Pattern Of Cytokine Production Research Articles

Extensive characterization of the immunophenotype and pattern of cytokine production by distinct subpopulations of normal human peripheral blood MHC II+/lineage− cells

Dendritic cells (DC) represent the most powerful professional antigen-presenting cells (APC) in the immune system. The aim of the present study was to analyse, on a single-cell basis by multiparametric flow cytometry with simultaneous four-colour staining and a two-step acquisition procedure, the immunophenotypic profile and cytokine production of DC from 67 normal whole peripheral blood (PB) samples. Two clearly different subsets of HLA-II+/lineage- were identified on the basis of their distinct phenotypic characteristics: one DC subset was CD33strong+ and CD123dim+ (0.16 +/- 0.06% of the PB nucleated cells and 55.9 +/- 11. 9% of all PB DC) and the other, CD33dim+ and CD123strong+ (0.12 +/- 0.04% of PB nucleated cells and 44.53 +/- 11.5% of all PB DC). Moreover, the former DC subpopulation clearly showed higher expression of the CD13 myeloid-associated antigen, the CD29 and CD58 adhesion molecules, the CD2, CD5 and CD86 costimulatory molecules, the CD32 IgG receptor and the CD11c complement receptor. In addition, these cells showed stronger HLA-DR and HLA-DQ expression and a higher reactivity for the IL-6 receptor alpha-chain (CD126) and for CD38. In contrast, the CD123strong+/CD33dim+ DC showed a stronger reactivity for the CD4 and CD45RA molecules, whereas they did not express the CD58, CD5, CD11c and CD13 antigens. Regarding cytokine production, our results show that while the CD33strong+/CD123dim+ DC are able to produce significant amounts of inflammatory cytokines, such as IL-1beta (97 +/- 5% of positive cells), IL-6 (96 +/- 1.1% of positive cells), IL-12 (81.5 +/- 15.5% of positive cells) and tumour necrosis factor-alpha (TNF-alpha) (84 +/- 22.1% of positive cells) as well as chemokines such as IL-8 (99 +/- 1% of positive cells), the functional ability of the CD123strong+/CD33dim+ DC subset to produce cytokines under the same conditions was almost null. Our results therefore clearly show the presence of two distinct subsets of DC in normal human PB, which differ not only in their immunophenotype but also in their functionality, as regards cytokine production.

Effect of different sensitizing doses of antigen in a murine model of atopic asthma.

The dose of antigen is assumed to be one of the important factors in the polarized development of helper T cell subsets, i.e. Th1 or Th2 cells. We investigated the effect of the sensitizing antigen dose in a murine model of atopic asthma, which involved sensitization with ovalbumin (OVA) followed by repeated exposure to OVA aerosols. BALB/c mice were primed with varying doses of OVA (0, 10, 100 and 1000 microg) plus Al(OH)3 on days 0, 7 and 14, and were challenged with OVA aerosols (50 mg/ml for 20 min) on days 15-20. There were striking antigen dose-related differences in OVA-specific antibodies: high IgE and low IgG2a titres were found in mice sensitized at 10 microg, while low IgE and high IgG2a titres were seen at 1000 microg. The sensitizing dose was inversely correlated with the total cell count and the eosinophil count in bronchoalveolar lavage fluid (BALF), as well as with the extent of histological changes such as goblet cell hyperplasia of the bronchial epithelium and cellular infiltration into bronchovascular bundles. Antigen-induced bronchial hyper-responsiveness (BHR) to methacholine was observed with sensitization at 10 microg but not at 1000 microg. Splenic mononuclear cells (SMNC) obtained from mice sensitized at either dose showed proliferation in response to OVA. Production of IL-4 and IL-5 by OVA-stimulated SMNC was inversely correlated with the dose of sensitizing antigen. High-dose sensitization resulted in general suppression of cytokine production by SMNC, including interferon-gamma (IFN-gamma). The BALF levels of IL-4 and IL-5 were increased by low-dose sensitization, whereas IFN-gamma and IL-12 levels were increased by high-dose sensitization. These results suggest that the dose of sensitizing antigen defines the phenotypic changes in the present murine asthma model, presumably by influencing the pattern of cytokine production.

Evidence of dysregulated cytokine production by sinus lavage and peripheral blood mononuclear cells in patients with treatment-resistant chronic rhinosinusitis.

Treatment-resistant chronic rhinosinusitis (CRS) imposes a clinical challenge. Its pathogenesis may be associated with dysregulated immune/inflammatory responses in the sinus. To evaluate production of types 1 and 2 T cytokines (interferon gamma [IFN-gamma] and interleukin [IL] 5/IL-4, respectively) and regulatory/inflammatory cytokines (IL-10, IL-12, and IL-18) by sinus lavage (SL) cells and peripheral blood mononuclear cells (PBMCs) in patients with treatment-resistant CRS. Sample SL cells and PBMCs obtained from 19 patients with treatment-resistant CRS were cultured with or without stimuli, and cytokine levels in the supernatant were measured using enzyme-linked immunosorbent assay. Control PBMC samples were obtained from 26 children. Chronic otitis media was found in 15 patients. Neutrophils and/or epithelial cells were dominant in SL cells. IFN-gamma, IL-12p40, and IL-10 (>100 pg/mL) were detected in SL cell cultures from 12, 9, and 8 patients, respectively. Production of IL-12p40 and IL-18 by SL cells correlated positively with phytohemagglutinin and IL-12p70 stimuli. In 12 patients, we detected IL-18 (>100 pg/mL) in SL cell cultures without stimuli, whereas PBMCs produced little IL-18, irrespective of stimuli. There was no correlation between cytokine levels produced by SL cells and PBMCs, except for IL-12p40 produced using IL-18. Decreased IFN-gamma production by PBMCs was observed in 6 patients with CRS compared with controls, but 4 of them had elevated IFN-gamma production by SL cells. Production of IL-12p40 by PBMCs was higher in 10 patients with CRS than in controls, and 7 of these patients had lower IL-10 production, resulting in an increased IL-12p40/IL-10 ratio. There is a role for locally produced regulatory cytokines in IFN-gamma production in the sinus in patients with treatment-resistant CRS. However, aberrant cytokine production patterns by PBMCs can be detected at high frequency in these patients, indicating that this can be used as a prognostic marker for patients with CRS.

Cytokine pattern in postmenopause

Objective: The present study was undertaken to evaluate the pattern of serum cytokine production in postmenopausal women and the relationship with the hormonal status. A group of fertile women served as controls. Methods: Eighty-two women in apparent good health, non-smokers and without a history of hormone replacement therapy, were enrolled for the study. The women were divided in two groups according to their hormonal status: fertile women ( n=34, age 32±7 years) and postmenopausal women ( n=48, age 54±8 years). Blood samples were withdrawn in the morning, after an overnight fast. Results: Sex hormones (LH, FSH, Estradiol, Progesterone, DHEA, DHEA-S), as well as GH and IGF-1 levels, were significantly higher in the serum of fertile women as compared with their postmenopausal counterparts. Unlike IL-2, IL-4, IL-5, IL-10, IL-12 and IFN-γ, significant differences were observed in serum IL-6, IL-18, TNFα and TNFβ between groups: both IL-6 and IL-18 were higher in postmenopausal women, while TNFα and TNFβ were significantly lower. There was an inverse relationship between serum DHEA and DHEA-S levels and both IL-6 ( r=−0.46, P<0.02) or IL-18 ( r=−0.38, P<0.05) serum concentrations. Conclusions: Compared with fertile counterparts, women in postmenopause present an alteration in serum cytokine profile suggesting a prevalence of Th2 lymphocytes.

Reversal of human allergen-specific CRTH2+ TH2 cells by IL-12 or the PS-DSP30 oligodeoxynucleotide

Background: The chemoattractant receptor homologous molecule expressed on TH2 cells (CRTH2) is a receptor for prostaglandin D2, which among human T cells is selectively expressed by TH2 and type 2 cytotoxic effectors. Objective: Our purpose was to assess whether the cytokine production profile of TH2 effectors could be reversed by exploiting their selective expression of CRTH2. Methods: CRTH2+ T cells were purified from the blood of allergic subjects, stimulated with the specific allergen in the absence or presence of IL-12, and assessed by flow cytometry at the single-cell level for their ability to produce IL-4 and/or IFN-γ after antigen or polyclonal stimulation. Results: Both IL-12 and the PS-DSP30 oligodeoxynucleotide enabled CRTH2+ allergen-stimulated TH2 cells to produce IFN-γ. This change in the profile of cytokine production by TH2 cells from allergic subjects was related to the upregulation of IL-12 receptor β2 chain and was associated with the loss of CRTH2. Conclusions: These data demonstrate that the cytokine production pattern of fully differentiated TH2 effectors can be changed to a less polarized profile, thus providing the physiologic basis for new immunotherapeutic strategies in allergic disorders. (J Allergy Clin Immunol 2001;108:815-21.)

Bacterial Lipopolysaccharide Induces Transforming Growth Factor β and Hepatocyte Growth Factor through Tolllike Receptor 2 in Cultured Human Colon Cancer Cells

This study examined, in human cancer lines, the pattern of cytokine production stimulated by lipopolysaccharide (LPS), a major component of outer surface of gram-negative bacteria, and characterized the expression pattern of CD14, cell surface LPS receptor antigen, and toll-like receptors (TLRs), which appear to be key regulators of the innate immune response system. Two colon cancer cell lines (DLD and LoVo), a hepatocellular carcinoma cell line and a myelomonocytic cell line were incubated with LPS for 0-72 h, and transforming growth factor (TGF) beta1 and beta2, hepatocyte growth factor (HGF) and interleukins 6, 8 and 15 were assayed. The only changes induced by incubation with LPS were significant increases in TGFbeta1 production at 12 h, and in HGF production at 72 h, in LPS-stimulated DLD cells, and significant increases in TGFbeta2 production after 12 h and in HGF after 72 h in LoVo cells. Using reverse transcriptase-polymerase chain reaction analysis, expression of CD14 and TLR-2 mRNA was detected in DLD and LoVo cells, and expression of TLR-4 mRNA was detected in PLC/PRF/5 and KG-1 cells. These results suggest that LPS induces TGFbeta and HGF production mediated by CD14/TLR-2 in cultured human colon cancer cell lines.

Cytokine responses to mitogen and Schistosoma haematobium antigens are different in children with distinct infection histories.

Prevalence of Schistosoma haematobium infection in children from two neighbouring villages in Zimbabwe was 77.1% and 40.3%, respectively. The age-intensity data indicated peak intensities of infection at a lower age in the high prevalence village. This study investigated whether the difference in infection histories was reflected in a difference in cytokine profiles between children resident in these two villages. Blood samples were taken to assay for cytokine secretion 1 year after treatment for schistosomiasis. They were cultured with phytohaemagglutinin (PHA), schistosome egg antigens (SEA) or cultured without stimulant and tested for the presence of interleukin (IL)-4, IL-5, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-gamma. Blood samples from children from the low prevalence village were more likely to produce IL-4 (P < 0.0001) and produced higher levels of IFN-gamma (P < 0.02) and GM-CSF (P < 0.03) when cultured with PHA for 24 h. Residence in the high prevalence village was associated with production of IL-10 (P < 0.006) and GM-CSF (P < 0.04) in response to culture with SEA and IL-5 (P < 0.02) with PHA for 48 h. The interaction between age and village was not significant for these results; however, there was a significant interaction between age and village for IL-5 detected in blood samples cultured with PHA for 24 h (P < 0.01). These results concur with previous observations that major patterns of cytokine production can be related to immunosuppression, but also indicate an underlying pattern which reflects the importance of history of infection to the immune response.

Gestational attenuation of Lyme arthritis is mediated by progesterone and IL-4.

Infection of different strains of laboratory mice with the agent of Lyme disease, Borrelia burgdorferi, results in arthritis, the severity of which has been correlated with the dominance of Th1 cytokines. In this study, we demonstrate that changes in B. burgdorferi-specific immunologic responses associated with pregnancy can alter the outcome of Lyme arthritis in mice. Whereas nonpregnant female C3H mice consistently developed severe Lyme arthritis, pregnant mice had a marked reduction in arthritis severity that was associated with a slight reduction in IFN-gamma and markedly increased levels of IL-4 production by B. burgdorferi-specific T cells. Similar reductions in arthritis severity and patterns of cytokine production were observed in nonpregnant, progesterone-implanted mice. Ab neutralization of IL-4 in progesterone-implanted mice resulted in severe arthritis. Our results are consistent with the known shift toward Th2 cytokine expression at the maternal-fetal interface, and are the first to show a pregnancy-related therapeutic effect in an infectious model.

T-Cell immune activation in children with vertically transmitted hepatitis C virus infection.

Little is known concerning the clinical features, the histological outcome, and the effects on the maturation of immune system of children with vertically-transmitted hepatitis C virus (HCV) infection. Specifically, no data are available on the peripheral distribution of T-cell subsets. The frequency of naive and memory cells, activated T cells, and cytokine-producing T cells was analyzed in nine HCV-infected children born to HCV-positive mothers. In HCV-infected children, the distribution of naive and memory cells was not significantly altered in the CD4 subset whereas within the CD8 subset, an increase of memory and a decrease of naive cells was observed. The frequency of HLA-DR-positive and Fas-positive T cells was increased in HCV-infected children in both CD4 and CD8 subsets. The distribution of Fas-expressing T cells was directly related to that of HLA-DR cells and inversely related to the frequency of naive T cells. In regard with cytokine production we found increased levels of both CD4 and CD8 interferon-gamma (IFN-gamma)-producing cells whereas no difference in the percentage of interleukin-2 (IL-2)-producing T cells was observed. No meaningful correlation was observed between individual T cell subsets and ALT levels or HCV viral load. In conclusion, our results indicate an increased T-cell activation and a shift to a T(H)1 pattern of cytokine production in children with vertically transmitted HCV infection. The cause of this kind of immune response could reside in the persistent antigenic stimulation by chronic HCV infection.

Neuroendocrine regulation of autoimmune/inflammatory disease.

Interactions between the immune and nervous systems play an important role in modulating host susceptibility and resistance to inflammatory disease. Neuroendocrine regulation of inflammatory and immune responses and disease occurs at multiple levels: systemically, through the anti-inflammatory action of glucocorticoids released via hypothalamic-pituitary-adrenal axis stimulation; regionally, through production of glucocorticoids within and sympathetic innervation of immune organs such as the thymus; locally, at sites of inflammation. Estrogens also play an important role in immune modulation, and contribute to the approximately 2- to 10-fold higher incidence of autoimmune/inflammatory diseases seen in females of all mammalian species. During inflammation, cytokines from the periphery activate the central nervous system through multiple routes. This results in stimulation of the hypothalamic-pituitary-adrenal axis which, in turn through the immunosuppressive effects of the glucocorticoids, generally inhibits inflammation. Recent studies indicate that physiological levels of glucocorticoids are immunomodulatory rather than solely immunosuppressive, causing a shift in patterns of cytokine production from a TH1- to a TH2-type pattern. Interruptions of this loop at any level and through multiple mechanisms, whether genetic, or through surgical or pharmacological interventions, can render an inflammatory resistant host susceptible to inflammatory disease. Over-activation of this axis, as occurs during stress, can also affect severity of infectious disease through the immunosuppressive effects of the glucocorticoids. These interactions have been clearly demonstrated in many animal models, across species, strains and diseases, and are also relevant to human inflammatory, autoimmune and allergic illnesses, including rheumatoid arthritis, systemic lupus erythematosus, Sjogren's syndrome, allergic asthma and atopic skin disease. While many genes and environmental factors contribute to susceptibility and resistance to autoimmune/inflammatory diseases, a full understanding of the molecular effects on immune responses of combinations of neuropeptides, neurohormones and neurotransmitters at all levels has opened up new therapeutic approaches and are essential for the design of future therapies based on such principles.

Nutrition and the mucosal immune system.

Gut-associated lymphoid tissue is the dominant site for the initiation of mucosal immune response. Mucosal immunity depends on regulatory signals; nutritional elements, including fats, amino acids, and micronutrients, are critical cofactors for these signals. Nutrients specifically affect lymphocyte influx and migration, mononuclear cell activation, and the differentiated expression of immune response. The molecular basis of nutrient action has been shown to involve effects on receptor regulation, adhesion molecule expression, and the pattern of cytokine production. The gastrointestinal mucosal immune system is the major site for host interaction with microbes and provides a barrier against systemic access for food antigens and microbes. Nutrient metabolism has unique and direct impact on the host defense system of gut-associated lymphoid tissue and therefore has potential for widely disseminated impact on systemic immune response.

Defective antifungal T-helper 1 (TH1) immunity in a murine model of allogeneic T-cell–depleted bone marrow transplantation and its restoration by treatment with TH2 cytokine antagonists

Patients undergoing full haplotype-mismatched hematopoietic transplantations may experience severe intractable invasive fungal infections. To verify whether an imbalanced production of T-helper 1 (TH1) and TH2 cytokines may be responsible for susceptibility to fungal infections, C3H/HeJ (H-2(k)) recipient mice were lethally irradiated, received transplantations with T-cell-depleted allogeneic bone marrow (BM) cells from mice of H-2(d) haplotype, and were infected with Candida albicans. At different time-points after transplantation, mice were assessed for pattern of TH cytokine production and susceptibility to infection. The results show that a long-term, donor-type chimerism was achieved as early as 2 weeks after BM transplantation (BMT), at the time when high-level production of TH2 cytokines (interleukin-4 [IL-4] and IL-10) and impaired production of TH1 cytokines (interferon-gamma [IFN-gamma] and IL-12] were observed. At this time, mice were highly susceptible to both disseminated and mucosal infections, as indicated by decreased survival, uncontrolled fungal growth, and failure to develop protective TH1 immunity. However, a predominant production of TH1 cytokines was observed by week 5 after BMT, at the time when mice developed donor-type protective TH1 responses and were resistant to infections. Therapeutic ablation of IL-4 or IL-10 greatly increased resistance to candidiasis. These results indicate that a dysregulated production of TH cytokines occurs in mice undergoing T-cell-depleted allogeneic BMT. The transient predominant production of TH2 cytokines over that of IL-12 impaired the ability of mice to develop antifungal TH1 resistance, an activity that could be efficiently restored upon treatment with TH2 cytokine antagonists.

Elevated interleukin‐4 and interleukin‐13 production by T cell lines from patients with Churg‐Strauss syndrome

Objective To investigate cytokine production patterns of T cell lines (TCL) from patients with Churg-Strauss syndrome (CSS). Methods Short-term polyclonal TCL were generated from peripheral blood of patients with CSS or Wegener's granulomatosis (WG) and healthy controls (HC). TCL were established in the presence of interleukin-2 (IL-2) and phytohemagglutinin and were phenotypically characterized by flow cytometry. Th1/Th2 cytokine production by stimulated TCL (72 hours) was analyzed by enzyme-linked immunosorbent assay. Results TCL that represented the progeny of in vivo–activated T cells from CSS patients displayed a heterogeneous immunophenotype, with a predominance of CD4+ T cells when compared with WG TCL, which were predominantly CD8+. All CSS TCL shared the ability to produce large amounts of interferon-γ (IFNγ), IL-4, and IL-13 compared with HC (P = 0.014 for all 3). Production of IL-4 and IL-13 was higher in CSS TCL than in WG TCL (P = 0.014 for both). IL-5 production was up-regulated in WG TCL compared with CSS TCL (P = 0.014). Compared with HC, WG TCL showed increased production of IFNγ (P = 0.021), IL-5 (P = 0.043), and IL-13 (P = 0.021). Conclusion Our results indicate that, while there is evidence for both a type 1 and a type 2 response in CSS, type 2 cytokine production pattern appears to predominate in this disease when compared with WG and HC.

Vδ1T Lymphocytes Expressing a Th1 Phenotype Are the Major γδ T Cell Subset Infiltrating the Liver of HCV-infected Persons

Hepatitis C infection induces an acute and chronic liver inflammation that may lead to cirrhosis, liver failure, or hepatocarcinoma. Since the role of alphabeta T lymphocytes in hepatitis C virus (HCV) immunopathology has been analyzed extensively, we investigated the distribution and functional activation of gammadelta T cell subsets in chronically HCV-infected patients. Blood samples and liver biopsies from 35 patients with compensated chronic HCV infection were compared in terms of T cell subset distribution, expression of activation markers, gammadelta T cell receptor (TCR) repertoire, and pattern of cytokine production. Moreover, we analyzed whether these immunological parameters were associated with other clinical observations (plasma viremia, ALT levels, Ishak index). Differing from peripheral blood distribution, a specific compartmentalization of Vdelta1 T cells (p < 0.001) was observed in the liver of HCV patients. These cells represented a relevant fraction of intrahepatic T lymphocytes (1.8-8.7%) and expressed the memory/effector phenotype (CD62-L- CD45-RO+CD95+). This phenotype was consistent with selective homing upon antigen recognition. Mitogenic stimulation of Vdelta1 + T lymphocytes recruited in the liver revealed the T helper cell type 1 (Th1) pattern of cytokine secretion. Interestingly, the frequency of interferon-gamma (IFN-gamma)-producing Vdelta1 T cells was associated with an higher degree of liver necroinflammation, measured by the Ishak index. Finally, the T-cell repertoire analysis revealed the absence of Vgamma selection in the TCR repertoire of intrahepatic Vdelta1 T cells. gammadelta T cell distribution in the peripheral blood differs from the Vdelta1 T cell subset because it is policlonally activated and recruited in the liver of chronic HCV-infected patients. During HCV-infection, this T cell subset may release Th1 cytokines and contribute to the necroinflammatory liver disease.

Elevated interleukin-4 and interleukin-13 production by T cell lines from patients with Churg-Strauss syndrome.

To investigate cytokine production patterns of T cell lines (TCL) from patients with Churg-Strauss syndrome (CSS). Short-term polyclonal TCL were generated from peripheral blood of patients with CSS or Wegener's granulomatosis (WG) and healthy controls (HC). TCL were established in the presence of interleukin-2 (IL-2) and phytohemagglutinin and were phenotypically characterized by flow cytometry. Th1/ Th2 cytokine production by stimulated TCL (72 hours) was analyzed by enzyme-linked immunosorbent assay. TCL that represented the progeny of in vivo-activated T cells from CSS patients displayed a heterogeneous immunophenotype, with a predominance of CD4+ T cells when compared with WG TCL, which were predominantly CD8+. All CSS TCL shared the ability to produce large amounts of interferon-gamma (IFNgamma), IL-4, and IL-13 compared with HC (P = 0.014 for all 3). Production of IL-4 and IL-13 was higher in CSS TCL than in WG TCL (P = 0.014 for both). IL-5 production was up-regulated in WG TCL compared with CSS TCL (P = 0.014). Compared with HC, WG TCL showed increased production of IFNgamma (P = 0.021), IL-5 (P = 0.043), and IL-13 (P = 0.021). Our results indicate that, while there is evidence for both a type 1 and a type 2 response in CSS, type 2 cytokine production pattern appears to predominate in this disease when compared with WG and HC.

Protection and humoral immune responses against Bordetella pertussis infection in mice immunized with acellular or cellular pertussis immunogens

In the present study, protection against Bordetella pertussis infection and humoral immunological responses in mice has been assessed upon immunization with custom-made acellular pertussis vaccines (ACVs) and whole-cell pertussis vaccine (WCV). Mice were immunized, next intranasally infected with B. pertussis and during 14 days the number of bacteria in the trachea and lungs and the level of serum antibodies were determined. ACV contained five immunogens, filamentous hemagglutinin, pertactin, fimbriae serotypes 2 and 3, and chemically detoxified pertussis toxin (PMC-5), or three immunogens, filamentous hemagglutinin, pertactin, and genetically detoxified (BC-3) or chemically detoxified pertussis toxin (SKB-3). Immunization with a high or low dose of ACV or WCV resulted in significant protection against B. pertussis, with differences in the degree of protection between the vaccines. The lowest protection was found with a low dose of SKB-3 and WCV. The pattern of cytokine production by spleen cells of immunized, non-infected, mice indicated that T-helper 1 cells are activated by vaccination with WCV, and T-helper 1 and T-helper 2 cells are involved in the immune response upon vaccination with ACVs. Each vaccine stimulated the production of IgG, but not IgA, antibodies. In mice immunized with ACV, elimination of B. pertussis from trachea and lungs correlated significantly with the titre of IgG1, but not IgG2a, antibodies.

Le réseau des cytokines en situation normale et pathologique

Due to their pleiotropism and their ability to modulate somehow in a redundant manner the activity of a wide variety of cells, cytokines exhibit a surprising overlap in biological actions. Thus, one can define cytokine as a miscellaneous group of inducible, proteins or glycoproteins, which have no inherent activity and act as regulators of cell, tissue and organism function by binding with high affinity to specific cell-surface receptors. These receptors can be formed by a complex of multiple peptide chains linked to the membrane or they can be soluble receptors formed by the extracellular domains of the chains. Both types of receptors are potentially able to regulate the biologic fonction of the cytokine. Cytokines are modulators of the fonction of a lot of cell types and are implicated in the innate and specific immunity, in the proliferation, tissus differentiation and reparation. Therefore, the cytokine production pattern leads to complicated network of interactions, that render the description of a cytokine indissociable from the physiological context in which they exert their biologic activities. Cytokines produced by T lymphocytes are one of the key of the immune response in vivo and have lead to the definition of the Th-1 or Th-2 sub populations of T lymphocytes. The fonctional polarisation of immune responses towards a preferential Th-1 or Th-2 response is associated with a number of pathologic situations. In infectious pathologies, the Th-1 cell types are strongly implicated in the defense against intracellular agents, and the extracellular agents are better neutralized by a heterogeneous response that can be Th-1 or Th-2 oriented. During HIV infection, a deviation of the Th-1 response toward a Th-2 response can be seen and can be explained by the elevation of the response involving IL-4 and at the opposite a diminution of the reposnses involving IFNγ. In autoimmune diseases, the majority of the observed manifestations involve the participation of Th-1 type cytokines (IFNγ, IL-12) and Th-2 type cytokines (IL-10, IL-4). At the contrary, in allergic manifestations, allergen specific T cell clones are mostly the initiators of a Th-2 response. The quality of the immune response is tightly linked to a subtile inbalance between the Th-1 and Th-2 type of cytokines produced and most probably the development of a pathologic stage can be due more to a inappropriate immune response than to a insuffisant response.

Impaired gamma interferon responses against parvovirus B19 by recently infected children.

Parvovirus B19 is the causative agent of "fifth disease" of childhood. It has been implicated in a variety of conditions, including unsuccessful pregnancy and rheumatoid arthritis, and is a potential contaminant of blood products. There has been little study of immunity to parvovirus B19, and the exact nature of the protective humoral and cell-mediated immune response is unclear. Immune responses to purified virus capsid proteins, VP1 and VP2, were examined from a cohort of recently infected children and compared with responses from long-term convalescent volunteers. The results demonstrate that antibody reactivity is primarily maintained against conformational epitopes in VP1 and VP2. The unique region of VP1 appears to be a major target for cell-mediated immune responses, particularly in recently infected individuals. We confirm that antibody reactivity against linear epitopes of VP2 is lost shortly after infection but find no evidence of the proposed phenotypic switch in either the subclass of parvovirus B19-specific antibody or the pattern of cytokine production by antigen-specific T cells. The dominant subclass of specific antibody detected from both children and adults was immunoglobulin G1. No evidence was found for interleukin 4 (IL-4) or IL-5 production by isolated lymphocytes from children or adults. In contrast, lymphocytes from convalescent adults produced a typical type 1 response associated with high levels of IL-2 and gamma interferon (IFN-gamma). However, we observed a significant (P<0.001) deficit in the production of IFN-gamma in response to VP1 or VP2 from lymphocytes isolated from children. Taken together, these results imply that future parvovirus B19 vaccines designed for children will require the use of conformationally preserved capsid proteins incorporating Th1 driving adjuvants. Furthermore, these data suggest novel mechanisms whereby parvovirus B19 infection may contribute to rheumatoid arthritis and unsuccessful pregnancy.

Neuronal, astroglial and microglial cytokine expression after an excitotoxic lesion in the immature rat brain.

Cytokines are important intercellular messengers involved in neuron-glia interactions and in the microglial-astroglial crosstalk, modulating the glial response to brain injury and the lesion outcome. In this study, excitotoxic lesions were induced by the injection of N-methyl-D-aspartate in postnatal day 9 rats, and the cytokines interleukin-1 beta (IL-1beta), interleukin-6 (IL-6), tumour necrosis factor alpha (TNFalpha) and transforming growth factor beta 1 (TGF-beta1) analysed by ELISA and/or immunohistochemistry. Moreover, cytokine-expressing glial cells were identified by means of double labelling with glial fibrillary acidic protein or tomato lectin binding. Our results show that both neurons and glia were capable of cytokine expression following different patterns in the excitotoxically damaged area vs. the nondegenerating surrounding grey matter (SGM). Excitotoxically damaged neurons showed upregulation of IL-6 and downregulation of TNFalpha and TGF-beta1 before they degenerated. Moreover, in the SGM, an increased expression of neuronal IL-6, TNFalpha and TGF-beta1 was observed. A subpopulation of microglial cells, located in the SGM and showing IL-1beta and TNFalpha expression, were the earliest glial cells producing cytokines, at 2-10 h postinjection. Later on, cytokine-positive glial cells were found within the excitotoxically damaged area and the adjacent white matter: some reactive astrocytes expressed TNFalpha and IL-6, and microglia/macrophages showed mild IL-1beta and TGF-beta1. Finally, the expression of all cytokines was observed in the glial scar. As discussed, this pattern of cytokine production suggests their implication in the evolution of excitotoxic neuronal damage and the associated glial response.

CD8 depletion-induced late airway response is characterized by eosinophilia, increased eotaxin, and decreased IFN-gamma expression in rats.

There is an emerging body of knowledge defining the role of CD8(+) cells in the pathogenesis of allergic asthma. We have previously demonstrated in sensitized Sprague-Dawley (SD) rats that depletion of CD8(+) cells caused an increase in the late airway response (LAR) and cellular infiltration after antigen challenge. To better delineate the mechanism of CD8(+) cell involvement in the development of the LAR and airway inflammation, we investigated the pattern of chemokine and cytokine production after antigen challenge. SD rats were sensitized to ovalbumin (OA) and subsequently treated with anti-CD8 (OX-8) monoclonal antibody (mAb) for the depletion of CD8(+) cells or with control mouse anti-rat IgG(1) mAb as a control procedure. After OA challenge, CD8- depleted SD rats developed an increased LAR when compared with control rats (area under the curve: 16.65 +/- 6.6 in CD8- depleted rats versus 5.39 +/- 2.0 in control animals; p < 0.05). Compared with the control animals, the increase in the LAR was accompanied by a significantly increased eosinophilic infiltration of the airways and was associated with increased eotaxin expression (both messenger RNA [mRNA] and protein) in the CD8-depleted group. There were no differences between the groups in RANTES or monocyte chemoattractant protein-1 (MCP-1) expression. In addition, we found a significantly lower interferon gamma (IFN-gamma) mRNA expression in the CD8-depleted rats, without any effects on interleukin (IL)-4 and IL-5 mRNA expression when measured either by semiquantitative reverse transcriptase/polymerase chain reaction (RT-PCR) or by in situ hybridization for the number of cells expressing these cytokines. Taken together, these results suggest that CD8(+) cells from sensitized SD rats exhibit the functional capacity to suppress the LAR, possibly through downregulation of eotaxin expression and increased expression of IFN-gamma mRNA.