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

Differentiation of human single-positive fetal thymocytes in vitro into IL-4- and/or IFN-gamma-producing CD4+ and CD8+ T cells

In this study we have investigated the capacity of human fetal thymocytes to differentiate in vitro into subsets of T cells with polarized Th1 or Th2 cytokine profiles. Stimulation of freshly isolated human fetal thymocytes with anti-CD3 mAb, cross-linked onto CD32,CD58,CD80-expressing mouse fibroblasts and subsequent culture in the presence of exogenous rIL-2 for 6 days, induced the production of both IL-4 and IFN-gamma, which was mainly produced by CD4+ single-positive (SP) and CD8+ SP cells respectively. Addition of rIL-4 during priming augmented IL-4 production in cultures of human fetal thymocytes, which was mainly due to an increased production of IL-4 by CD8SP cells. In contrast, addition of IL-4 to the cultures only slightly enhanced IL-4 production and had little effect on frequencies of IL-4-producing CD4SP cells. Both CD4SP and CD8SP cells produced IL-5, IL-10 and IL-13 at comparable levels, following priming in the presence of rIL-4. Priming in the presence of rIL-12 strongly enhanced the production of IFN-gamma in both CD4SP and CD8SP cells. No correlation between expression of CD27, CD30 and CD60, and a particular cytokine profile of differentiated thymocytes could be demonstrated. Together, these results demonstrate the full capacity of fetal human thymocytes to differentiate into cytokine-producing T cells in a priming milieu with appropriate stimulatory molecules and exogenous cytokines. In addition, CD4SP thymocytes rapidly differentiate into polarized Th2 cells following stimulation in vitro in the absence of exogenous rIL-4.

Kinetics of intracytoplasmic Th1 and Th2 cytokine production assessed by flow cytometry following in vitro activation of peripheral blood mononuclear cells

BACKGROUND

Standard cytokine detection methods are unable to determine which cells are the producing cells. We report on the extent and under which conditions the multilabeling capability of flow cytometry (FCM) can bring new advances into the field.

METHODS

Five different cytokines, interleukin-2 (IL-2), -4, -5, -10 and interferon-gamma (IFN-gamma), were assessed simultaneously under five ex vivo stimulation conditions in peripheral blood mononuclear cells from five healthy volunteers in a 5-day kinetic study. A second group of 35 volunteers was assessed for IFN-gamma and IL-2 production.

RESULTS

This study showed that (a) intracytoplasmic cytokines were almost undetectable within unstimulated cells, (b) intracytoplasmic cytokines were detected only in CD69(+) T lymphocytes, and (c) intracytoplasmic IL-2 and IFN-gamma were dramatically upregulated after stimulation with phorbol myristate acetate (PMA)-ionomycin in a biphasic response or with PMA-phytohemagglutinin (one major peak only at 18 h) but to a lesser extent with other stimuli such as monoclonal antibodies. Th2 cytokines were detected at a later time point and at lower levels. PMA/ionomycin stimulation after 4 h and 18 h of culture in 35 other volunteers individualized several subgroups according to the frequency of IFN-gamma- or IL-2-producing cells--IFN-gamma delayed producers (n = 10/35), IFN-gamma low producers (n = 8/35), and IL-2 delayed producers (n = 16/35)--as opposed to IFN-gamma or IL-2 normal producers.

CONCLUSIONS

FCM appears to be a good tool to examine cell cytokine status in pathology (allergy, autoimmune disease, etc.) provided that optimal stimulation conditions and multiple time-point cultures are used. It also seems to be a relevant method to define new Th subsets further.

Effects of tumour necrosis factor alpha and melphalan on the cytokine production of circulating T cells in patients with cancer

BACKGROUND

The objective of the present study was to investigate the effects of isolated limb perfusion (ILP) with tumour necrosis factor alpha (TNF-alpha) and melphalan on circulating T cells from cancer patients using two different methods.

DESIGN

Eight patients undergoing an ILP entered the study. At first, the number of T cells at several time points was determined using FACScan. Subsequently, production of interferon gamma (IFN-gamma) (T-helper 1) and interleukin (IL) 4 (T-helper 2) was measured at the intracytoplasmic level after stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin. IFN-gamma, IL-4 and IL-2 (also T-helper 1) production in the whole-blood cell culture system was then determined after stimulation with a combination of anti-CD3/anti-CD28 monoclonal antibodies.

RESULTS

An enormous decrease in the number of circulating T cells was observed. In the remaining T-cell population cytokine production (IL-2, IL-4, IFN-gamma) was depressed, showing the same pattern in both methods. No difference could be detected between the effect of TNF-alpha and melphalan on Th1 cells and Th2 cells.

CONCLUSIONS

The results demonstrate that TNF-alpha and melphalan reduce the number of circulating T cells and at the single-cell level decrease cytokine production in the remaining circulating T cells. No selective effect of TNF-alpha on Th1 or Th2 cells could be detected. If the impaired T-cell function is representative of all T cells remaining in the systemic circulation, this could help to explain the tolerability of high TNF concentrations after ILP, perhaps by decreasing the synthesis and production of T-cell-derived cytokines.

T Cell Priming Enhances IL-4 Gene Expression by Increasing Nuclear Factor of Activated T Cells

The repetitive activation of T cells (priming) enhances the expression of many cytokines, such as IL-4, but not others, such as IL-2. Molecular mechanisms underlying selective expression of cytokines by T cells remain poorly understood. Here we show that priming of CD4 T cells selectively enhances IL-4 expression relative to IL-2 expression by a transcriptional mechanism involving nuclear factor of activated T cells (NFAT) proteins. As detected by in vivo footprinting, priming markedly increases the activation-dependent engagement of the P0 and P1 NFAT-binding elements of the IL-4 promoter. Moreover, each proximal P element is essential for optimal IL-4 promoter activity. Activated primed CD4 T cells contain more NFAT1 and support greater NFAT-directed transcription than unprimed CD4 T cells, while activator protein 1 binding and activator protein 1-mediated transcription by both cell types is similar. Increased expression of wild-type NFAT1 substantially increases IL-4 promoter activity in unprimed CD4 T cells, suggesting NFAT1 may be limiting for IL-4 gene expression in this cell type. Furthermore, a truncated form of NFAT1 acts as a dominant-negative, reducing IL-4 promoter activity in primed CD4 T cells and confirming the importance of endogenous NFAT to increased IL-4 gene expression by effector T cells. NFAT1 appears to be the major NFAT family member responsible for the initial increased expression of IL-4 by primed CD4 T cells.

Cytomegalovirus-specific IFNgamma and IL-4 are produced by antigen expanded human blood lymphocytes from seropositive volunteers

The cytokine responses to cytomegalovirus (CMV) antigen in seropositive and seronegative individuals were measured using a combination of antigenic expansion and intracellular staining. Intracellular IFNgamma and IL-4 were produced in a dose-dependent manner by T cells in response to CMV only in the seropositive population. The potential for individual cells to produce both Th1 and Th2 cytokines simultaneously was clear, as IL-4 was most often produced in those cells with the highest IFNgamma production. The cytokine-specific nature of this response was demonstrated by fluorescence microscopy, which showed granular cytoplasmic staining, and at the mRNA level by ribonuclease protection assays. These methods expand our ability to evaluate the immune response to CMV, and can now be correlated to a number of clinical conditions.

Dynamics of intra-hepatic lymphocytes in chronic hepatitis C: enrichment for Valpha24+ T cells and rapid elimination of effector cells by apoptosis

Chronic viral hepatitis is characterized by a dramatic lymphocyte infiltrate in the liver. Although it is one of the most common chronic inflammatory diseases in humans, little information is available on the functional state of these intra-hepatic lymphocytes (IHL). To address this issue, we have optimized cytofluorimetric techniques to assess directly ex vivo the functions, dynamics and repertoires of IHL isolated from biopsies of patients with chronic hepatitis C. We estimate that 1% of the total body lymphocytes infiltrate the inflamed liver and find that, at variance with peripheral blood lymphocytes (PBL) isolated from the same patients, most IHL display an activated phenotype and produce Th1 type lymphokines when stimulated in vitro. Virtually all IHL are found in the G0/G1 state of the cell cycle, while a sizeable percentage of them is undergoing programmed cell death in vivo, as detected by the TUNEL assay performed on freshly isolated cells. In contrast again to PBL from the same patients, IHL show a preferential compartmentalization of NK and TCRgamma/delta+ cells, and a remarkable (up to 20-fold) enrichment for Valpha24+ T cells. Together our data suggest that in a liver injured by chronic hepatitis C, most IHL are pro-inflammatory activated cells which are highly enriched for effectors of innate resistance. These IHL do not undergo clonal expansion in the liver but rather display effector function and die in situ at a high rate, suggesting that maintenance of the IHL pool is dependent on continuous migration from extra-hepatic sites.

Cytokine profiles of lesional and splenic T cells in Porphyromonas gingivalis infection in a murine model

T cell cytokine profiles in the spleens and Porphyromonas gingivalis-induced lesions of P. gingivalis-immunized mice were examined. BALB/c mice were immunized with P. gingivalis outer membrane (OM) antigens/mouse weekly for 3 weeks followed by challenge with live organisms 2 weeks after the final immunization. Control mice were immunized with PBS. Spleens were excised at 0 and 4 days and lesions at 1, 4, and 7 days after challenge. Splenic and lesional CD4 and CD8 cells were stained for intracytoplasmic interleukin (IL)-4, interferon (IFN)-gamma, and IL-10. More than 50% of the T cells in the spleens of immunized mice were IFN-gamma positive at day 0 which was significantly higher than for IL-4 or IL-10, these levels decreasing significantly 4 days after challenge. Less than 6% of the T cells in sham immunized mice were cytokine positive at day 0, although at day 4, there was a significant increase in the percent IL-10 positive CD4 cells and IL-4 and IL-10 positive CD8 cells. There were no differences in the percent IL-4, IFN-gamma, or IL-10 positive T cells in the lesions of immunized mice, but there was a dramatic decrease at day 7 to very low levels in control mice. In conclusion, the results of the present study show a predominant Th1 response in the spleens of BALB/c mice after immunization with P. gingivalis OM antigens, suggesting that a protective immune response to P. gingivalis may involve a strong IFN-gamma response.

Frequencies of T cells expressing interleukin-4 and interleukin-5 in atopic asthmatic children. Comparison with atopic asthmatic adults

T-cell-derived cytokines have been implicated in the pathogenesis of asthma and it has been suggested that Th2-type cytokines (interleukin-4 [IL-4], interleukin-5 [IL-5]) are pivotal in the allergic inflammation. However, there are little data on human cytokine production by individual T cells at the protein level, in particular in asthmatic children. In this study we analyzed the cytokine production at the single cell level in peripheral blood from mild atopic asthmatic (AA) children and adults and age-matched atopic nonasthmatic (AN) and nonatopic nonasthmatic (NN) control subjects (n = 9 in each group) using the technique of intracellular cytokine detection by flow cytometry. Comparing asthmatic children with atopic and nonatopic control subjects, an increased percentage of IL-5-producing T cells (AA: median 4.9% [range 1.1 to 8.9%]; AN: 0.3% [0.2 to 0.9%], p = 0.003; NN: 0.4% [0.1 to 3.8%], p = 0.001) was detectable, with a positive correlation to the number of peripheral eosinophils and to bronchial hyperresponsiveness. The frequency of IL-4-producing T cells was increased in both atopic groups compared with nonatopic controls (AA: 1.2% [0.2 to 2.6%], p = 0.011; AN: 0.8% [0.4 to 3.7%], p = 0.007; NN: 0.4% [0.2 to 0.9%]) with a positive correlation to total IgE concentration. In adults there were no differences in IL-5- or IL-4-producing T cells between all three groups. A substantial proportion of T cells coproducing IL-4 and IL-5 was not detectable in children and adults. These findings indicate that in asthmatic children the frequencies of Th2-type-producing T cells are increased and that expression of IL-4 and IL-5 is regulated independently.

Cytokine mRNA and protein expression in a mixed leukocyte reaction before and after allogeneic transfusions. Groupe Coopératif de Transplantation d'Ile de France

BACKGROUND

The precise mechanism by which pretransplant blood transfusions may favorably influence the graft outcome in human transplantation remains unknown. Here, we explored whether the mechanism might be related to an alteration of cytokine response to transplantation antigens.

METHODS

Eight patients awaiting kidney transplantation were selected to receive a single planned pretransplant blood transfusion. Before transfusion and 7 days after transfusion, peripheral blood mononuclear cells from these patients were isolated and in vitro stimulated in a one-way mixed leukocyte reaction (MLR) by using allogeneic fixed Epstein Barr virus-transformed cells as stimulators.

RESULTS

The use of a semiquantitative reverse-transcriptase polymerase chain reaction cycle technique to analyze cytokine mRNAs revealed that allostimulation by donor cells clearly induced accumulation of interleukin (IL)-2, IL-4, interferon (IFN)-gamma, and IL-10 mRNA in peripheral blood mononuclear cells collected both before and after transfusion (eight of eight patients). However, both T helper 1 (IFN-gamma) and T helper 2 (IL-4) cytokine responses were more elevated after transfusion in eight of eight patients, as were IL-2 responses in five of eight patients. Such up-regulation of cytokine responses by transfusion was mostly directed against blood donor cells. Indeed, after stimulation by third-party cells, this up-regulation was both inconstant (two of three patients) and of less intensity, and no change was detected after stimulation by autologous cells (three of three patients).

CONCLUSIONS

That IL-2, IL-4, and IFN-gamma responses to donor cells were increased by transfusion was further supported by results on cytokine secretion showing increased levels of IL-2 (P < 0.05), IFN-gamma (P = 0.054), and IL-4 (P < 0.05) proteins in supernatants of posttransfusion MLR as compared with pretransfusion MLR. In contrast, transfusion-induced changes in the amount of IL-10 mRNAs were not obvious and were quite variable from one patient to another.

Detection of and discrimination between total and free human interleukin-4 and free soluble interleukin-4 receptor by ELISA

Interleukin-4 (IL-4) signaling is initiated by binding of IL-4 to the high-affinity IL-4 receptor alpha-chain and subsequent interaction with the common gamma-chain. Soluble forms of the extracellular domain of the alpha-chain (sIL-4R) were shown to be present in biological fluids and, dependent on the concentration, enhance or inhibit IL-4 activity by forming IL-4/sIL-4R complexes. To discriminate between free and potentially active IL-4 from the inactive and complexed form, we have established a set of new ELISA systems for the measurement of human IL-4 in its distinct forms. To select suitable pairs of anti-IL-4 antibodies, a chequerboard interference analysis with six highly-selective human IL-4 specific monoclonal antibodies was performed. For the determination of total IL-4, a monoclonal capture antibody was used that binds IL-4 outside the binding site of the IL-4R alpha-chain. Another antibody recognizing an epitope of the alpha-chain binding site was chosen for the detection of free IL-4. The binding of this antibody was inhibited in a dose-dependent fashion by recombinant sIL-4R. Assays for both total and free IL-4 exhibited a sensitivity of 8 pg/ml and a dynamic range up to 1000 pg/ml. Human sIL-4R was detected by two monoclonal antibodies directed against different epitopes. This ELISA was inhibited by recombinant IL-4 suggesting the measurement of predominantly free sIL-4R. Complexes between soluble IL-4R and IL-4 were detected by a monoclonal anti-sIL-4R antibody in combination with an anti-IL-4 antibody. When supernatants of activated T cells were analyzed, the majority of the IL-4 was in free form. The amount of complexed IL-4 was low as indicated by the fact that most of total IL-4 could be detected as free IL-4. Although values obtained for complexed IL-4 correlated with the difference between total and free IL-4, precise values could not be determined, presumably due to the dynamic nature of the complex between the two proteins. We suggest that the ability to quantitate total and free IL-4 in combination with sIL-4R may provide a new insight of the role that IL-4 plays in different pathophysiological conditions.

Intracellular Cytokine Profile of Cord and Adult Blood Lymphocytes

Umbilical cord blood (CB) transplantation is thought to be associated with a reduced risk of severe graft-versus-host-disease (GVHD) compared with bone marrow transplantation (BMT). The cytokine cascade is known to be important in the pathogenesis of GVHD; however, previous studies investigating the cytokine secretion pattern of CB cells have been contradictory because of variations in experimental techniques. In this study, the cytokine profile of cord and adult blood lymphocytes and lymphocyte subsets has been assessed at the single-cell level by flow cytometry, using CD4/CD8 and CD45RA/CD45RO markers. Cord and adult blood mononuclear cells were stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin in the presence of monensin. After 4 to 24 hours of incubation, interleukin-2 (IL-2), IL-4, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) production was measured by three-color flow cytometry. The results show that cord blood lymphocytes (CBL) produce less IL-2, IL-4, IFN-γ, and TNF-α than adult peripheral blood lymphocytes (ABL). Further subset analysis showed that in CBL the majority of cytokine producing cells were CD4+CD45RA+, whereas in ABL the cytokine-producing cells were both CD4+CD45RO+ and CD8+CD45RO+. These results suggest that the reduced incidence of GVHD in CB transplantation may partly due to the altered cytokine profile seen in CBL.

Generation, Persistence, and Modulation of Th0 Effector Cells: Role of Autocrine IL-4 and IFN-γ

Many studies have classified CD4 responses into either Th1-like or Th2-like, based on cytokine secretion profiles, but little significance has been placed on Th0 cells. This has largely resulted from studies that suggested that Th0 populations primarily comprise individual Th1 and Th2 cells. Here, we show that priming of Ag-specific naive CD4 cells with moderate dose IL-4 generates a Th0 population that is evident after 3 days in vitro and becomes prevalent after successive encounters with Ag over a 9-day period. By intracellular cytokine staining, the majority (&gt;60%) of effector cells generated in this way produce either IL-4, IFN-γ and IL-2, or IL-4 and IFN-γ without IL-2. Endogenous IFN-γ secreted over the initial 3 days of culture was critical for generating Th0 cells, since neutralization allowed IL-4 to induce differentiation into Th2-like cells. Successive encounters with Ag were required for generating Th0 cells, and their stability and persistence were governed by the balance of endogenous IL-4 and IFN-γ secreted during the later stages of differentiation. Studies blocking Fas-induced cell death showed that this process played no role in Th0 cell generation, and differential death of committed Th1 or Th2 cells was not required for Th0 persistence. These data suggest that Th0 cells can be as prevalent as Th1- or Th2-like cells after naive CD4 activation, that the relative levels of autocrine IL-4 and IFN-γ are important to the lack of commitment, and that not all cells are predestined to the Th1 or Th2 phenotypes early in the response.

Stable expression of manganese superoxide dismutase (MnSOD) in insulinoma cells prevents IL-1beta- induced cytotoxicity and reduces nitric oxide production

The fact that insulin-producing islet beta-cells are susceptible to the cytotoxic effects of inflammatory cytokines represents a potential hinderance to the use of such cells for transplantation therapy of insulin-dependent diabetes mellitus (IDDM). In the current study, we show that IL-1beta induces destruction of INS-1 insulinoma cells, while having no effect on a second insulinoma cell line RIN1046-38 and its engineered derivatives, and that this difference is correlated with a higher level of expression of manganese superoxide dismutase (MnSOD) in the latter cells. Stable overexpression of MnSOD in INS-1 cells provides complete protection against IL-1beta-mediated cytotoxicity, and also results in markedly reduced killing when such cells are exposed to conditioned media from activated human or rat PBMC. Further, overexpression of MnSOD in either RIN- or INS-1-derived lines results in a sharp reduction in IL-1beta-induced nitric oxide (NO) production, a finding that correlates with reduced levels of the inducible form of nitric oxide synthase (iNOS). Treatment of INS-1 cells with L-NMMA, an inhibitor of iNOS, provides the same degree of protection against IL-1beta or supernatants from LPS-activated rat PBMC as MnSOD overexpression, supporting the idea that MnSOD protects INS-1 cells by interfering with the normal IL-1beta-mediated increase in iNOS. Because NO and its derivatives have been implicated as critical mediators of beta-cell destruction in IDDM, we conclude that well regulated insulinoma cell lines engineered for MnSOD overexpression may be an attractive alternative to isolated islets as vehicles for insulin replacement in autoimmune diabetes.

The Cytokine Profile Expressed by Human Dendritic Cells Is Dependent on Cell Subtype and Mode of Activation

In the present study, we have analyzed the pattern of cytokines expressed by two independent dendritic cell (DC) subpopulations generated in vitro from human cord blood CD34+ progenitors cultured with granulocyte-macrophage CSF and TNF-α. Molecularly, we confirmed the phenotypic differences discriminating the two subsets: E-cadherin mRNA was only detected in CD1a+-derived DC, whereas CD68 and factor XIIIa mRNAs were observed exclusively in CD14+-derived DC. Semiquantitative reverse-transcriptase PCR analysis revealed that both DC subpopulations spontaneously expressed IL-1α, IL-1β, IL-6, IL-7, IL-12 (p35 and p40), IL-15, IL-18, TNF-α, TGF-β, macrophage CSF, and granulocyte-macrophage CSF, but not IL-2, IL-3, IL-4, IL-5, IL-9, and IFN-γ transcripts. Both subpopulations were shown to secrete IL-12 after CD40 triggering. Interestingly, only the CD14+-derived DC secreted IL-10 after CD40 activation, strengthening the notion that the two DC subpopulations indeed represent two independent pathways of DC development. Furthermore, both DC subpopulations expressed IL-13 mRNA and protein following activation with PMA-ionomycin, but not with CD40 ligand, in contrast to IL-12 and IL-10, revealing the existence of different pathways for DC activation. Finally, we confirmed the expression of IL-7, IL-10, and IL-13 mRNA by CD4+CD11c+CD3− DC isolated ex vivo from tonsillar germinal centers. Thus, CD14+-derived DC expressing IL-10 and factor XIIIa seemed more closely related to germinal center dendritic cellsGCDC than to Langerhans cells.

Cytokine profiles of cells extracted from humans with periodontal diseases

FACS analysis was used to determine the percent interferon (IFN)-gamma-, interleukin (IL)-4-, IL-10-, and CD30-positive T-cells extracted from adult periodontitis (AP) and healthy/gingivitis (H/G) subjects. Additionally, the percentages of IL-1 beta-, IL-10- and IL-12-producing B-cells and macrophages were ascertained. The percent IL-10+ CD8 cells extracted from AP lesions was decreased compared with H/G tissues (p = 0.033), and the percent CD30+ CD4 (p = 0.001) and CD30+ CD8 (p = 0.028) cells was higher in AP than in H/G tissues. The percentages of IL-1 beta + macrophages (p = 0.003) and IL-12+ B-cells (p = 0.034) were both higher in AP lesions than in H/G tissues. The specific effect of Porphyromonas gingivalis on the cytokine profiles of peripheral blood mononuclear cells isolated from P. gingivalis-infected AP and H/G patients was also determined. While there were no significant differences in the percent cytokine-positive T-cells after stimulation with P. gingivalis outer membrane antigens (OM) for 6 days compared with cells incubated in medium only, the percent CD30+ CD4 cells increased significantly (p = 0.047 and p = 0.063 for AP and H/G groups, respectively). There was also an increase in the percent IL-1 beta + B-cells from AP patients (p = 0.029), and the percent IL-12+ monocytes from AP and H/G subjects was higher than the percent IL-12+ B-cells, both after stimulation with P. gingivalis OM (p = 0.005 for the AP group and p = 0.058 and therefore not quite significant for the H/G group) and when incubated in medium alone (p = 0.016 and p = 0.015 for AP and H/G groups, respectively). This study has shown that IL-10+ CD8 cells may be significant in gingival lesions, and that CD30+ T-cells indicative of Th2 or Th0 cells may play a role in progressive periodontal disease. This study has also shown that B-cells produce IL-1 in the gingival lesion and that P. gingivalis may be significant in the induction of B-cell-induced IL-1.

Opposite role for interleukin-4 and interferon-gamma on CD30 and lymphocyte activation gene-3 (LAG-3) expression by activated naive T cells

Polarized human type 1 and type 2 T helper cells not only produce different sets of cytokines, but they also preferentially express certain activation markers, such as lymphocyte activation gene-3 (LAG-3) and CD30, respectively. In this study we have examined the LAG-3 and CD30 expression in relation to the lineage commitment of human naive CD4+ T cells, as assessed at the single-cell level of committed T cells. Purified CD45RA+ umbilical cord blood T lymphocytes were activated with phytohemagglutinin and interleukin (IL)-2 in the absence or presence of interleukin IL-4 or IL-12 and assessed for CD30 and LAG-3 expression, as well as for intracellular cytokine synthesis. Significant numbers of CD30+ cells were only found in CD4+ and CD8+ T lymphocytes of cultures primed with IL-4, which developed into cells able to produce IL-4 and IL-13 in addition to interferon (IFN)-gamma. By contrast, LAG-3 expression was strongly up-regulated in CD4+ and CD8+ T cells from cultures primed with IL-12, which developed into high numbers of IFN-gamma producers. The addition of a neutralizing anti-IFN-gamma antibody to IL-12-primed CD4+ T cell cultures virtually abolished the development of LAG-3-expressing CD4+ T cells. Taken together, these data suggest that CD30 expression is dependent on the presence of IL-4, whereas LAG-3 expression is dependent on the production of IFN-gamma during the lineage commitment of human naive T cells.

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.

Immunocytochemical and flow cytofluorimetric detection of intracellular IL-4, IL-5 and IFN-gamma: applications using blood- and airway-derived cells

We have compared an immunocytochemical and a flow cytofluorimetric method to detect intracellular IFN-gamma, IL-4 and IL-5 in T-cell clones, peripheral blood mononuclear cells (PBMC) and bronchoalveolar lavage fluid (BALF) cells. Intracellular bound cytokine-specific antibodies were visualized either with amino-ethyl carbazole (for immunocytochemistry), or with fluorescent antibodies (for flow cytofluorimetry). The staining was inhibited with recombinant cytokines and corresponded qualitatively and quantitatively to cytokine levels in the supernatants of T-helper-0 (Th0), Th1 and Th2 clones. In analysing in vitro stimulated cells, sufficient signal in the fluorimetric assay was only obtained after the addition of monensin to the cultures. We then observed a good correlation between immunocytochemical (with no monensin added) and the flow cytofluorimetric staining for all three cytokines (PBMC, IFN-gamma and IL-4, rho = 0.9, no IL-5 detectable; clones, IL-5, rho = 0.81, all three p < 0.05). However, compared to flow cytometry, a greater percentage of positively stained cells was frequently observed using immunocytochemistry. In BALF cells, the immunocytochemical method was able to detect significant percentages of positive cells without in vitro stimulation of the cells, in contrast to the flow cytofluorimetric method. In BALF cells from sarcoidosis patients, T-cells were mainly IFN-gamma-positive (immunocytochemically assessed), both with (mean +/- SEM, 39.7 +/- 9.8%), and without (3.5 +/- 1.3%) in vitro stimulation. In BALF cells from allergic subjects, the immunocytochemical method showed lymphocytes positive for IFN-gamma (40.3 +/- 8.3%), IL-4 (19.1 +/- 0.49) and IL-5 (6.1 +/- 3.1). We conclude that both methods can be used to assess the production of IFN-gamma, IL-4 or IL-5 at the single-cell level in T-cell clones, PBMC and cells from the BALF. The high sensitivity and the low number of cells required for the immunocytochemical method indicate that this method can provide detailed information on cytokine production of airway-derived cells in diseases with airway inflammation such as sarcoidosis and asthma.

Interleukin-10 production by cord blood mononuclear cells

The production of IL-10 by newborns has not been studied in much detail. We analyzed the IL-10 production by, and surface marker distribution of, cord blood mononuclear cells (n = 47); adult peripheral blood mononuclear cells (n = 30) were used as controls. Both the baseline (0.79 versus 1.54 ng/mL, p = 0.001) and lipopolysaccharide-stimulated (1.20 versus 2.88 ng/mL, p = 0.003) levels of IL-10 production were significantly lower in newborns than in adults. No significant differences were observed after stimulation with concanavalin A. Both cord blood and adult CD19+CD5+ cells were able to produce IL-10; however, the level of production was only an average of 16% of the total stimulated IL-10 production by unfractionated cells, indicating that CD5+ B cells are not the primary source of IL-10 in either adults or newborns. In newborns, the proportion of naive CD4+CD45RA+ cells was inversely correlated with IL-10 response to lipopolysaccharide (r = -0.49, p = 0.004) indicating a role for maturing T cells in neonatal IL-10 production; the number of macrophages was not significantly correlated with IL-10 response (r = 0.30, p = 0.10). In contrast, in adults IL-10 production correlated with the number of macrophages (r = 0.49, p = 0.01) but not CD4+CD45RA+ cells (r = -0.06, p = 0.77). We conclude that newborns produce less IL-10 than adults; the primary cells of origin and the regulatory mechanisms may be different from those observed in adults.

Shift toward T lymphocytes with a T helper 1 cytokine-secretion profile in the joints of patients with rheumatoid arthritis

OBJECTIVE

To investigate whether T cells in the inflamed joints of patients with rheumatoid arthritis (RA) preferentially produce the T helper 1 (Th1) cytokines, interferon-gamma (IFN gamma) and interleukin-2 (IL-2), or the Th2 cytokine, IL-4, when compared with corresponding peripheral blood-derived T cells.

METHODS

Synovial fluid mononuclear cells (SFMC) and corresponding peripheral blood mononuclear cells (PBMC) from 10 patients with RA were analyzed, either directly or after in vitro stimulation, for the intracellular presence of Th1 and Th2 cytokines. The amount of secreted cytokine in the cell culture supernatants was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

IFN gamma-containing cells were detected in the unstimulated SFMC, but not in the PBMC, of 3 patients with RA. Cells positive for IL-2 or IL-4 were not detected in the unstimulated samples. Following stimulation, the mean percentage of cells containing Th1 cytokines was significantly increased in the SFMC compared with the PBMC; no differences were found in the mean percentage of IL-4-containing cells. A comparable shift toward Th1 cytokines was observed when the amount of secreted cytokine was determined by ELISA.

CONCLUSION

A shift toward T cells with a Th1 cytokine profile was observed in the joints of patients with RA. Since an imbalance between Th1 and Th2 cells is thought to be of pathogenic significance, this finding might have implications for the development of new therapies for RA.

Human keratinocytes constitutively express IL-4 receptor molecules and respond to IL-4 with an increase in B7/BB1 expression

In certain pathological conditions, such as atopic dermatitis, interleukin-4 (IL-4) can be detected in the skin. As the role of this cytokine in inflammatory skin lesions is not completely clear, we investigated its biological effects on skin keratinocytes. It was found that freshly isolated as well as cultured keratinocytes obtained from normal individuals express mRNA for the IL-4 receptor (IL-4R) and produce IL-4R protein, as determined by flow cytometry. Moreover, IL-4 induced a proliferative response in keratinocytes after 1 day of culture and enhanced B7/BB1 expression in these cells. B7-2 (CD86) mRNA and protein were neither detected on untreated nor IL-4 treated keratinocytes. In contrast to interferon-gamma (IFN-gamma), IL-4 did not induce ICAM-1 (CD54) or HLA-DR-expression. Keratinocytes which had been treated with IL-4 showed an enhanced ability to stimulate allogeneic T-cell proliferation in the presence of staphylococcus enterotoxin B (SEB), (p < 0.01). Neutralizing anti-B7/BB1 monoclonal antibodies did not block this effect. These results indicate that other molecules than B7/BB-1. HLA-DR or ICAM-1 on IL-4-activated keratinocytes may be involved in T-cell stimulation. In conclusion our results suggest that locally produced IL-4, besides modulating keratinocyte membrane molecules, may enable keratinocytes to interact with skin infiltrating lymphocytes.

A strict requirement of interleukin-4 for interleukin-4 induction in antigen-stimulated human memory T cells

The role of interleukin-4 (IL-4) in the induction of IL-4 in mouse T cells is well established, but conflicting results have been reported with anti-CD3-primed human T cells and T cell clones. Therefore, IL-4 regulation was investigated in short-term cultured human T cells primed in vitro with either a superantigen or a hapten, nickel sulfate (NiSO4), for 3 days and expanded with IL-2 for another 5 days. Under these conditions, antigen-specific IL-4 producing T cells were generated in 35/40 cultures. Priming for IL-4 production was abrogated in all cultures by anti-IL-4 antibody or soluble IL-4 receptor (sIL-4R). Primed T cells that were IL-4- when cultured with IL-2 only developed an IL-4 producing phenotype when primed and expanded in the presence of exogenous IL-4. T cells primed in the presence of either endogenous or exogenous IL-4 produced 10-200-fold more IL-4 than T cells primed in the presence of anti-IL-4 antibody or sIL-4R. While IL-4 induction was absolutely dependent on IL-4, neither endogenous nor exogenous IL-4 influenced IFN-gamma synthesis. Most importantly, IL-4 induced and sIL-4R abolished priming for IL-4 production even in NiSO4-specific memory T cells from sensitized individuals. Thus, IL-4 induction in antigen-specific human memory T cell populations absolutely required IL-4. The IL-4 pathway of memory T cells retained a remarkable plasticity in sensitized individuals.

Differentiation and stability of T helper 1 and 2 cells derived from naive human neonatal CD4+ T cells, analyzed at the single-cell level

The development of CD4+ T helper (Th) type 1 and 2 cells is essential for the eradication of pathogens, but can also be responsible for various pathological disorders. Therefore, modulation of Th cell differentiation may have clinical utility in the treatment of human disease. Here, we show that interleukin (IL) 12 and IL-4 directly induce human neonatal CD4- T cells, activated via CD3 and CD28, to differentiate into Th1 and Th2 subsets. In contrast, IL-13, which shares many biological activities with IL-4, failed to induce T cell differentiation, consistent with the observation that human T cells do not express IL-13 receptors. Both the IL-12-induced Th1 subset and the IL-4-induced Th2 subset produce large quantities of IL-10, confirming that human IL-10 is not a typical human Th2 cytokine. Interestingly, IL-4-driven Th2 cell differentiation was completely prevented by an IL-4 mutant protein (IL-4.Y124D), indicating that this molecule acts as a strong IL-4 receptor antagonist. Analysis of single T cells producing interferon gamma or IL-4 revealed that induction of Th1 cell differentiation occurred rapidly and required only 4 d of priming of the neonatal CD4+ T cells in the presence of IL-12. The IL-12-induced Th1 cell phenotype was stable and was not significantly affected when repeatedly stimulated in the presence of recombinant IL-4. In contrast, the differentiation of Th2 cells occurred slowly and required not only 6 d of priming, but also additional restimulation of the primed CD4+ T cells in the presence of IL-4. Moreover, IL-4-induced Th2 cell phenotypes were not stable and could rapidly be reverted into a population predominantly containing Th0 and Th1 cells, after a single restimulation in the presence of IL-12. The observed differences in stability of IL-12- and IL-4-induced human Th1 and Th2 subsets, respectively, may have implications for cytokine-based therapies of chronic disease.

Simultaneous detection of cytokine and immunophenotype at the single cell level by immunoenzymatic double staining

The goal of this study was to establish a generally applicable immunoenzymatic method for the simultaneous detection of cytokine and immunophenotype at the single cell level. Evaluating various cell preparations and staining protocols, we found that permeabilization by saponin (0.1%) is very efficient, in combination with glutaraldehyde (0.04%) as fixative. Among various staining procedures, sequential immunoperoxidase labelling of the cytokine by use of diaminobenzidine, and detection of the immunophenotype by use of 4-chloronaphthol proved most discriminative. The typical localization of the cytokine reaction product ('Golgi staining') within the cell, and the 'ring-like' staining for the immunophenotype on the cell surface, allowed precise identification of double-labelled cells. Primary monoclonal antibodies from the same species could be used without loss of sensitivity and specificity for either or both antigens. This method thus provides the opportunity to study morphology, cytokine and immunophenotype simultaneously at the single cell level with standard equipment. Its application for the analysis of tissue samples is in progress, and may allow us to incorporate the cytokine-type as a new parameter in histopathological diagnostics.

Different cytokine patterns in bronchial biopsies in asthma and chronic bronchitis

Bronchial biopsies have made possible the detailed study of the pathology of the airways of humans with respiratory disease. Much data has been accumulated on asthmatics or normal controls but much less is known about chronic bronchitics. The aim of this study was to characterize the cellular and cytokine pattern seen in chronic bronchitics and to compare these with control and asthmatic subjects. The patients were also characterized clinically. In this study, immunocytochemistry on cryostat sections from bronchial biopsies were used to determine the level of inflammatory cells and cells of the immune system as well as the pattern of cytokines. This study revealed a distinct cellular and cytokine pattern for each of the three different patient groups, although the diversity of the cytokines analysed was limited by the size of the biopsies. In the inflammatory infiltrate of patients with asthma, CD4+ T-cells and eosinophils were the most prominent cell types discerned. All of the expected cytokines such as IL-1, TNF-alpha, IL-4, IL-5 and IFN-gamma were found. In contrast, the emphasis in chronic bronchitic patients was quite different. The predominant cell types were macrophages, neutrophils, mast cells and CD8+ T-cells, but eosinophils were also abundant. In addition, IL-4 and TNF-alpha were the only cytokines present of those tested.

Specific expression of surface interferon-gamma on interferon-gamma producing T cells from mouse and man

Interferon (IFN)-gamma is a potent immunoregulatory protein secreted by CD4+ and CD8+ T cells and by natural killer cells. Here, we show that IFN-gamma is specifically displayed at a low concentration on the cell surface of those activated T cells from mouse and man which express IFN-gamma. It is transiently expressed on the cell surface with kinetics similar to those of intracellular IFN-gamma expression. Detectable surface IFN-gamma is not expressed by activated T helper (Th) cells producing other cytokines but which do not express IFN-gamma. Thus, surface IFN-gamma is the first available marker for live T lymphocytes expressing IFN-gamma, e.g. Th1 cells.

Detection of intracytoplasmic cytokine using flow cytometry and directly conjugated anti-cytokine antibodies

Recently, there have been several reports demonstrating improvements in the flow cytometric detection of intracellular cytokines. These advances, although significant, have not yielded techniques that have easily been translated into broad use. To address this issue, we have coupled a fixation and permeabilization method with the use of directly labelled monoclonal anti-cytokine antibodies, providing both improved signal and simpler staining. The kinetics of in situ cytokine production in both CD4 and CD8 cells are shown for IL-2, IL-4, IL-5 and IFN-gamma. Based on these data, 6 h was chosen for optimal detection of this combination of cytokines. We show the specificity of this technique by blocking cytokine staining using a molar excess of recombinant cytokine. Additionally, unlabelled anti-cytokine antibodies are demonstrated to block specific staining of labelled antibody, providing an objective means to place statistical markers. Using such controls, we routinely detected as few as 0.1% false positive cells, allowing the flow cytometric detection of IL-5, which is below the threshold of detection of published methods. To further prove the specificity of staining, we stained using two anti-IL-5 mAbs known to recognize different epitopes and demonstrate that the same cells stain with both antibodies. Without permeabilization we could detect a fraction of cells with low intensity staining for cytokine. This staining was further examined using differential two color staining for intracellular and extracellular cytokine, clearly demonstrating no cells staining exclusively for extracellular cytokine, confirming a lack of passive transfer of cytokine to nearby cells. We show that cytokine flow cytometry is useful in examining the increased IL-5 production characteristic of eosinophilic states and that IL-5 production is limited to the CD27 negative subpopulation. These data illustrate the unique capability of cytokine flow cytometry to correlate cytokine expression with cell surface phenotype without cell separation. In summary, using directly conjugated anti-cytokine antibodies, cytokine flow cytometry becomes a specific and versatile technique for the assessment of complex cytokine production phenotypes in fresh ex vivo T cell subpopulations.

Heterogeneity of intracellular cytokine synthesis at the single-cell level in polarized T helper 1 and T helper 2 populations

CD4+ T helper (Th) cells can be classified into different types based on their cytokine profile. Cells with these polarized patterns of cytokine production have been termed Th1 and Th2, and can be distinguished functionally by the production of IFN-gamma and IL-4, respectively. These phenotypes are crucial in determining the type of immune response that develops after antigen priming. There are no surface markers that define them, and cytokine immunoassay or mRNA analysis both have limitations for characterization of single cells. Using immunofluorescent detection of intracellular IFN-gamma and IL-4, we have studied the emergence of Th1 and Th2 cells in response to antigen exposure and the patterns of cytokine synthesis in established T cell clones. IFN-gamma production by Th1 clones was detectable in almost all cells by 4 h, and it continued in most cells for > 24 h. IL-4 production in Th2 cells peaked at 4 h, but declined rapidly. In Th0 cells containing both cytokines, fewer cells produced IFN-gamma, which did not appear until IL-4 synthesis declined. Cocultivation of clones showed no such cross-regulation. Antigen stimulation of transgenic T cells expressing an ovalbumin-specific T cell receptor generated Th2 cells, probably as a result of endogenous IL-4 production. Addition of IL-12 and/or anti-IL-4 caused Th1 cells to develop, while some Th0 cells were seen when IL-12 alone was added. These results show that stimulation in the presence of polarizing stimuli results in cells producing either IFN-gamma or IL-4, but that coproduction can occur in rare cells under defined conditions.

Interleukin 4 (IL-4) and IL-6-producing memory T-cells in peripheral blood and gingival tissue in periodontitis patients with high serum antibody titers to Porphyromonas gingivalis

We assessed cytokine production and proliferation of memory T-cells that were isolated from peripheral blood of adult periodontitis patients with high anti-Porphyromonas gingivalis titer. Memory T-cells were stimulated with P. gingivalis lipopolysaccharide, sonicates and formalin-killed whole cells. Interleukin 4(IL-4)- and IL-6-producing cells were stained by immunocytochemistry on peripheral blood smears and compared with cryostat sections of autologous gingival biopsies. Memory T-cells in the peripheral blood of patients rated significantly higher than in healthy subjects (32.3 + or - 7.1 vs 25.3 + or - 3.0%). Stimulation of patient-derived memory T-cells with P. gingivalis whole cells induced higher IL-4 production than in healthy subjects (4.4 + or - 4.1% vs 0.7 + or - 0.6%). Induction of IL-4 producing memory T-cells by P. gingivalis lipopolysaccharide and whole cells was respectively 1.37 and 1.56 times that induced by medium alone. IL-6 production did not differ between the groups. Proliferation of memory T-cells in healthy subjects tended to be more inhibited by P. gingivalis antigens than that in patients. In some patients, induction of IL-4- and IL-6-producing memory T-cells in peripheral blood and in autologous gingival biopsies tended to coincide. Memory T-cells with functional characteristics of Th2 could be a crucial cell population capable of reflecting individual susceptibility to periodontitis.

Cytokine profiles of Porphyromonas gingivalis-reactive T lymphocyte line and clones derived from P. gingivalis-infected subjects

Porphyromonas gingivalis is generally recognized as a major periodontopathogen such that a study of T cell responses to this organism may help to elucidate immune regulation in periodontal disease.

OBJECTIVE

The aim of this study was to examine interleukin (IL)-4, interferon (IFN)-gamma and IL-10 production by P. gingivalis-responsive T cell lines and clones derived from the peripheral blood of two P. gingivalis-infected subjects with different disease expression and from the gingival tissues of one of the P. gingivalis-infected subjects.

MATERIALS AND METHODS

FACS analysis was used to determine the percentage of T cells staining positive for cytoplasmic IL-4, IFN-gamma and IL-10 and reverse transcriptase polymerase chain reaction (RT-PCR) was performed to determine the presence of mRNA for IL-4 and IFN-gamma in the T cell lines and clones.

RESULTS

FACS analysis showed that virtually all the T cell lines and clones contained IL-4- and IFN-gamma-producing T cells. The RT-PCR results generally supported this trend. However, a higher percentage of cells in the clones derived from one subject produced IL-4 while a lower percentage produced IFN-gamma compared with the clones derived from the other subject. FACS analysis also demonstrated that the lines and clones derived from the two subjects showed differences in IL-10 production.

CONCLUSION

This study has demonstrated that there may be differences in IL-4 and IL-10 production by the P. gingivalis responsive lines and clones derived from P. gingivalis-infected subjects with different disease expression. Any relationship to disease however, remains to be determined.

Interleukin-4 and interleukin-5 are rarely co-expressed by human T cells

Interleukin (IL)-4 and IL-5 are two cytokines which synergize in the induction of several biological effector functions. They are produced by mouse and human T helper 2 (Th2) and T helper 0 (Th0) cells. Little is known about the regulation of the two cytokines at the single-cell level. Here we show, using a flow cytometric intracellular staining technique, that IL-4 and IL-5 are predominantly produced by different human peripheral CD4+ and CD8+ T cells, whereas interferon (IFN)-gamma and IL-2 are produced by the same cells. In contrast, cloned human Th0 and Th2 cells were able to produce IL-4 and IL-5 simultaneously. The segregation of IL-4 and IL-5 in activated peripheral T cells was found within 72 h of activation upon anti-CD3 or phorbol ester + ionomycin stimulation. The kinetics of IL-4 and IL-5 production were different at the mRNA and the intra- and extracellular protein level, indicating that the cytokines are regulated differently. T cells from three patients with hyper-IgE syndrome did not display a substantial proportion of IL-4/IL-5 double-positive cells. However, simultaneous production could be induced in normal human T cells after prolonged stimulation with a minimum of two restimulation cycles. We conclude that the simultaneous production of IL-4 and IL-5 is a feature of repetitively activated human T cells.

Effects of "systemic" budesonide concentrations on in vitro allergen-induced activation of blood mononuclear cells isolated from asthmatic patients

Blood levels of inhaled corticosteroids are significantly lower than those measured in the lung, but their concentration could still have anti-inflammatory effects. To determine whether budesonide, at concentrations similar to those obtained in blood after drug inhalation (10(-9) M), could downregulate the allergen-induced activation of mononuclear cells, we studied 21 atopic patients, sensitized to Dermatophagoides pteronyssinus (Der p). On blood mononuclear cells, isolated from these patients, incubated with Der p allergen extract and with or without budesonide, we evaluated: 1) the proliferative response of T cells; 2) the expression of two surface activation markers, the HLA-DR antigens and the interleukin (IL)-2 receptors; and 3) the release of cytokines known to modulate the allergic processes. Allergen-induced T-cell proliferation was associated with increased HLA-DR antigen and IL-2 receptor expression (P < 0.001), and with increased release of IL-2, interferon-gamma (IFN-gamma), IL-1 beta, tumor necrosis factor-alpha (TNF-alpha), and granulocyte/macrophage colony-stimulating factor (GM-CSF). The addition of budesonide at the beginning of the cell cultures induced a dose-dependent inhibition of T-cell proliferation, still significant (P < 0.05) at the lowest concentrations tested (10(-9) and 10(-10) M). A significant inhibitory effect on T-cell proliferation was also present when budesonide (10(-9) M) was added to the cell cultures 3 or 5 days after the beginning of the cell cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistological analysis of T cell functional subsets in chronic inflammatory periodontal disease

IL-2, interferon-gamma (IFN-gamma), IL-4 and IL-6 producing T cells in periodontitis and gingivitis-affected human tissues were investigated by immunohistochemistry to clarify the relationship between T cell functional subsets and disease entity. Using alkaline-phosphatase anti-alkaline-phosphatase technique, the relative proportions of each cytokine-producing T cell were calculated in the crevicular 1/3, middle 1/3 and oral 1/3 areas selected in the connective tissue of sections. CD19:CD3 and CD4:CD8 ratios were determined on the serial sections. Compared with gingivitis tissues, the proportion of cytokine-producing cells in periodontitis-affected samples was higher overall in the crevicular 1/3 (P < 0.02). The middle 1/3 exhibited a higher percentage of cytokine-producing cells, except for IL-6-producing cells. Frequencies of cytokine-producing cells in the oral 1/3 did not differ. IL-4 was the prominent cytokine in periodontitis-affected tissues, with the highest proportion detected in the crevicular 1/3. The CD19:CD3 ratio was higher in periodontitis tissues irrespective of the location, indicating a B cell dominance in periodontitis lesions. Furthermore, a significant positive correlation between the proportion of IL-4-producing cells and the CD19:CD3 ratio was noted. The CD4:CD8 ratio consistently exceeded 2.0 in both periodontitis and gingivitis. These results suggest that immunoregulation of both periodontitis and gingivitis are T cell-dependent, but in periodontitis type 2 helper T cells predominate and thereby control B cell activation.

Ontogeny of IL4 production

There is evidence to suggest that the production of some cytokines in childhood is different to that in adults. The production of IL4 in PHA-stimulated PBMC cultures was examined in healthy neonates, children and adults to determine the ontogeny of IL4 production throughout childhood. In vitro IL4 production was found to be significantly reduced in neonates and children under 10 years of age as compared to adults, and to increase progressively with age. The mechanisms leading to reduced IL4 production in neonates were shown to be different to those in children, with a defect in signal transduction demonstrated for lymphocytes from neonates but not children < 10 years. The presence of an inhibitory factor in cord blood plasma was also noted. These age-dependent variations in IL4 production and response to stimulation with PMA/Ca may reflect differences in naive and memory T cell populations.

Immunolocalization of intracellular interleukin-4 in normal human peripheral blood basophils

The question as to whether other cell types apart from helper T lymphocytes are capable of producing interleukin-4 (IL-4) has gained much interest over the last years. Recent studies indicate that human basophils also produce IL-4, although direct proof is missing so far. In this study we demonstrate the presence of IL-4 in the cytoplasm of in vitro activated human peripheral blood basophils derived from normal donors. Cytokine-producing cells were revealed at the single-cell level by intracellular immunofluorescence staining using IL-4-specific monoclonal antibodies. Basophils showed a characteristic, apparently granular staining pattern easily discerned from the eccentric dot-shaped staining pattern in activated T cells used in control experiments. Cell counts following priming with IL-3 and stimulation with polyclonal sheep anti-IgE antibody or the anaphylatoxin C5a revealed a significant increase in IL-4-positive basophils to about 19% as compared with unprimed, unstimulated control cells (6%). The amount of IL-4 in the supernatant of these cell preparations paralleled these observations with an at least five- to sevenfold increase following stimulation as compared with control cells (< 5 ng/ml). Using confocal scanning laser microscopy, the intracellular presence of IL-4 was confirmed, and the cells were identified as being basophils on terms of their characteristic multilobed nucleus. This observation was supported by double labeling studies using antibodies to IL-4 and to the high-affinity IgE receptor (Fc epsilon R1). Interestingly, stimulation of cells led to a decrease in the number of Fc epsilon R1-positive cells. The above results show direct evidence that IL-4 is produced by activated human basophils.

Early expression of cytokines in lymph nodes after treatment in vivo with Staphylococcus enterotoxin B

Excessive cytokine expression induced by superantigen may be one aspect of the pathophysiology associated with Gram positive bacteremia. We have undertaken a study of the kinetics of cytokine production in lymph nodes obtained from in vivo Staphylococcus enterotoxin B (SEB) treated animals. This study was designed to evaluate the short term cytokine profile observed using immunohistochemistry (IHC) in BALB/c mice injected intraperitoneally (i.p.). The observed immunohistochemical kinetic profiles were corroborated using reverse transcription-polymerase chain reaction (RT-PCR) RNA analysis. We report here that TNF, IL-2, and IFN-gamma are the principal cytokines which were detected within hours of SEB administration, and that other cytokines such as IL-3, IL-4, IL-5, IL-6, IL-10, GM-CSF and M-CSF were undetectable. TNF and IL-2 appeared very early following SEB priming, and were observed by 1 h. IFN-gamma which appeared later (maximally at 14 h) was produced predominantly by CD8+ cells. In contrast, the TNF and IL-2 were produced primarily by CD4+ cells. Identical results were obtained by IHC and RT-PCR; the kinetics of mRNA expression slightly preceded the appearance of protein. The TNF and IFN-gamma staining patterns observed in lymph node sections were indicative of Golgi-localized cytokine. The IL-2 staining pattern observed in lymph node sections was distinctive, covering a significant local area of cells. This local regional concentration of IL-2, which may result from cytokine attached to extracellular binding components, may be an important aspect of the activation phase of a developing immune response. Rapid induction and excessive cytokine production elicited by superantigen in vivo, may ultimately help to explain the shock and death associated with SEB.

IL-4- and IL-6-producing cells in human periodontal disease tissue

IL-4- and IL-6-producing cells in human periodontal disease tissues were investigated using immunohistochemical and in situ hybridization techniques. Immunohistochemical analysis demonstrated the presence of IL-4-producing cells within the CD45RO+ subset and the percentage of IL-4+ cells was significantly higher in periodontal lesions than in gingivitis tissues (p < 0.01). The percentage of IL-6-producing memory cells was higher in periodontal lesions compared with gingivitis tissues, although it was not statistically significant (p > 0.05). A reverse tendency in IL-4- and IL-6-positive cells was observed in a few individual cases. No IL-4 mRNA could be detected using the in situ hybridization technique. However, high levels of IL-6 mRNA were present in clinically healthy tissues, with a further increase in both epithelium and connective tissues affected by gingivitis, although only the former was significant (p < 0.025). There was a significant decrease in IL-6 mRNA in both the connective tissue (p < 0.025) and epithelium (p < 0.01) in periodontitis tissues compared with levels in gingivitis tissues. However, the levels of IL-6 mRNA in periodontal tissues were high compared with those of IL-1 mRNA, which was used in this study as a positive control. These results suggest that Th2-type cells may accumulate in periodontal lesions.

Role of cytokines in determining T-lymphocyte function

Early events in an immune response stimulate the production of cytokines that direct the subsequent development of T-helper (Th) subsets with discrete patterns of cytokine production. These events are dictated by the type of antigen/microorganism administered to a host, as well as dose and route of immunization. Bacterial stimuli activate macrophages of the innate immune response to produce IL-12 and drive Th1 development and cell-mediated immunity. Conversely, production of IL-4 early in an immune response favors a Th2 or allergic/humoral immune response. The ability of IL-4 and IL-10 to inhibit Th1 development and effector function, as well as the requirement of committed Th1 cells for co-stimulators to induce maximal IFN-gamma production, suggests that cell-mediated immunity is under strict control, probably to achieve immunity with minimum immunopathology.

Neutralizing monoclonal antibodies define two different functional sites in human interleukin-4

Human interleukin-4 (IL-4) is a small four-helix-bundle protein which is essential for organizing defense reactions against macroparasites, in particular helminths. Human IL-4 also appears to exert a pathophysiological role during various IgE-mediated allergic diseases. Seven different monoclonal antibodies neutralizing the activity of human IL-4 were studied in order to identify functionally important epitopes. A collection of 41 purified IL-4 variants was used to analyse how defined amino acid replacements affect binding affinity for each individual mAb. Specific amino acid positions could be assigned to four different epitopes. mAbs recognizing epitopes on helix A and/or C interfered with IL-4 receptor binding and thus inhibited IL-4 function. However, other mAbs also inhibiting IL-4 function recognized an epitope on helix D of IL-4 and did not inhibit IL-4 binding to the receptor protein. One mAb, recognizing N-terminal and C-terminal residues, partially competed for binding to the receptor. The results of these mAb epitope analyses confirm and extend previous data on the functional consequences of the amino acid replacements which showed that amino acid residues in helices A and C of IL-4 provide a binding site for the cloned IL-4 receptor and that a signalling site in helix D interacts with a further receptor protein.

Flow cytometric determination of cytokines in activated murine T helper lymphocytes: expression of interleukin-10 in interferon-gamma and in interleukin-4-expressing cells

In an immune response, effector functions are controlled by T helper (Th) 1 cytokines [interferon-gamma (IFN-gamma), interleukin (IL)-2 and tumor necrosis factor-beta] and Th2 cytokines (IL-4, IL-5 and IL-10). Here we analyze by multiparameter immunofluorescence to what extent IL-2, IL-4, IL-5, IL-10 and IFN-gamma are co-expressed in individual normal murine Th cells upon activation in vitro with the bacterial superantigen Staphylococcus aureus enterotoxin B, presented in the context of major histocompatibility complex class II. IL-2 and IFN-gamma are co-expressed by some, but not by other Th cells. Expression of IL-4 and IFN-gamma is exclusive. IL-10 is co-expressed in individual cells either with IL-4 or with IFN-gamma. No IL-5-expressing cells are detected. While IL-10- and IL-4-co-expressing Th cells correspond to classical Th 2 cells, cells co-expressing IL-10 and IFN-gamma could be involved in negative-feedback regulation of a Th1 response. Apart from such functional implications, our results show that IL-2, IL-4, IL-5, IL-10 and IFN-gamma are expressed independently of each other in individual murine Th cells.

The effect of anti-CD4 on helper function of CD4,45RA+ versus CD4,45RO+ T cells

Here we have investigated and compared the effects of anti-CD4 on helper function of CD4,45RA+ versus CD4,45RO+ T cells. Only CD4,45RO+ cells, but not CD4,45RA+ cells were able to promote B cell differentiation resulting in immunoglobulin production in vitro (IgM as well as IgG) which could be inhibited by anti-CD4 MoAbs (MAX.16H5 and T151). In pokeweed mitogen (PWM)-induced B cell proliferation a similar pattern of responsiveness was obtained. When we studied the anti-CD4 effects on cytokine production in T cells stimulated in mixed lymphocyte reaction (MLR) or by mitogens, we found that neither IL-2 nor IL-4 production was dramatically influenced by anti-CD4 in CD4,45RO+ cells. This led us to the conclusion that the inhibitory effect of anti-CD4 on B cell proliferation and immunoglobulin secretion was not due to inhibition of cytokine production. To clarify this point, we investigated the ability of anti-CD4 to inhibit conjugate formation between B and T cells. It was found that CD4,45RO+ T cells formed more conjugates than CD4,45RA+ cells, and that only the conjugate formation by CD4,45RO+ T cells was inhibited by anti-CD4. These results suggest that (i) anti-CD4 inhibits T helper functions primarily by affecting CD4,45RO+ cells, and (ii) this effect is probably mediated by contact inhibition in the early phase of T-B collaboration.

The mitogen-induced generation of interferon-gamma producing cells in cultures of rhesus monkey peripheral blood mononuclear cells is age-dependent

An enzyme-linked immunoabsorbent spot (ELISPOT) assay has been developed for measuring the frequency of interferon-gamma (IFN-gamma) producing cells in rhesus monkeys. Aged monkeys revealed, upon mitogenic stimulation, a significantly higher percentage of IFN-gamma secreting peripheral blood mononuclear cells (PBMC) compared to young animals. No correlation was found between the frequency of IFN-gamma producing PBMC and the mitogen-driven proliferation, indicating that in rhesus monkeys no direct correlation exists between these two activation parameters.

Similar frequencies and kinetics of cytokine producing cells in murine peripheral blood and spleen. Cytokine detection by immunoassay and intracellular immunostaining

Production of IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, IFN-gamma, GM-CSF (granulocyte-macrophage colony stimulating factor) and macrophage colony stimulating factor by murine peripheral blood and spleen cells was analyzed following primary and secondary mitogen stimulation in vitro. Individual cytokine producing cells were detected by an intracytoplasmic staining technique. Cytokine production in cells from peripheral blood and spleen was comparable and more rapidly induced by calcium ionophore and phorbol 12-myristate 13-acetate than by concanavaling A. Restimulation in vitro induced both a swift production of cytokines and, for some cytokines, higher frequencies of producing cells. This was especially evident for IL-10 secreting cells, which increased 30-80 times in secondary responses. These analyses using the dual approaches of immunoenzymetric and fluorescent immunohistochemical techniques provide important evidence that cytokine induction kinetics can differ following primary or secondary stimulation.

Interferon alpha increases the frequency of interferon gamma-producing human CD4+ T cells

An increased ratio of T helper type 2 (Th2)- vs Th1-like cells contributes to the immune dysregulation in allergic disease situations and in many chronic infections, including AIDS. Th2-type immune responses are characterized by Th cells that produce increased levels of interleukin-4 (IL-4) and decreased levels of interferon gamma (IFN-gamma). The induction of either a Th1- or a Th2-like phenotype may be critically controlled by the antigen-presenting cells and their cytokines, e.g., IFN-alpha. In this study we have determined the frequencies of potential IL-4- and/or IFN-gamma-producing T cells in the peripheral blood of randomly selected healthy individuals, and analyzed whether IFN-alpha controls IL-4 and/or IFN-gamma production. Purified CD4+ or CD8+ T cells were stimulated for 24 h via the T cell receptor/CD3 complex in the presence or absence of IFN-alpha, and single IL-4- and IFN-gamma-secreting cells were detected in enzyme-linked immunospot assays. In the absence of IFN-alpha, CD4 cells produced IFN-gamma at frequencies of 1:50-300, and produced IL-4 at frequencies of 1:110-<1:100,000. Addition of IFN-alpha during the activation of CD4 cells increased the levels of IFN-gamma mRNA. As a consequence, the numbers of IFN-gamma-producing CD4 cells and the amounts of secreted IFN-gamma increased 10-fold. In contrast, IFN-alpha did not increase the frequency of IL-4-secreting CD4 cells. In the absence of IFN-alpha, addition of exogenous IL-4 to cultures of CD4 cells suppressed IFN-gamma secretion by 70%. However, in the presence of IFN-alpha, IL-4 did not display any suppressive effect. Compared with CD4 cells, CD8 cells produced IFN-gamma more frequently (1:5-10) but IL-4 less frequently (1:5,300 to < 1:100,000). IFN-alpha did not display any effect on the frequency of either IFN-gamma or IL-4 production by CD8 cells. Taken together the results indicate that IFN-alpha increases the frequency of IFN-gamma-secreting CD4 Th cells and antagonizes the suppressive effect of IL-4 on IFN-gamma production. As a consequence, IFN-alpha may favor the induction and maintenance of Th1-like cells and thereby counteract Th2-driven allergic immune responses.

Interleukin-6 production by brain tissue and cultured astrocytes infected with Theiler's murine encephalomyelitis virus

Theiler's murine encephalomyelitis virus (TMEV) is known to interact with cells of the central nervous system (CNS). Here we report that, interestingly, it is a potent inductor of interleukin-6 (IL-6) in the CNS of infected animals and in pure cultures of astrocytes. Maximal IL-6 gene transcription in glial cells, as detected by bioassay and ELISA, was observed at 6 and 24 h after infection. Astrocytes from both SJL/J and Balb/c (strains of mice susceptible and resistant, respectively, to TMEV-induced demyelination) produced similar amounts of IL-6, measured in tissue culture supernatants. These results indicate that although an immunomodulatory effect can be exercised by IL-6 synthesized by astrocytes, it does not play a crucial role in immune-mediated demyelination induced by TMEV.