAL T cells while only a small proportion of PB and BAL T cells produce IL-4 and IL-5. Moreover, subsets of BAL T cells, defined by their TCR-Vbeta usage, may differ in their cytokine profile compared with the total CD3+ T cells, implying that T cells expressing different Vbeta elements may play different roles in regulating the airway inflammation in asthma.

Peripheral blood T lymphocytes from systemic sclerosis patients show both Th1 and Th2 activation

Our objective was to investigate the phenotype of helper T cells in the peripheral blood of patients with systemic sclerosis (SSc). PBMC from 15 patients with SSc and 15 sex- and age-matched controls were investigated for lymphocyte subpopulations (CD3, CD4, CD8, CD19, CD16/CD56, CD3-DR); IL-2, IL-4, and IFN-gamma mRNAs; and the relative cytokines in their cytoplasm. The last assay was carried out both in unstimulated and in PMA-activated PBMC. SSc patients presented a higher percentage of activated T cells, CD3+ DR+ (19.7 +/- 9.9 vs 5.1 +/- 2.5%; P < 0.0001); 12 of them presented IFN-gamma mRNA-positive cells; and none IL-2 or IL-4 mRNAs. Under basal conditions, PBMC from six SSc patients contained IL-2, IL-4, and IFN-gamma (i.e., they showed both Th1 and Th2 activation), and 1 IFN-gamma only. PMA-stimulated PBMC of patients differed from those of controls only in the increased percentage of IFN-gamma positive cells (52 +/- 12 vs 37 +/- 11%; P < 0.01). Our study demonstrates that Thl activation occurs in the peripheral blood of SSc patients. This evidence must be faced with from both a pathogenetic and a therapeutical point of view.

Intracellular cytokine profile of cord and adult blood monocytes

Cord blood (CB) transplantations are associated with low graft-versus-host disease (GVHD). The pathophysiology of GVHD involves interaction and activation of different cell types, as lymphocytes and monocytes, and results in a cascade of cytokine production. After antigen or mitogen stimulation, CB monocytes release lower levels of cytokines than adult blood (AB) monocytes. In this study, the detection of intracellular IL-1 beta and TNF-alpha produced by monocytes was evaluated in response to tuberculin PPD to investigate whether the reduced capacity of CB monocytes to secrete cytokines could be related to an impaired functional activity and to a particular phenotypic profile. Results showed that the percentage of CD64(+)monocytes producing intracellular IL-1 beta and TNF-alpha was significantly lower in CB and that the phenotypic profile of CB monocytes producing these cytokine (CD64(+)CD14(+)) was different to that of AB monocytes (CD64(+)CD14(+), CD64(+)CD33(+) and CD64(+) CD45RO(+)). These results suggest that the lower capacity of CB monocyte populations to produce IL-1 beta and TNF-alpha might be due to a functional immaturity of CB monocytes at the cellular level as reflected by the different phenotypic profile of CB monocytes.

T cell phenotypes of the normal nasal mucosa: induction of Th2 cytokines and CCR3 expression by IL-4

Mucosal environments such as that of the nose are points of first contact between the human organism and its environment. At these sites the immune system must be regulated to differentiate between and respond appropriately to pathogens and harmless contaminants. T cell-driven immune responses broadly fall into Th1- or Th2-type phenotypes, with increasing evidence that the recruitment of these T lymphocyte subsets is mediated by selective expression of specific chemokine receptors. We have investigated the immunology of the normal nasal mucosa. We show that nasal T cell lines from normal individuals, expanded by culture in IL-2, show reduced expression of the Th2-type cytokines IL-4 and IL-5 compared with lines derived from the blood of the same subjects. These T cells also show reduced expression of the Th2-selective chemokine receptor, CCR3, but similar levels of CCR4 compared with the blood-derived lines. This apparent suppression of Th2 cytokine and CCR3 expression by nasal T cells was reversed by addition of IL-4 to the culture medium. These data are consistent with the presence of a nasal mucosal microenvironment that suppresses Th2 responses and may represent a protective measure against atopic allergic disease in humans and a favoring of Th1 responses to infectious agents. In contrast, T cell expression of CCR1 was higher in the nose than in the blood regardless of the culture medium cytokine environment in keeping with a role for this receptor in tissue homing or lymphocyte activation.

TH1/TH2 and TC1/TC2 profiles in peripheral blood and bronchoalveolar lavage fluid cells in pulmonary sarcoidosis

BACKGROUND

Sarcoidosis is thought to be a type-1 cytokine-mediated disorder. However, few data are available on the profiles of cytokine expression by TH cells at the single-cell level, as assessed by intracellular cytokine flow cytometry. Additionally, it remains to be determined whether the balance of TC1 and TC2 cells can be altered in sarcoidosis.

OBJECTIVE

The aim of this study was to evaluate the TH1/TH2 and TC1/TC2 balances in sarcoidosis.

METHODS

Using triple-color flow cytometry and phorbol 12-myristate acetate/ionomycin stimulation, we measured the production of the intracellular cytokines IFN-gamma and IL-4 in CD4+ and CD8+ T cells separately, which were obtained from peripheral blood and bronchoalveolar lavage fluid (BALF) of 20 patients with sarcoidosis, and compared their cytokine expressions with those of 10 normal subjects.

RESULTS

Under unstimulated conditions, there were no significant differences in the proportion of cytokine-producing CD4+ or CD8+ T cells in peripheral blood or BALF between patients with sarcoidosis and normal control subjects. On stimulation with phorbol 12-myristate acetate/ionomycin for 4 hours, in BALF of the patients, but not in peripheral blood, we found a significant increase in the percentage of IFN-gamma-producing CD4+ T cells and a decrease in the percentage of IL-4-producing CD4+ T cells, resulting in a 3.5-fold higher ratio of IFN-gamma/IL-4-producing CD4+ T cells compared with that found in normal subjects. In contrast, no difference was found in the proportions of cytokine-producing CD8+ T cells or the ratio of IFN-gamma/IL-4-producing CD8+ T cells in either the peripheral blood or BALF between the patients and normal subjects.

CONCLUSIONS

These findings suggest that the prominent shift toward a type-1 phenotype may occur in CD4+ T-cell populations but not in CD8+ T-cell populations in the affected organs of sarcoidosis.

Analysis of the antigen-specific T cell response in reactive arthritis by flow cytometry

OBJECTIVE

In reactive arthritis (ReA) a bacteria-specific T cell response to the triggering microbe is detected in synovial fluid (SF), and an impaired Th1 cytokine response has been described. The recent identification of immunodominant bacterial proteins/peptides and new technologies make a more detailed analysis of the immune response possible. The aim of the present study was to use these new techniques to determine the antigen-specific T cell frequency and the cytokine secretion pattern on stimulation with bacteria-derived recombinant proteins in the peripheral blood (PB) and SF from patients with ReA.

METHODS

In 3 patients with Chlamydia-induced ReA and 2 patients with Yersinia-induced ReA, the SF T cell response was investigated after stimulation with the Chlamydia-derived proteins major outer membrane protein (MOMP) and heat-shock protein 60 (Hsp60) and the Yersinia-derived proteins 19-kd protein and Hsp60. In 3 of these patients, the PB T cell response was investigated in parallel. T cells were stimulated in whole blood or whole SF with antigen plus anti-CD28 for 6 hours, brefeldin A was added after 2 hours, and cells were fixed and stained with antibodies against the surface markers CD4 and CD69 and against the cytokines interferon-gamma (IFNgamma), tumor necrosis factor alpha, interleukin-10 (IL-10), and IL-4. Positive cells were quantified by flow cytometry.

RESULTS

In the 3 patients with Chlamydia-induced ReA, the antigen-specific T cell frequency (percentage of IFNgamma CD69 double-positive CD4+ T cells) in response to MOMP (mean +/- SD 1.2 +/- 1.38%) and to Hsp60 (1.21 +/- 1.45%) in SF was about the same. In the 2 patients with Yersinia-induced ReA, the mean +/- SD frequency was 0.66 +/- 0.36% in response to the Hsp60 and 03% +/- 0.22 in response to the 19-kd protein. In the 3 patients whose PB was evaluated, the corresponding T cell response was > or =10 times lower. In 2 patients with Chlamydia-induced ReA, antigen-specific IL-10-positive CD4+ T cells were detected in 0.10-0.23% of the CD4+ T cell subpopulation.

CONCLUSION

The frequency of antigen-specific T cells to Chlamydia- and Yersinia-derived antigens in the SF of ReA patients is between 1:200 and 1:50. Both the chlamydial Hsp60 and MOMP are dominant T cell antigens in Chlamydia-induced ReA. In patients with Chlamydia-induced ReA, we detected antigen-specific IL-10 secretion, which might mediate an inhibition of effective bacterial clearance.

Naive T cells from cord blood have the capacity to make Types 1 and 2 cytokines

We wanted to determine whether naive T cells could make the Types 1, 2 and 0 defining cytokines Interleukin (IL)-4 and Interferon (IFN)gamma. We show that stimulation of naive T cells (CD3+ CD45RA+) derived from cord blood by phorbol ester (phorbol-12-myristate-13-acetate: PMA) plus lonomycin induced detection of Types 1, 2 and 0 cells. Conversely, when we stimulated the naive T cells through the T cell receptor (with anti-CD3 monoclonal antibody alone) there was no detection of IFNgamma or IL-4 producing cells. Stimulation with PMA and CD3 induced detection of only Type 2 cells. This unexpected finding shows that there is a high frequency of Type 2 cells within the naive T cell population, contrary to previously published reports. The highest percentage of Type 2 naive cells (10.5%) was obtained with 50 ng/ml PMA plus 50 microg/ml anti-CD3. Thus, we have shown that naive T cells derived from cord blood have the capacity to make both Types 1 and 2 cytokines and the frequency of cells producing these cytokines can be greater than 20%, depending on the stimulus used.

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.

Cytokine and cytokine receptor expression as a biological indicator of immune activation: important considerations in the development of in vitro model systems

Studies of the biological activity of T-lymphocytes in response to immune activation are often based on in vitro models using polyclonal activators such as anti-CD3 antibodies, pharmacological agents, like phorbol esters, and mitogens, like phytohemagglutinin. Activation of T-lymphocytes results in expression of cytokine receptors, production and secretion of cytokines, expression of cell surface activation markers, and cellular proliferation. This study reviews the most commonly used methods of in vitro activation by non-specific polyclonal activators on target populations of both isolated T-lymphocytes and mononuclear cells. The resultant biological activity was measured by expression of cell surface cytokine receptors, intracellular cytokine expression and quantitation of secreted cytokines. This study demonstrates the different results that can occur depending upon the nature of the population making up the responding cells, method of activation, and duration of culture. Special care must be taken when developing in vitro models of immune activation and interpreting the resultant biological activity. The results of the experiments reviewed here demonstrate the importance of measuring cytokine receptors and quantitating cytokine secretion in conjunction with identifying the cytokine-producing cells. Recent advances in flow cytometry technology permit analysis of all these parameters on a single platform.

Can cord blood cells support the cytokine storm in GvHD?

Cord blood has a high number of proliferating hematopoietic progenitors and is therefore used as an alternative source of hematopoietic cells for allogeneic transplantation. In addition there is a wider availability of cord blood and a lower cost of procurement compared to bone marrow. However one of the most interesting immunological benefits of a cord blood transplant that has been proposed is the low severity of Graft versus Host Disease (GvHD). This review aims to address some of the immunological reasons why this may be the case by assessing the role of cord blood cytokines in the cytokine storm of GvHD.

Weaning induces an increase in the number of specific cytokine-secreting intestinal lymphocytes in mice

Intestinal immunity differs from systemic immunity in several aspects and is frequently studied separately. In this work we have analysed the frequency of mononuclear cells spontaneously secreting the cytokines IL-2, IL-4, IL-5, IL-6, IL-10, interferon gamma (IFN-gamma) and tumour necrosis factor (TNF-alpha), in Peyer's patches and lamina propria of small intestine in mice by enzyme linked immunosorbent spot (ELISPOT) during 1 month after weaning. We have found a high percentage of spontaneous Th(1)as well as Th(2)cytokine-secreting lymphocytes in both populations, Peyer's patches and lamina propria. An increase in the number of the lymphocytes secreting most of the studied cytokines, at 1 and 2 weeks after weaning, was also observed. These results suggest that the increase in the number of cytokine secreting lymphocytes may be one of the potential mechanisms involved in the development of the intestinal immune system at weaning.

Inhibitory activity of fenoterol on Dermatophagoides-, Parietaria-, tetanus-toxoid-, and Candida albicans-stimulated blood mononuclear cells: differences in beta2-adrenoreceptor stimulation but not in cell apoptosis

beta2-adrenoreceptor agonists have the ability to downregulate in vitro the proliferative response of peripheral blood mononuclear cells (BMCs). This activity could be related to a variety of beta2-adrenoreceptor-mediated functions, including induction of cell apoptosis in activated T-cells. To test this hypothesis, BMCs from atopic subjects, sensitized to house dust mites (Dermatophagoides [Der p]) and/or to Parietaria were incubated with fenoterol (10(-8)-10(-5) M) in the presence of (a) purified allergen extracts (Der p [5 microg/mL] or Parietaria [5 microg/mL]) or (b) antigens (tetanus toxoid [1 microg/mL] or Candida albicans [5 x 10(5) bodies/mL]). The BMC proliferation was assessed by [3H] thymidine incorporation and cell apoptosis was assessed by evaluating DNA fragmentation by a fluorescence technique, using propidium iodide. In cultures stimulated with Der p or with Parietaria, fenoterol induced a dose-dependent inhibition of BMC proliferation, significant also at the lowest concentration tested (10(-8) M) (p < 0.05, each comparison). In contrast, the inhibitory activity of the drug on tetanus-toxoid-stimulated BMCs was significant only at the highest dose tested (10(-5)M) (p < 0.05), whereas no effect was seen when BMCs were stimulated with C. albicans extract (p > 0.05). The different inhibitory efficacy of fenoterol appeared to be related to the degree of activation of beta2-adrenoreceptors on the different BMC populations that responded to the different stimuli. Indeed, in the presence of fenoterol (10(-6) and 10(-5)M), a significant increase in cyclic adenosine monophosphate (cAMP) levels was seen in Der p- or Parietaria-stimulated cells (p < 0.05; each comparison), but not in cell cultures stimulated with tetanus toxoid or with C. albicans extracts (p > 0.05; each comparison). Finally, the percentage of cells with fragmented DNA was lower in cultures stimulated with Der p or Parietaria than in those stimulated with tetanus toxoid or C. albicans, and the presence of fenoterol did not modify cell apoptosis (p > 0.05; each comparison). Thus, the different inhibitory activity of fenoterol on BMCs activated by allergens (Der p or Parietaria) or by antigens (tetanus toxoid or C. albicans) seems to be related to differences in beta2-adrenoreceptor expression and/or function in the different antigen-specific T-cell subsets, but it is not influenced by changes in cell apoptosis.

Identification of rat IL-1beta, IL-2, IFN-gamma and TNF-alpha in activated splenocytes by intracellular immunostaining

We have developed a sensitive three-step indirect immunofluorescence method to identify individual rat cells that produce cytokines including IL-1beta, IL-2, IFN-gamma and TNF-alpha. Cultured rat splenocytes were polyclonally activated to cytokine synthesis by mitogens such as lipopolysaccharide or a combination of a protein kinase C activator (phorbol 12-myristate 13-acetate) and a calcium ionophore (ionomycin). Careful selection of either antigen affinity-purified polyclonal or monoclonal cytokine-detecting antibodies combined with gentle fixation and permeabilization of the cells enabled discrimination of cytokine-producing cells based on distinct morphological staining criteria. Cells making IL-2, IFN-gamma and TNF-alpha could be identified by a characteristic, intracellular, rounded, juxtanuclear immunofluorescence signal. This staining pattern reflected the accumulation of the intracellularly processed cytokines in the Golgi organelle of producer cells. The staining of cells that synthesized IL-1beta, which is not transported intracellularly via the endoplasmatic reticulum-Golgi pathway, generated a different, but distinct and reproducible staining pattern, IL-1beta producing macrophages expressed intense nuclear immunofluorescence with additional reticular, cytoplasmic signals. Furthermore, the use of biologically neutralizing detecting antibodies against the cytokines under study prevented recognition of surface-stained target cells that had bound secreted cytokines by cytokine-specific receptors. This modified staining technology enabled analysis of the kinetic pattern and the frequency of cytokine-producing cells in cultures of rat splenocytes after various modes of polyclonal activation.

Single-cytokine-producing CD4 memory cells predominate in type 1 and type 2 immunity

The patterns of Ag-induced cytokine coexpression in normal, in vivo-primed CD4 memory T cells has remained controversial because the low frequency at which these cells occur has effectively prevented direct ex vivo measurements. We have overcome this limitation by using two-color cytokine enzyme-linked immunospot assays and computer-assisted image analysis. We found CD4 memory cells that simultaneously expressed IL-2, IL-3, IL-4, IL-5, and IFN-gamma to be rare (0-10%). This cytokine segregation was seen in adjuvant-induced type 1, type 2, and mixed immunity to OVA, in Leishmania infection regardless of the Ag dose used or how long after immunization the assay was performed. The data suggest that type 1 and type 2 immunity in vivo is not mediated by classic Th1 or Th2 cells but by single-cytokine-producing memory cells.

Double staining of intracellular cytokine proteins and T-lymphocyte subsets. Evaluation of the method in blood and bronchoalveolar lavage fluid

An immunocytochemical staining method has been developed for simultaneous staining of both cell surface markers (CD4 and CD8) and intracellular cytokine proteins IFN-gamma, IL-4 and IL-5. Cell surface molecules were visualized with alkaline phosphatase, which was developed by Fast Blue BB. Intracellular cytokine proteins were detected by amino-ethyl carbazole. We applied this technique to T cells from T-cell lines and T-cell clones, peripheral blood mononuclear cells and broncho-alveolar lavage fluid cells. Cells were used either unstimulated or stimulated for 4 h with 1 ng/ml PMA and 1 microg/ml ionomycin, which proved to be an optimal stimulus taking cytokine staining, cell recovery and cell viability into account. We studied peripheral blood mononuclear cells from healthy subjects and found that without in vitro stimulation on average 0.4% of the cells were IFN-gamma positive cells. In unstimulated broncho-alveolar lavage fluid cells of the 2 allergic asthmatic subjects studied so far we found higher numbers of cytokine-positive cells (up to 22% of the lymphocytes being IL-4+ cells). By in vitro stimulation, the numbers of cytokine-positive peripheral blood mononuclear cells from the healthy subjects were increased to maximally 5% IFN-gamma+ cells. In stimulated lavage fluid cells from allergic asthmatic subjects maximally 34% of the lymphocytes became IFN-gamma+. We conclude that this method allows detection of intracellular cytokine proteins in both CD4+ and CD8+ T cells without the need for stimulating the cells in vitro. In vitro stimulation may change the cytokine profile detected.

Intrathecal grafting of unencapsulated adrenal medullary tissue can bring CD4 T lymphocytes into CSF: a potentially deleterious event for the graft

Adrenal medullary tissue including chromaffin cells was grafted intrathecally in cancer patients to relieve intractable pain. The central nervous system (CNS) is considered an immune privileged site. Therefore, non-HLA-matched and unencapsulated tissue was grafted in 15 patients and 1 sham control in a series of at least 20 grafts. We observed an increase in CSF lymphocyte counts in 15/20 allografts (75%). In contrast to peripheral blood, CD4 T cells predominated in the CSF, but failed to exhibit an activated phenotype (CD25+ CD45RO+ HLA-DR+). The positive effect of graft on pain, the high met-enkephalin levels, the absence of any increase in CSF cytokine levels particularly for IFN-gamma or IL-2 (but not IL-10 and IL-6), indirectly indicated that the graft was tolerated despite the presence of CSF lymphocytes. The single treatment failure and three of four cases of partial efficacy occurred in grafts where CSF lymphocytes were present. Moreover, when assayed (n = 7), the CD4+ CSF lymphocytes still retained the capacity to exhibit ex vivo a normal or enhanced frequency of T CD4 cells producing IFN-gamma and IL-2. Taken together, our observations indicate that impairment of the local immunosuppressive balance can lead to activation of those CSF CD4 T cells and drive a rejection process. This study suggests further work on the purification and/or the immunoisolation of tissues grafted in the CNS will be necessary, particularly when the possibility of long-term and repeated grafting is considered.

IGF-I increases interferon-gamma and IL-6 mRNA expression and protein production in neonatal mononuclear cells

Neonates are vulnerable to infections because of their immature immunity. IGF-I has been reported to have profound positive effects on immune function. In this study, we investigated the effects of IGF-I on neonatal immunity. The production of IL-2, IL-4, and interferon-gamma in phytohemagglutinin (PHA)-stimulated neonatal mononuclear cells (MNC) was significantly decreased when compared with that of adults. IGF-I alone induced a high level of IL-6 mRNA expression and protein production in neonatal MNC. IGF-I significantly increased mRNA expression and protein production of both IL-6 and interferon-y but had no influence on that of IL-2 and IL-4 in PHA-stimulated neonatal MNC. Moreover, it increased neonatal interferon-gamma production in PHA-stimulated MNC to a level similar to that of adults. IGF-I could further enhance the mRNA expression of lymphocyte-activation gene 3, which is associated with interferon-gamma production and differentiation of T-helper 1 lymphocytes, in PHA-stimulated neonatal MNC. These results suggest IGF-I could promote maturation of neonatal T cells, and its potential use to enhance neonatal immunity deserves further study.

Enzymatic signal amplification for sensitive detection of intracellular antigens by flow cytometry

Flow cytometry is the method of choice for the analysis of single cells with respect to the expression of specific antigens. Antigens can be detected with specific antibodies either on the cell surface or within the cells, after fixation and permeabilization of the cell membrane. Using conventional fluorochrome-labeled antibodies several thousand antigens are required for clear-cut separation of positive and negative cells. More sensitive reagents, e.g., magnetofluorescent liposomes conjugated to specific antibodies permit the detection of less than 200 molecules per cell but cannot be used for the detection of intracellular antigens. Here, we describe an enzymatic amplification technique (intracellular tyramine-based signal amplification, ITSA) for the sensitive cytometric analysis of intracellular cytokines by immunofluorescence. This approach results in a 10 to 15-fold improvement of the signal-to-noise ratio compared to conventional fluorochrome labeled antibodies and permits the detection of as few as 300-400 intracellular antigens per cell.

Reduced NFAT1 Protein Expression in Human Umbilical Cord Blood T Lymphocytes

Umbilical cord blood (UCB) stem cells from related and unrelated allogeneic donors have emerged as novel treatment for patients with hematologic malignancies. The incidence and severity of acute graft-versus-host disease (GVHD) after UCB transplantation compares favorably with that observed in recipients of matched unrelated donor allogeneic grafts, but remains a major cause of morbidity and mortality. It has been shown that stimulated lymphocytes from UCB have reduced production of cytokines including interferon-γ (IFN-γ) and tumor necrosis factor- (TNF-), which play a role in GVHD pathophysiology. We investigated the molecular mechanisms underlying this reduced cytokine production by analyzing expression of nuclear factor of activated T cells-1 (NFAT1) in UCB T cells. We detected no constitutive expression of NFAT1 protein in unstimulated UCB T cells compared with adult T cells. Moreover, although NFAT1 expression in UCB T cells was upregulated after prolonged (40 hours) T-cell stimulation, it was only partially upregulated when compared with adult controls. Our observation of minimal NFAT1 expression after stimulation correlated with reduced cytoplasmic IFN-γ and TNF- production in UCB T cells studied simultaneously. Reduced NFAT1 expression may blunt amplification of donor UCB T-cell alloresponsiveness against recipient antigens, thereby potentially limiting GVHD incidence and severity after allogeneic UCB transplantation.

Reduced NFAT1 Protein Expression in Human Umbilical Cord Blood T Lymphocytes

Umbilical cord blood (UCB) stem cells from related and unrelated allogeneic donors have emerged as novel treatment for patients with hematologic malignancies. The incidence and severity of acute graft-versus-host disease (GVHD) after UCB transplantation compares favorably with that observed in recipients of matched unrelated donor allogeneic grafts, but remains a major cause of morbidity and mortality. It has been shown that stimulated lymphocytes from UCB have reduced production of cytokines including interferon-γ (IFN-γ) and tumor necrosis factor- (TNF-), which play a role in GVHD pathophysiology. We investigated the molecular mechanisms underlying this reduced cytokine production by analyzing expression of nuclear factor of activated T cells-1 (NFAT1) in UCB T cells. We detected no constitutive expression of NFAT1 protein in unstimulated UCB T cells compared with adult T cells. Moreover, although NFAT1 expression in UCB T cells was upregulated after prolonged (40 hours) T-cell stimulation, it was only partially upregulated when compared with adult controls. Our observation of minimal NFAT1 expression after stimulation correlated with reduced cytoplasmic IFN-γ and TNF- production in UCB T cells studied simultaneously. Reduced NFAT1 expression may blunt amplification of donor UCB T-cell alloresponsiveness against recipient antigens, thereby potentially limiting GVHD incidence and severity after allogeneic UCB transplantation.

Detection of intracellular cytokines in citrated whole blood or marrow samples by flow cytometry

We have used three-color flow cytometric analysis for the detection of intracellular cytokines (IFN-gamma and IL-4) in CD3(+) cells, after stimulation for 4 h with phorbol 12-myristate 13-acetate (PMA) and ionomycin in the presence of monensin. We report in the present paper a validation study for analysing IFN-gamma and IL-4 production by bone marrow (BM)-derived T cells and peripheral blood T cells after BM transplantation. Using citrate as anticoagulant for blood and marrow sampling interfered with PMA+ionomycin-based cell stimulation. Indeed, removing this anticoagulant by two washes with 10% pooled human AB serum-supplemented RPMI 1640 before cell stimulation improved the percentages of IL-4(+) (0.02+/-0.01% to 0. 47+/-0.17% without and with washes, respectively; p<0.01) and IFN-gamma(+) (6.8+/-2.75% to 39.33+/-4.6%; p<0.01) cells to levels similar to those observed in heparin-based whole blood cultures (0.38+/-0.17% IL-4(+) and 34.27+/-4.96% IFN-gamma(+) cells; p>0.05). Delaying the cell cultures for 24 h did not significantly modify the detection of IFN-gamma in washed whole blood, but significantly altered IFN-gamma secretion in culture supernatants, as assessed by ELISA. Moreover, the percentage of IFN-gamma-producing cells within the CD3(+) lymphocyte population was stable, since similar results were obtained in two or three different independent experiments performed with the same healthy donors. This method was shown to be applicable for different kinds of citrated samples, such as blood or BM-derived cells. Overall, our data suggest that in addition to allowing for the identification of cytokine-producing cell phenotype, intracellular cytokines staining using flow cytometry is more reliable than ELISA for the biological follow-up of clinical samples.

The proportion of interleukin-4, interferon-gamma and interleukin-10-positive cells in Porphyromonas gingivalis--specific T-cell lines established from P. gingivalis-positive subjects

T-cell cytokine profiles in ten adult periodontitis and seven age-matched healthy or gingivitis subjects were determined. Porphyromonas gingivalis-specific T-cell lines were established from the peripheral blood of these individuals all of whom had past or present evidence of P. gingivalis infection. FACS analysis was used to determine the percentage of CD4- and CD8-positive cells in each line staining for cytoplasmic interleukin (IL)-4, interferon-gamma and IL-10. There were no differences in the mean percentage of IL-4-, interferon-gamma- or IL-10-positive T cells between the two groups. However, the individual profiles showed that the CD4 cells in five of the seven healthy or gingivitis lines had a higher proportion of interferon-gamma-positive cells, with two lines demonstrating higher percentages of IL-10- and/or IL-4-positive CD4 cells. Five of the ten adult periodontitis lines demonstrated either equal or higher percentages of IL-4-positive and/or IL-10-positive CD4 cells. With respect to the CD8 cells, two of the seven lines established from the healthy or gingivitis subjects and six of the ten adult periodontitis lines showed profiles with a higher percentage IL-4- and/or IL-10-positive cells. When the total T-cell contribution (CD4 plus CD8) for each T-cell line was determined from the individual CD4:CD8 ratios, only one of the healthy or gingivitis lines showed a profile with a higher proportion of IL-10-positive cells, while the results for the adult periodontitis lines were the same as indicated for the CD4 cell profiles, with five lines showing a higher percentage of IL-4- and/or IL-10-positive cells. In conclusion, this study has shown that in P. gingivalis-responsive T-cell lines established from adult periodontitis and healthy or gingivitis subjects, there was a predominant trend towards a higher percentage of interferon-gamma positive cells than either IL-4- or IL-10-positive cells. However, there were variations from this trend, although whether these variations indicate true susceptibility to progressive disease has yet to be determined.

Lymphocyte stimulation by CD3-CD28 enables detection of low T cell interferon-gamma and interleukin-4 production in rheumatoid arthritis

The analysis of cytokine production is increasingly important in defining the course of an immune response and in evaluating specific therapies of immune diseases. In rheumatoid arthritis (RA), a dysregulation in T1/T2 cell balance, as defined by the production of their specific cytokines, IFN-gamma and IL-4, respectively, is suggested. A predominance of T1-cell mediated macrophage activity in the joint plays a key role in the destruction of articular cartilage and subchondral bone, whereas local T2 cell activity, mitigating disease, fails. However, analysis of the cytokines defining both T cell subsets is difficult and spontaneous production is often below detection limits. Several stimuli are therefore used to increase cytokine production. In the present study we examined whether stimulation of peripheral blood T cells in the context of mononuclear cells (PB MNC) by CD3-CD28 is a reliable method for assessing IFN-gamma and IL-4 production and is representative for the spontaneous production of these cytokines. The production of IFN-gamma and IL-4 following CD3-CD28 stimulation of RA PB MNC correlated significantly in a ratio 1 : 1 with production following ionomycin-PMA stimulation. In samples with detectable spontaneous production of IFNgamma and IL-4, production following CD3-CD28 stimulation was significantly higher than in stimulated samples with undetectable spontaneous production. Moreover, in the case of spontaneous production there was a significant positive linear correlation between the CD3-CD28 stimulated and spontaneous IFNgamma and IL-4 production, although production of both cytokines was not equally enhanced. Serial sampling did not show significant daily or weekly variation in stimulated cytokine production. The results demonstrate that a pecific T-cell stimulation by CD3-CD28 is a reliable way to enhance IFN-gamma and IL-4 production above the detection limit and so measure the T1/T2 cell balance in RA.

Differences in Type 1 and Type 2 intracytoplasmic cytokines, detected by flow cytometry, according to immunosuppression (cyclosporine A vs. tacrolimus) in stable renal allograft recipients

Recent multicenter, randomized clinical trials have shown that in renal transplant patients tacrolimus (FK506) was more efficient than cyclosporine A (CsA) at preventing acute rejection. In order to try and evaluate whether this difference was related to a different in vivo T-cell suppression we assessed, in a prospective study, the frequencies of interleukin (IL)-2-, IL-4-, IL-5-, IL-6-, IL-10-, interferon-gamma (IFN-gamma)- and double-positive IL-2/IFN-gamma-producing whole T cells, CD4 + and CD8 + T-cell subsets by means of cytokine flow cytometry. This was performed after in vitro stimulation of peripheral blood mononuclear cells (PBMCs) with phorbol myristate acetate (PMA) and ionomycin, in the presence of monensin, in 14 healthy volunteers (controls) and in 14 renal transplant patients. The immunosuppression of the latter was based either on CsA (n = 7) or on FK506 (n = 7). Cytokine-expressing T-cell frequencies were assessed immediately pretransplantation (DO), and subsequently 3 months (M3) and 6 months (M6) afterwards in fasting patients prior to the morning intake of the immunosuppressive drug. We found that at DO the frequencies of IL-2-(22 +/- 2% vs. 22.2 +/- 2%), IFN-gamma-(26 +/- 3% vs. 29 + 3.4%) and IL-4-(0.8 +/- 0.2% vs. 1.4 +/- 0.2%)-expressing T lymphocytes were not significantly different between the controls and the patients, respectively. Conversely, the frequency of IL-2/IFN-gamma double positive cells was higher in the latter (9.3 +/- 1.6%) than in the controls (5.6 +/- 0.8); p = 0.06. Finally, on D0 the frequencies of IL-5-, IL-6-, and IL-10-producing T lymphocytes were lower than 1%, in both groups, as well as after grafting, i.e. on M3 and M6. As compared to baseline (DO): (a) chronic immunosuppression significantly decreased the frequencies of IL-2-, IL-4- and IL-2/IFN-gamma-expressing T cells, whereas those of IFN-gamma, IL-5, IL-6, and IL-10 were not significantly affected; (b) the frequencies of cytokine-expressing T cells were not statistically different between M3 and M6; (c) the decrease in the frequencies of IL-2- and IL-2/IFN-gamma-expressing T cells affected CD4 + and CD8 + cells equally; (d) there was a marginal decrease in the frequency of IFN-gamma-expressing cells only in the CD4 + subset but not in the CD8 population; and (e) for CsA, but not for FK506, the frequency of the IL-2-expressing T cells was negatively correlated with the whole blood trough levels. When we compared the frequencies of cytokine-expressing cells in FK506- and CsA-treated patients, we found that the frequency of IL-2-expressing T cells was significantly lower with FK506 (10.9+/-1.61%) than with CsA (16.3 +/- 1.8%; p = 0.03), whereas the frequencies of the other cytokine-expressing cells were not statistically different between the two groups. In conclusion, our study clearly demonstrated that studied ex vivo, FK506 and CsA decrease the frequencies of cells expressing IL-2, IL-4 and IL-2/IFN-gamma in vivo but do not affect those expressing IFN-gamma. Meanwhile, the frequency of IL-2-producing T cells was more affected with FK506 than with CsA and was negatively correlated with the CsA trough level. Finally, our results regarding IL-2 might explain to some extent the higher efficiency of FK506 in vivo than CsA.

Characterization of phenotype and cytokine profiles of T cell lines derived from vitreous humour in ocular inflammation in man

Intermediate uveitis (IU) and Fuchs' heterochromic cyclitis (FHC) are two chronic ocular inflammatory disorders. They differ considerably in ocular morbidity, which is higher in IU. T cell lines were derived from the vitreous humour (VH) and peripheral blood (PB) of 10 patients with IU and four patients with FHC. There was a predominance of CD8+ in all the lines. However, there was a significantly higher percentage of CD4+ T cells in the T cell lines derived from VH of IU (32.0 +/- 8.6%) compared with FHC patients (19. 2 +/- 8.9%) (P = 0.04). The VH-derived T cell lines (VDTC) produced significantly higher levels of IL-2, interferon-gamma (IFN-gamma) and IL-10, but not IL-4, compared with PB-derived T cell lines (PBDTC) in both entities. There was significantly higher IL-2 production by VDTC from IU when compared with FHC patients (1810 +/- 220 pg/ml versus 518 +/- 94 pg/ml; P = 0.009), which could account for the more aggressive clinical features of this condition. In contrast IL-10 production was significantly higher by the VDTC from FHC compared with IU patients. The high IL-10 production by T cells infiltrating VH of FHC patients could down-regulate the inflammatory responses, thereby contributing to the benign clinical course seen in these patients. The accumulation of T cells with differing cytokine profiles in the VH suggests an important role for these cytokines in the pathogenesis of these chronic uveitides.

Self glycolipids as T-cell autoantigens

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by discrete areas of demyelination. An autoimmune response against components of myelin is thought to contribute to disease pathogenesis. Here we identify glycolipids as new targets recognized by T cells in multiple sclerosis patients. Circulating T cells reactive with glycolipids are more frequent in MS patients than in control donors as shown by enzyme-linked immunospot assay. They specifically recognize different types of glycolipids, such as gangliosides, sulfatide and galactosylceramide and release IFN-gamma and TNF-alpha. T cells specific for gangliosides were found to be CD8+, TCR alphabeta+, restricted by the MHC-like CD1b molecule and specific for epitopes residing in the carbohydrate moiety of gangliosides. Our findings suggest that in addition to self proteins, self glycolipids may represent potential source of autoantigens recognized by T cells in autoimmune diseases.

Protective Role of β-Chemokines Associated with HIV-Specific Th Responses Against Perinatal HIV Transmission

To examine the protective role of cellular immunity in the vertical transmission of HIV, we analyzed HIV-specific IL-2 and CTL responses, as well as β-chemokine expression in HIV-infected and uninfected infants of HIV+ mothers. Our results showed that HIV envelope (env) peptide-specific IL-2 responses associated with β-chemokine production were detectable at birth in the majority of uninfected infants of HIV+ mothers. The responses falling to background before the infants were 1 yr old were rarely associated with HIV-specific CTL activity. Conversely, HIV-specific Th and CTL cellular responses were absent at birth in HIV-infected infants. Infants with AIDS-related symptoms exhibited undetectable or very low levels of HIV-specific cellular immunity during the first year of life, whereas those with a slowly progressive disease showed evidence of such immunity between their second and ninth month. The latter group of infected infants tested negative for plasma HIV RNA levels shortly after birth, suggesting lack of intrauterine exposure to HIV. The presence of HIV-specific Th responses at birth in uninfected newborns of HIV+ mothers, but absence of such activities in HIV-infected infants without evidence of intrauterine HIV infection, suggests that in utero development of HIV-specific Th responses associated with β-chemokines could mediate nonlytic inhibition of infection during vertical transmission of HIV.