Interleukin-10 Down-Regulates Oxidative Metabolism and Antibody-Dependent Cellular Cytotoxicity of Human Neutrophils

The authors investigated the ability of interleukin-10 (IL-10) to modulate some constitutive or interferon-γ (IFN-γ)-enhanced activities of human neutrophils. An 18 h culture of neutrophils with IL-10 dose-dependently down-regulated their capacity to produce O₂⁻ and lucigenin-amplified chemiluminescence in response to n-formyl-methionyl-leucylphenyl-alanine (FMLP). Furthermore, treatment of neutrophils with IL-10 decreased in a dose-dependent fashion, their capacity to lyse antibody-coated sheep erythrocytes. Membrane expression of FcγRI, FcγRII, FcγRIII, CR1, CR3 and FcγR- and CR-mediated phagocytosis were not modified by the cytokine. Culture of neutrophils with IFN-γ (100 U/ml) did not modify their FcγR- and CR-mediated phagocytosis, but significantly up-regulated FcγRI and CR3 membrane expression as well as their oxidative metabolism and antibody-dependent cellular cytotoxicity (ADCC). When IL-10 and IFN-γ were added simultaneously to neutrophil culture, IL-10 dose-dependently reduced IFN-γ-induced increase of CR3 expression, O₂⁻ production (in response to both FMLP and phorbol 12-myristate 13-acetate, or PMA) and ADCC, but did not change FcγRI expression on phagocytes. These results demonstrate that IL-10 is a significant neutrophil deactivator and provide new information on the role of IL-10 in the regulation of neutrophil-mediated inflammatory processes.     

Schistosoma mansoni Egg-Primed ThO and Th2 Cells: Failure to Down-regulate IFN-γ Production Following In Vitro Culture

Schistosoma mansoni eggs induce a rapid and pronounced T_h response which, based on cytokine secretion patterns, at day 3 post priming is T_h0)-like and at day 10 is T_h2-like. To establish whether or not the day-3 cells have been programmed in vivo to develop into T_h2 cells, they were cultured for 7 days to become in vitro equivalents of day-10 in vivo cells. Following this culture period, the population was approximately 75% CD4⁺, 22% CD8⁺, 6% B220⁺ and capable of producing IL-2, IFN-γ, IL-4, -5 and -10 upon stimulation. This T_h0-like status was confirmed by the observations that in response to mitogen IL-4 and IFN-γ production are both CD4⁺ -cell dependent and that IFN-γ and IL-4 are produced concomitantly by single cells. These data suggest that T^hO cells persist in vivo , but are incapable of secreting IFN-γ at day 10 due loan inhibitory factor which does not develop or is labile in vitro . This concept is supported by ihc surprising observation that day-10 LN cells, which are T_h2-like immediately ex-vivo , rapidly gain the ability to secrete IFN-γ following a short period of culture.     

Rheumatoid Inflammatory T-Cell Clones express mostly Th1 but also Th2 and Mixed (Th0-Like) Cytokine Patterns

This study was performed in order to characterize whether T cells from rheumatoid synovial inflammation belong to the Th1- or Th2-like functional subsets. Cytokine production was studied in 26 CD4⁺αβ⁺ and 2 CD8⁺αβ T-cell clones from the synovial fluid, the synovial membrane and peripheral blood of 5 patients. Fifteen of the CD4⁺ clones were raised against various mycobacterial antigens and 11 CD4⁺ clones and 2 CD8⁺ clones were raised unspecifically using PHA and/or IL-2. The specificities of these clones are not known. In the mycobacterial antigen-specific group, all CD4⁺'αβ T-cell clones produced IFN-γ at high levels, while the production of IL-4 was generally absent or low (< 1 ng/ml), consistent with a Thl-like profile. Some of these clones, however, also produced various amounts of IL-10 which has been regarded as a Th2 product but can be produced also in lower amounts by Thi cells. One HSP-65-specific clone produced levels of IL-4 and IL-10 in the same order as that of IFN-γ, thus appearing to be Th0-like. Among the 11 unspecific CD4⁺ clones, 7 showed a Thl-like pattern but with lower levels of IFN-γ than the antigen-specific clones. However, three clones did not produce any IFN-γ activity but produced IL-4 and one of them also produced distinct amounts of IL-10, compatible with a Th2-like pattern. In addition, one of the clones also showed an almost equally strong IFN-γ and IL-4 production, thus most likely representing a Th0-like clone.     

Primary Stimulation of CD4+ Cells in the Presence of IL-4 or IFN-γ Alters the Frequencies of Cytokine-Producing Cells at Restimulation

The induction of specific effector functions in naive T cells may be directed by accessory signals during activation. These could be elicited through binding to cell surface molecules or through factors secreted by antigen-presenting cells or other simultaneously activated cells. We have investigated the influence of CD8⁺ cells and of exogenousiy added cytokines (interleukin (IL)-2, IL-4 and interferon (IFN)-γ) on the cylokine production in splenic CD4⁺ T cells. IL-2, IL-4, IL-5 and IFN-γ production in CD4⁺ cells was measured at the single cell level during primary mitogen stimulation in vitro in the presence or absence of factors or CD8⁺ cells. On day 5 the cells were restimulated with mitogen alone and analysed to evaluate the short-term development of cytokine-producing cells in such cultures. Preactivation in the presence of either exogenous IL-4 or IFN-γ led to an increased production of IL-4 and IFN-γ respectively at restimtilation, and the effects of both IL-4 and IFN-γ were augmented by IL-2. After preactivation in the presence of IL-2 and IL-4, every third CD4⁺ cell could be induced to produce IL-4. Exogenous IL-4 or IFN-γ further decreased each other's production. Depletion of CD8⁺ cells before activation resulted in a slight increase of IL-4-producing cells, indicating that simultaneous activation of CD8⁺ cells will influence lymphokine production in CD4⁺ cells. The results suggest that the pattern of lymphokines induced in naive cells may be influenced by factors secreted by preactivated CD4⁺ and CD8⁺ cells, and that naive cells are preferentially 'recruited' to produce similar cytokines.     

Interleukin-4 and Interferon-Gamma Production by Leishmania Stimulated Peripheral Blood Mononuclear Cells from Nonexposed Individuals

Interferon-gamma (IFN-γ) and interleukin-4 (IL-4) production by Leishmania reactive peripheral blood mononuclear cells (PBMC) from non-exposed individuals was investigated. IFN-γ was measured in culture supernatants after antigen stimulation. For the measurement of IL-4, antigen stimulated cells were pulsed with PMA and ionomycin before IL-4 release was measured. L. donovani and L. major antigens induced IL-4 production (105–1748pg/ml) in 13 and seven cultures, and IFN-γ production (1.7- > 66IU/ml) in 14 and 11 of 20 cultures, respectively. IL-4 production rose steeply after 6 days of antigen stimulation suggesting a response due to antigen recognition. Both IL-4 and IFN-γ production was abrogated by depletion of CD2⁺ or CD4⁺ but not CD8⁺ cells. CD2⁺ or CD4⁺ but not CD8⁺ enriched cultures produced cytokines as unseparated PBMC. Thus, in non-exposed individuals circulating Leishmania reactive CD4⁺ T cells could be demonstrated. The cells from different individuals showed different patterns of IFN-γ and/or IL-4 production upon antigenic stimulation. In experimental leishmaniasis the early balance between IFN-γ and IL-4 is important for the clinical outcome. Our findings call for studies of the importance of cytokine production by cross-reactive T cells for the outcome of L. donovani infections in humans and show that the method for IL-4 detection is useful for this purpose.     

Cytokine Gene Expression During Infeetion of Miee Lacking CD4 and/or CD8 with Trypanosoma cruzi

The expression of lymphokine genes during infection of virulent (Tulahuén) or mild ( CA-I ) strains of T. cruzi was studied in mice lacking CD4 and/or CD8 molecules. The increased susceptibility of CD4⁻ and CD4⁻ CD8⁻ mice to infection with CA-I or Tuiahuen was parallelled by diminished IFN-γ mRNA levels. Nitric oxide release and inducible nitric oxide synthase mRNA accumulation by cells from Tulahuen infected CD4⁻ mice was also diminished. CD8⁻ (but not CD4⁻ CD8⁻ mice) showed an increased IL-4 and IL-10 mRNA accumulation upon infection with both strains of T. cruzi. A T_h2-like' response (higher IL-4 and IL-10 mRNA to IFN-γ mRNA ratio), was also observed when cells from non-infected CD8 - mice were stimulated with T cell mitogens.     

Induction of Gut Mucosal Immune Responses: Importance of Genetic Background and Th1/Th2 Cross-Regulation

The reciprocal regulation of T-helper cell (Th) subsets is widely documented in various animal models of infectious diseases. In this study IFN-γ/IL-4 double knockout (DKO) mice were used to analyse the role of Th subsets in mucosal immune responses. We found that the DKO mice had normal IgA differentiation but impaired induction of specific gut mucosal antibody responses after oral immunization using cholera toxin adjuvant. Both Th1 and Th2 responses were reduced compared with wild-type mice. Despite the absence of both IFN-γ and IL-4 in the DKO mice the overall results were similar to previous observations in IFN-γ receptor-knockout (IFN-γR^−/−) mice and did not suggest a strict cross-regulation of the two Th subsets in the gut mucosa. To further examine the role of IFN-γ in mucosal immunity we compared two different mouse strains lacking IFN-γ, i.e. IFN-γ^−/− (C57BL/6) and IFN-γR^−/− mice (129/Sv). We found that IFN-γR^−/− mice exhibited reduced mucosal antibody responses and decreased Th1 and Th2 activity after oral immunization, while IFN-γ^−/− mice had intact antibody responses and increased Th2 responses. Thus, genetic differences were found to critically affect the development of a specific gut mucosal immune response. An enhanced Th2 activity in the Peyer's patches following oral immunization was associated with an ability to mount strong intestinal IgA immunity.     

Peripheral Immune Response in Pulmonary Tuberculosis

Cellular immune response and delayed-type hypersensitivity reactions are considered to play a major role in the immunopathogenesis of pulmonary tuberculosis (PTB). But the exact mechanism is still to be clarified. Th1 cells are mainly involved in cellular immune responses in PTB and provide a normal healing process with minimal or no sequela whereas Th2 cell and CD8⁺ T lymphocyte responses may lead to more severe type of disease. In this study, we investigated the peripheral blood immune responses in PTB. The study group consisted of acid fast positive young male soldiers with PTB and a negative HIV serology. The control group included healthy young volunteer male soldiers without a history of PTB. Intracytoplasmic cytokine content of CD8⁺ T cells and lymphocytes, including IL-2, IL-4, IL-5, IL-10 and IFN-γ were determined by flow cytometry, and IL-2, IL-4, IL-5, IL-10, IFN-γ and TNF-α serum levels were measured by cytometric bead array (CBA). No difference was observed between the percentages of T, B, NK cells and HLA-DR expression in both groups, however, the number of CD3⁺HLA-DR⁺ activated T cell percentages was higher in PTB group as compared to healthy subjects. IL-2, IL-4, IL-5, IL-10 contents of lymphocytes and IFN-γ⁺CD8⁺ T cells were found to be significantly lower in PTB patients when compared with healthy subjects, and in parallel, serum IL-2, IL-4, IL-5 and TNF-α levels were also significantly lower in PTB patients. In conclusion we suggest that, CD8⁺ T cells producing both Th1 and Th2 type cytokines, may play important role in the peripheral immune response to mycobacteria.     

Interleukin-6 is essential for Staphylococcal exotoxin B-induced T regulatory cell insufficiency in nasal polyps

Background The pathogenesis of nasal polyps is still unclear. There is increasing evidence indicating that Staphylococcal aureus (S. aureus) is associated with the formation of nasal polyps, but the mechanism has not been well documented to date.
Methods We stimulated cultured nasal polyps and turbinate tissues with Staphylococcal exotoxin B (SEB), detected the expression of pro-inflammatory cytokines (IL-2, IL-6, and IL-8) and T cell cytokines (IFN-γ, IL-4, IL-5, IL-10, and IL-17) in the supernatants, and evaluated mRNA expression (T-bet, GATA-3, Foxp3, and RORγt) and frequencies of CD4⁺CD25⁺ T regulatory cells (Tregs) in nasal tissues. We also evaluated the effects of blocking IL-6 with monoclonal antibodies to T cell profiles in cultured nasal tissues stimulated by SEB.
Results Levels of IL-6, IFN-γ and IL-4 increased significantly in SEB-stimulated nasal polyps. Meanwhile, mRNA expressions of T-bet and GATA-3 were significantly up-regulated, while Foxp3 was inhibited and the frequencies of CD4⁺CD25⁺ Tregs were decreased after SEB stimulation. After blocking IL-6, the levels of IL-10 and Foxp3 mRNA, as well as the frequencies of CD4⁺CD25⁺ Tregs, were significantly increased, while IFN-γ and IL-4 production and the mRNA expression of T-bet and GATA-3 were significantly inhibited.
Conclusions SEB is able to modulate pro-inflammatory factors, T-helper type 1/Th2 profiles and suppress Treg activity in cultured nasal polyps, which were rescued by blocking IL-6 activity. Therefore, IL-6 is essential for SEB-induced Treg insufficiency in nasal polyps.     

Lack of Polarized Type 1 or Type 2 Cytokine Profile in Asymptomatic HIV-1-Infected Patients During a Two-Year Bimonthly Follow-Up

The production of type 1 (interferon or IFN-γ) and type 2 (interleukin or IL-4 and IL-10) cytokines by mitogen-stimulated peripheral blood mononuclear cells (PBMCs) obtained from asymptomatic human immunodeficiency virus-seropositive (HIV⁺) patients untreated with any antiviral, antibacterial or antimycotic drugs, and from healthy individuals, was evaluated by quantitative ELISA. Patients who were HIV⁺ were characterized by the absence of abnormal cytokine production. The level of each cytokine differed among individuals in the same group with intersubject variations greater for HIV⁺ patients than for healthy individuals. The longitudinal evaluation of IFN-γ, IL-4 and IL-10 production showed intrasubject variations which were particularly marked in HIV⁺ patients. Accordingly, HIV⁺ patients and, to a lesser extent, healthy individuals were characterized by a wide spectrum of possible profiles, which were confined to type 0 phenotype. In HIV⁺ patients no correlation was found between each cytokine level and the number of CD4⁺ T cells, not even in those with a falling CD4⁺ T-cell count and clinical symptoms.     

Blood eosinophils and serum IgE as predictors for prognosis of interferongamma therapy in atopic dermatitis

Background Interferon-gamma (IFN-γ) therapy has been reported to be effective in atopic dermatitis. However, IFN-γ therapy in atopic dermatitis has not yet been well established, ln this study, immunologic variables were evaluated as predictors for the prognosis of IFN-γ therapy in atopic dermatitis
Methods Sixty-eight atopic dermatitis patients were each treated 18 times with 2 X 10⁶ units/m² IFN-γ. Blood IgE level, eosinophil percentage, eosinophil count, and levels of IFN-γ, interIeukin-4 (IL-4), IL-5, and IL-10 were investigated. According to clinical responses, patients were classified into three groups: patients with improved clinical severity scores of over 20% were included in group A; those with improved scores of 20% or less in group B; and those with no improvement in group C.
Results Serum IgE levels and blood eosinophil percentages were the lowest n group A. Most atopic dermatitis patients with an eosinophil percentage over 9% and IgE level over 1500 lU/ml did not respond to IFN-γ therapy. Initial IL-10 levels were the highest in group A. IL-4 levels in group A, and IL-5 and IL-10 levels in all groups were significantly decreased by IFN-γ therapy.
Conciusions WN-y therapy may be recommended for atopic dermatitis patients with blood eosinophil percentages less than 9% and serum IgE levels less than 1500 lU/ml.     

Priming of T-Cell Responses in Mice by Porins of Salmonella typhimurium

An imbalance in signals delivered to T cells via T-cell receptor and accessory molecules can lead to anergy, apoptosis, or both. In the present study we have demonstrated that Salmonella typhimurium infection in mice leads to a progressive loss of CD4⁺ T helper (Th) cell population, abnormal T-cell death by apoptosis and loss of accessory molecules (B7 and intracellular adhesion molecule-1) on macrophages. Quantification of interleukin-2 (IL-2), interleukin-4 (IL-4) and interferon-γ (IFN-γ) secretion revealed a Th2-type of response in lymphocytes isolated from spleen. However, preimmunization of mice with porins resulted in an increased CD4⁺ Th cell population and accessory molecules on the surface of macrophages. Quantification of cytokines revealed a Th1-type of response. We conclude that preimmunization of mice with porins provides a microenvironment in which a well-balanced accessory molecule and cytokine network is established, which results in the prevention of cell death by apoptosis.     

Phenotypic and Functional Analysis of Activated B Cells of Autoimmune NZB × NZW F1 Mice

Polyclonal B-cell activation is the central theme in the production of autoantibodies and possible activation of autoreactive T cells in both human and murine lupus. The abnormal expansion of CD5⁺ B cells in murine lupus has been suggested, in particular, to be one of the most characteristic findings in these mice. Activated B cells can be separated from the B cells of resting stage by the difference in cell density. The aim of this study was to investigate the characteristics of different densities of the spleen cells separated by gradient density. Furthermore, the ability of anti-DNA antibody secretion in each percoll gradient fraction of B cells was also analysed. The results showed: a higher percentage of CD5⁺ B cells, which corresponded to the activated B-cell population, in percoll gradient 1 and 2 fractions; that splenic B cells of NZB/W F₁ mice had proliferative response to interleukin (IL)-4 or IL-5 but not to IL-10 or interferon-γ (IFN-γ); and that B cells isolated by percoll gradient produced anti-DNA antibody after stimulation with lipopolysaccharide (LPS) plus IL-5 and IFN-γ, but not IL-4 and IL-10. These data suggest that B cells at different stages of activation express differential characteristics and functions.     

Acquisition of Interleukin-5 Secretion by Human Naive T-Helper Cells is Regulated by Distinct Signals from both the T-Cell Receptor/CD3 Complex and CD2

We developed a human naive T-helper (Th) cell differentiation model with anti-CD3 monoclonal antibody (MoAb), using a B-cell line as source of costimulation. In this system, we examined the contribution of the T-cell receptor (TCR)/CD3-derived signals and that of lymphocyte function-associated antigen-1 (LFA-1) and CD2 in regulating Th-cell subset differentiation. We found that lowering the level of anti-CD3 MoAb decreased tumour necrosis factor-α (TNF-α) production, while increasing secretion of the Th2 cytokines, interleukin-5 (IL-5) and interleukin-13 (IL-13). Secretion of interferon-γ (IFN-γ) was not influenced by the strength of the anti-CD3 signal. Under conditions where Th0 cells are generated, co-culture with anti-CD2 F(ab')₂ MoAb led to the generation of Th cells that secreted 30–35% less IL-5, while not affecting secretion of IFN-γ or granulocyte–macrophage colony-stimulating factor (GM-CSF). By contrast, anti-CD18 MoAb F(ab')₂ inhibited IFN-γ and GM-CSF levels only in the primary stimulation, but did not affect cytokine levels after restimulation. Neither anti-CD2 nor anti-CD18 F(ab')₂ MoAbs could alter cytokine secretion profiles of peripheral blood-derived memory/effector Th cells. Our results indicate that acquisition of IL-5 secretion capability by Th cells is regulated mainly by signals transduced by the TCR/CD3 complex and by the presence of interleukin-4 (IL-4), while the CD2/LFA-3 pathway plays an additional, but minor, role. These regulatory CD2-derived signals, however, are distinct from those generated by the TCR/CD3 complex.     

Suppression of Experimental Autoimmune Myasthenia Gravis After CD8 Depletion is Associated with Decreased IFN-γ and IL-4

CDS⁺ T cells can perform both Th1 - and Th2-like functions by producing cytokines such as interferonγ (IFN-γ) and interleukin-4 (IL-4), as well as the immune response down-regulating transforming growth factor-β (TGF-β), which are all involved in the development of experimental autoimmune myasthenia gravis (EAMG), a model for human MG. We have reported that depletion of CD8⁺ T cells results in the suppression of EAMG accompanied by the down-regulation of AChR-specific B cell responses and AChR-reactive IFN-γ secreting Th1-like cells. To identify the involvement of IFN-γ, IL-4 and TGF-β in the development of EAMG after CD8⁺ T cell depletion, the expression of mRNA for these cytokines was studied in mononuclear cells from popliteal, inguinal and mesenteric lymph nodes, spleen and thymus by adopting in situ hybridization with complementary DNA oligonucleotide probes. Depletion of CD8⁺ T cells resulted in decreased levels of IFN-7 and IL-4 mRNA expressing cells in different lymphoid organs except thymus, but no change in the numbers of TGF-β mRNA expressing cells. The results imply that the suppression of EAMG after depletion of CD8⁺ T cells is caused by decreasing the effector factors but not by increasing the suppressor factor(s).     

Suppression of allergic inflammation by allergen-DNA-modified dendritic cells depends on the induction of Foxp3+ Regulatory T cells

CD4⁺CD25⁺Foxp3⁺Regulatory T cells (Tregs) play important roles in regulating allergic inflammation. To analyse if allergen-DNA-modified dendritic cells (DC) can suppress allergic responses and what roles Treg cells play in DC-based allergen-specific immunotherapy. Immature DC were transfected with retrovirus encoding Der p2 DNA, and administered to mice that sensitized and challenged with Der p2 protein. After Treg cells were depleted with anti-CD25 mAb, mice were re-challenged to observe the airway inflammation, and Treg cells in spleen CD4⁺ T cells. And responses of spleen CD4⁺ T cells to Der p2 were determined. Co-culture of naïve CD4⁺ T cells with allergen-modified DC induced Foxp3+ Tregs. Sensitized and challenged mice developed allergic airway inflammation and Th2 responses, and decreased Foxp3⁺ Tregs. Treatment with allergen-modified-DC suppressed airway inflammation and Th2 responses, and increased IL-10 and IFN-γ production and Foxp3⁺ Tregs significantly; and eliminated the responses of CD4⁺ T cells to allergen. Administration of anit-CD25 mAb eliminated all the effects of modified-DC except for the increasing of IFN-γ. Allergen-modified DC can induce immune tolerance to allergens and reverse the established Th2 responses induced by allergen, with dependence on the induction of Foxp3⁺ Tregs.     

Effect of H1-receptor antagonists on proliferative response, cytokine production, and cellular migration of human T cells and macrophages

Cytokine imbalance and cellular migration to inflammatory sites are critical components of allergic diseases. Redirecting cytokine imbalance and inhibiting cell migration therefore represent important therapeutic strategies for the treatment of these disorders. We studied the in vitro effect of the non-sedating H₁-receptor antagonists ebastine, carebastine, epinastine, cetirizine, and ketotifen on cytokine secretion by human T cells under various co-stimulatory conditions and the migratory activity of activated T cells as well as production of pro-inflammatory cytokines by macrophages. Ebastine and carebastine inhibited T cell proliferation and production of IL-4, IL-5, IL-6, and TNF-α by T cells under co-stimulation with CD28 plus CD3, CD26 plus CD3, and CD3 plus phorbol myristate acetate, whereas these drugs had no effect on the production of IL-2 and IFN-γ. Ebastine and carebastine also inhibited T cell migration and production of TNF-α and IL-6 by macrophages. Epinastine inhibited T cell proliferation and production of IL-2, IFN-γ, IL-4, and IL-5, whereas it elicited no effect on the production of IL-6 and TNF-α by T cells and macrophages as well as T cell migration. Cetirizine and ketotifen had no effects on cytokine production and T cell migration. Our results suggest that certain H₁-receptor antagonists, most notably ebastine and carebastine, can influence T cell migration and cytokine production in addition to antagonizing the H₁ receptor. These drugs therefore might be useful against T cell-mediated allergic inflammatory disorders such as asthma, atopic dermatitis, and psoriasis.     

Contrary Roles of IL-4 and IL-12 on IL-10 Production and Proliferation of Human Tumour Reactive T Cells

The cytokine profile of tumour reactive T cells is likely to play a central role in their function. However, little is known about how cytokine patterns of tumour reactive T cells can be regulated. Here, the authors investigated the influence of exogenous regulatory cytokines in addition to interleukin-2 (IL-2) on cytokine patterns and the proliferation of T cells recognizing an autologous sarcoma cell line. In this system, IL-4 and IL-12 showed the most polarizing influences on tumour reactive T cells. Exogenous IL-4 induced a predominant production of IL-4 while decreasing the interferon-γ (IFN-γ) and IL-10 production by tumour reactive T cells. It also stimulated the growth of tumour reactive CD4⁺ T cell clones. In contrast, IL-12 substantially increased the production of IL-10 and IFN-γ. This was accompanied by a growth inhibition of tumour reactive T cells. The growth of CD4⁺ tumour reactive T cells was also suppressed by exogenous IL-10. This study shows that cytokine patterns and proliferation tumour reactive T cells can be significantly influenced by exogenous cytokines and confirms the hypothesis of a negative feedback loop of IL-12 by the induction of IL-10 in the context of human tumour reactive T cells.     

Downregulation of CXCR6 and CXCR3 in lymphocytes from birch-allergic patients

Preferential expression of chemokine receptors on Th1 or Th2 T-helper cells has mostly been studied in cell lines generated in vitro or in animal models; however, results are less well characterized in humans. We determined T-cell responses through chemokine receptor expression on lymphocytes, and cytokine secretion in plasma from birch-allergic and healthy subjects. The expression of CCR2, CCR3, CCR4, CCR5, CCR7, CXCR3, CXCR4, CXCR6, IL-12 and IL-18R receptors was studied on CD4⁺ and CD8⁺ cells from birch-allergic ( n  = 14) and healthy ( n  = 14) subjects by flow cytometry. The concentration of IL-4, IL-5, IL-10, IL-12, IFN-γ and TNF-α cytokines was measured in plasma from the same individuals using a cytometric bead array human cytokines kit. The similar expression of CCR4 in T cells from atopic and healthy individuals argues against the use of the receptor as an in vivo marker of Th2 immune responses. Reduced percentages of CD4⁺ cells expressing IL-18R, CXCR6 and CXCR3 were found in the same group of samples. TNF-α, IFN-γ, IL-10, IL-5, IL-4 and IL-12 cytokines were elevated in samples from allergic individuals. Reduced expression of Th1-associated chemokine receptors together with higher levels of Th1, Th2 and anti-inflammatory cytokines in samples from allergic patients indicate that immune responses in peripheral blood in atopic diseases are complex and cannot be simplified to the Th1/Th2 paradigm. Not only the clinical picture of atopic diseases but also the clinical state at different time points of the disease might influence the results of studies including immunological markers associated with Th1- or Th2-type immune responses.     

Cytokines and PGE2 Modulate the Phagocytic Function of the β-Glucan Receptor in Macrophages

Under serum-free conditions the β-glucan receptor of mouse macrophages mediates phagocytosis of β-l,3-D-glucan-coated microbeads (diameter 2 μm). IFN-γ increases the phagocytic function of the β-glucan receptor in a dose-dependent manner, giving the plateau level at 100 U/ml. Maximum activity appears 9 h after addition of IFN-γ to the cells. The effect disappears within 24 h. The effect of IFN-γ may be a result of augmented receptor synthesis since treatment with cycloheximide reduces the phagocytosis.
IL-1 also increases the phagocytic function of the β-glucan receptor giving a dose-dependent response and with the plateau level reached at 10 U/ml. Maximum activity is found 4 h after addition of IL-I to macrophages. The effect disappears within 24 h. TNF does not alter the phagocytic function of the β-glucan receptor, but TNF together with IL-1 prolongs the effect of IL-1.
PGE₂ reduces the phagocytic function of the β-glucan receptor. Maximum reduction is achieved with 8 ng/ml. Time-course studies show the lowest phagocytic activity 9 h after addition of PGE₂ to the cells.