Interleukin 17-Producing γδT Cells Increased in Patients with Active Pulmonary Tuberculosis

Although it has been known that y8 T cells may play an important role in the immune response to infection of Mycobacterium tuberculosis (M. tb), the mechanisms by which the T8 T cells participate in the innate and/or acquired immunity to tuberculosis (TB) have not been full elucidated. In the present study, 27 patients with active pulmonary TB and 16 healthy donors (HD) were performed. We found that proportion of IL-17-producing cells among lymphocyte was similar between TB patients and HD, whereas the proportions of γδ T cells in IL-17- producing cells (59.2%) and IL-17-producing cells in γδ T cells (19.4%) in peripheral blood were markedly increased in TB patients when compared to those in HD (43.9% and 7.7%, respectively). In addition, the proportions of IFN-γ-producing γδ T cells in TB patients were obviously lower than that in HD. Upon re-stimulated with M. tb heat-treated antigen (M. tb-HAg) in vitro, fewer IL-17-producing γδ T cells were generated from HD and TB patients, whereas IFN-γ-producing γδ T cells were increased in TB patients compared to that in HD. Our findings in TB patients and healthy human were consistent with other murine investigation that the IL-17- producing γδ T cells were main source of IL-17 in mouse model of BCG infection, suggesting that γδ T cells might be involved in the formation of tubercular granuloma in pulmonary TB patients, but need further identification. Cellular & Molecular Immunology. 2008;5(3):203-208.     

Association of KIR Genotypes and Haplotypes with Susceptibility to Chronic Hepatitis B Virus Infection in Chinese Han Population

Killer immunoglobulin-like receptor （KIR） genes can regulate the activation of NK and T cells upon interaction with HLA class I molecules. Hepatitis B virus （HBV） infection has been regarded as a multi-factorial disorder disease. Previous studies revealed that KIRs were involved in HCV and HIV infection or clearance. The aim of this study was to explore the possibility of the inheritance of KIR genotypes and haplotypes as a candidate for susceptibility to persistent HBV infection or HBV clearance. The sequence specific primer polymerase chain reaction （SSP-PCR） was employed to identify the KIR genes and pseudogenes in 150 chronic hepatitis B （CHB） patients, 251 spontaneously recovered （SR） controls, and 412 healthy controls. The frequencies of genotype G7 M, FZ1 increased in CHB patients compared with healthy control subjects. The frequency of genotype AH was higher in SR controls than that in both CHB patients and healthy controls. The carriage frequencies of genotype G and AH were higher; while, the frequencies of AF and AJ were lower in SR controls than those in healthy control subjects. The frequency of A haplotype was lower, whereas, the frequency of B haplotype was higher in CHB patients and SR controls than those in healthy controls. In healthy controls, haplotype 4 was found lower compared with that in CHB patients and SR controls and the frequency of haplotype 5 was higher in SR controls than that in other two groups. Based on these findings, it seems that the genotypes M and FZ1 are HBV susceptive genotypes; AH, on the other hand, may be protective genotypes that facilitate the clearance of HBV. It appears that the haplotype 4 is HBV susceptive haplotype, whereas, haplotype 5 may be the protective haplotype that facilitates the clearance of HBV. Cellular ＆ Molecular Immunology. 2008;5（6）：457-463.     

Immunotherapeutical Potential of Mycobacterium Vaccae on M. Tuberculosis Infection in Mice

Tuberculosis remains the worldwide infectious disease. To identify the therapeutic potential of M. vaccae in treating tuberculosis, M. vaccae was injected into Mycobacterium tuberculosis （M. tuberculosis） infected mice. The optimal dose of M. vaccae （22.5 μg/mouse） treated mice showed lower pathological change index, spleen weight index, lung weight index and vital M. tuberculosis count than those of the untreated group. Treatment with M. vaccae enhanced the percentages of CD3^＋ and CD4^＋ T cells, IFN-γ^＋CD4^＋ T cells, innate immune cells including NK cells, NK1.1^＋ T cells and γδ T cells, and reduced the percentage of IL-4^＋CD4^＋ T cells. Therefore, M. vaccae could protect the mice from M. tuberculosis infection and improved mouse innate and adaptive cell-mediated immunity, suggesting that M. vaccae is a potential immunotherapeutic agent in pulmonary tuberculosis. Cellular ＆ Molecular Immunology.     

结核分枝杆菌肝素结合血凝素在结核病免疫应答中的研究

Objective To investigate the immune protection of heparin-hinding hemagglutinin ad-hesin(HBHA) and to estimate its potential diagnostic value. Methods Native HBHA were used to stimu-late peripheral blood mononuelear cells (PBMCs) from different infected-cases including PPD negative healthy control, PPD positive latent tuberculosis(LTB) infection, pulmonary tuberculosis, and the IFN-γ/in the supernatant of culture was detected. Meanwhile, HBHA specific IgG antibody in the sera was detected by ELISA. Results The middle level of HBHA specific IFN-γ of the three groups were 49.5 pg/ml, 781.9 pg/ml and 341.8 pg/ml, respectively. IFN-γ of latent tuberculosis group was much higher than that of the control, and slightly higher than that of the patients with pulmonary tuberculosis. And the absorbency of the IgG antibody to HBHA in the three groups was 0.212±0.066, 0.224 ± 0.076 and 0.285±0.078. lgG an-tibody in the patients with pulmonary tuberculosis is higher than that of the healthy, including the control and the latent tuberculosis infection. Conclusion HBHA has good immunogenieity, and it can stimulate the LTB to release high level IFN-γ, suggests that the LTB doesn't develop active tuberculosis may rely on its protection. HBHA specific. IFN-γ release may identify 1,333 from the healthy. Anti-HBHA antibody plays an auxiliary role in the diagnosis of pulmonary tuberculosis.     

The interaction of influenza H5N1 viral hemagglutinin with sialic acid receptors leads to the activation of human γδT cells

Highly pathogenic avian influenza H5N 1 epidemics are a significant public health hazard. Genetically engineered H5N 1 viruses with mammalian transmission activity highlight the potential risk of a human influenza H5N 1 pandemic. Understanding the underlying principles of the innate immune system in response to influenza H5N 1 viruses will lead to improved prevention and control of these potentially deadly viruses, γδT cells act as the first line of defense against microbial infection and help initiate adaptive immune responses during the early stages of viral infection. In this study, we investigated the molecular mechanisms of γδ T cells in response to influenza H5N1 viral infection, We found that recombinant hemagglutinin （rHA） derived from three different strains of influenza H5N 1 viruses elicited the activation of γδ T cells cultured in peripheral blood mononuclear cells （PBMCs）. Both the cell surface expression of CD69, an early activation marker on γδ T cells, and the production of interferon-y （IFN-y） were significantly increased. Notably, the rHA protein-induced γδ T-cell activation was not mediated by TCRγδ, NKG2D or pattern recognition receptors （PRRs） or NKp46 receptors. The interaction of rHA proteins with sialic acid receptors may play a critical role in γδ T-cell activation. Our data may provide insight into the mechanisms underlyingγδT-cell activation in response to infection with H5N1 viruses.     

The Role of Innate Immune Cells in the Response of Heat-Treated Mycobacterium tuberculosis （M.tb） Antigens Stimulating PBMCs

The proliferation response of γδT cells to the antigen from heat-treated Mycobacterium tuberculosis H37Ra(M.tb Ag)was used as a good model in γδT cell research.From preliminary research it is found that activatedNK cells positively elevated γδT cells proliferation after simulating PBMCs with M.tb Ag.To investigatedifferent behaviors of NK cells,γδNKT cells,γδT cells and relationships between these cell subsets,activationand proliferation of different cell subsets of PBMCs in response to M.tb Ag were analyzed.We demonstratedthat NK cells,γδNKT cells and γδT cells could be activated after stimulation with M.tb Ag.γδNKT cells and γδTcells proliferated while the number of NK cells decreased after 11 day-simulation with M.tb Ag.Meanwhile,atthe early time of stimulation the cytotoxicity of PBMCs was enhanced.Cellular & Molecular Immunology.2004;1(6):467-470.     

Increased serum IL-10 in lupus patients promotes apoptosis of T cell subsets via the caspase 8 pathway initiated by Fas signaling

We sought to investigate the expression of Fas and FasL on T cell surface and caspase 8 involvement in T cell apoptosis promoted by serum IL-10 in systemic lupus erythematosus(SLE) patients.Cells and sera were obtained from 35 SLE patients.Apoptosis of T cells in patients with SLE was increased and associated with the SLE disease activity index(SLEDAI).Elevated expression of Fas and FasL on T cell surface contributed to increased apoptosis of T cells.Increased IL-10 in the sera of SLE patients was capable of inducing Fas and FasL expression on CD4~+T cell surface,promoting apoptosis of this cell subset.Decreased IL-10 serum levels and low expression of Fas were found in 5 patients of the first follow-up group after 2-month treatment.In another group with one-year treatment,the SLEDAI declined to inactive scores.Serum IL-10 was decreased significantly,and expression of Fas and FasL on T cells was also reduced.Declined apoptosis was predominant only in CD4~+T cell subset.When sera with high level of IL-10 were used to culture PBMCs from healthy controls,activated caspase 8 was elevated in CD3~+T,CD4~+T and CD8~+T cells.The study showed that serum IL-10 induced apoptosis of T cell subsets via the caspase8 pathway initiated by Fas signaling.Increased apoptosis of T cells contributes to autoantigen burden,which is pathogenic in the development of SLE.     

Schistosoma japonicum infection induces macrophage polarization

The role of macrophages （MФ） as the first line of host defense is well accepted. These cells play a central role in orchestrating crucial functions during schistosomal infection. Thus, understanding the functional diversity of these cells in the process of infection as well as the mechanisms underlying these events is crucial for developing disease control strategies. In this study, we adopted a Mqb polarization recognition system. M1 macrophage was characterized by expressing CD16/32, IL-12 and iNOS. M2 macrophage was characterized by expressing CD206, IL-10 and arg-1. In vivo （mouse peritoneal macrophages of different infection stages were obtained） and in vitro （different S. japonicum antigens were used to stimulate RAW264.7） were characterized by using the above mentioned system. NCA and ACA stimulated RAW264.7 express significantly higher levels of IL-12 while significantly higher levels of IL-10 were detected after soluble egg antigen （SEA） stimulation. The results showed that dramatic changes of antigen in the microenvironment before and after egg production led to macrophage polarization. Furthermore, through TLR blocking experiments, the TLR4 signaling pathway was found to play a role in the process of macrophage polarization toward M1. Our data suggest that macrophage polarization during S. japonicum infection had significant effects on host immune responses to S. japonicum.     

The expression of CD2 in chronic HBV infection

It was previously reported that several kinds of intercellular adhesion molecules are closely related to chronic HBV infection. The complex of CD2 and CD58 plays an important role in enhancing the adhesion of T lymphocytes to target cells, and promoting hyperplasia and activation of T lymphocytes. In this study, we detected the level of CD2 expressed on the surface of PBMC, the expression level of CD2 mRNA in PBMC and the percentage of CD2 positive cells in PBMC of patients with chronic HBV infection and compared them with the expression level of normal controls. We also determined the level of serum HBV DNA from patients with chronic HBV infection and from normal controls. The clinical characteristics of hepatic function were tested as well. The results showed that the expression of CD2 significantly increased with the severity of chronic HBV infection, which suggested that CD2 might contribute to the hepatocyte damage in chronic HBV infection. Cellular ＆ Molecular Immunology.     

IL-10-producing type 1 regulatory T cells and allergy

As an important subset of regulatory T （Treg） cells, IL-10-producing type 1 regulatory T cells （Trl）, have some different features to thymic-derived naturally occurring CD4^＋CD25^＋Foxp3^＋ Treg cells（nTreg cells）. Similar to nTreg cells, Trl also play important roles in the control of allergic inflammation in several ways. There is a fine balance between Trl and Th2 responses in healthy subjects. Skewing of allergic-specific effctor T cells to a Trl phenotype appears to be a critical event in successful allergen-specific immunotherapy and glucocorticoids and β2-agonists treatment. Trl suppress Th2 cells and effector cells of allergic inflammation, such as eosinophils, mast cells, basophils, through producing IL-10, and perhaps TGF-β. Understanding of Trl may be helpful in developing new strategies for treatment of allergic diseases.     

IL-17 and IFN-γ expression in lymphocytes from patients with active tuberculosis correlates with the severity of the disease

Th1 lymphocytes are crucial in the immune response against Mycobacterium tuberculosis. Nevertheless, IFN-γ alone is not sufficient in the complete eradication of the bacteria, suggesting that other cytokines might be required for pathogen removal. Th17 cells have been associated with M. tuberculosis infection, but the role of IL-17-producing cells in human TB remains to be understood. Therefore, we investigated the induction and regulation of IFN-γ and IL-17 during the active disease. TB patients were classified as High and Low Responder individuals according to their T cell responses against the antigen, and cytokine expression upon M. tuberculosis stimulation was investigated in peripheral blood and pleural fluid. Afterwards, the potential correlation among the proportions of cytokine-producing cells and clinical parameters was analyzed. In TB patients, M. tuberculosis induced IFN-γ and IL-17, but in comparison with BCG-vaccinated healthy donors, IFN-γ results were reduced significantly, and IL-17 was markedly augmented. Moreover, the main source of IL-17 was represented by CD4(+)IFN-γ(+)IL-17(+) lymphocytes, a Th1/Th17 subset regulated by IFN-γ. Interestingly, the ratio of antigen-expanded CD4(+)IFN-γ(+)IL-17(+) lymphocytes, in peripheral blood and pleural fluid from TB patients, was correlated directly with clinical parameters associated with disease severity. Indeed, the highest proportion of CD4(+)IFN-γ(+)IL-17(+) cells was detected in Low Responder TB patients, individuals displaying severe pulmonary lesions, and longest length of disease evolution. Taken together, the present findings suggest that analysis of the expansion of CD4(+)IFN-γ(+)IL-17(+) T lymphocytes in peripheral blood of TB patients might be used as an indicator of the clinical outcome in active TB.     

IL-12增强结核病患者中性粒细胞吞噬和杀伤结核杆菌的活性

目的:观察IL-12对结核病患者外周血中性粒细胞(PMN)对结核分枝杆菌(M.tb)吞噬和杀伤功能的影响.方法:结核病患者和正常人外周血与异硫氰酸荧光素( FTTC)标记的M.tb共同孵育不同时间后,用流式细胞术(FCM)检测PMN对M.tb的吞噬率;结核病患者和正常人外周血均加入2'7’二氯二氢荧光素二乙酸酯(DCFH-DA)作用,同时加或者不加M.tb共同孵育不同时间后,用FCM检测PMN的活化率并计算活性氧(ROS)产生量;不同浓度IL-12预先作用外周血后,再用上述方法检测PMN对M.tb吞噬率,活化率及产生ROS的变化.结果:结核病患者和正常人PMN对M.tb吞噬率,PMN活化率和ROS产生均随时间延长而增加,但结核病患者5 min吞噬率(51.82±6.93)％高于正常人(47.20±4.26)％(P＜0.05);IL-12预先作用后,结核病患者和正常人PMN吞噬率、PMN活化率和ROS的产生均随浓度增大而显著增加,两者之间无显著性差异.结论:结核病患者外周血PMN对M.tb的吞噬功能以及ROS产生与正常人无显著性差异,仅早期吞噬率较高.IL-12略增强PMN吞噬和产生ROS的反应能力.     

Phosphorylated STAT3 and PD‐1 regulate IL‐17 production and IL‐23 receptor expression in Mycobacterium tuberculosis infection

We studied the factors that regulate IL‐23 receptor expression and IL‐17 production in human tuberculosis infection. Mycobacterium tuberculosis (M. tb)‐stimulated CD4⁺ T cells from tuberculosis patients secreted less IL‐17 than did CD4⁺ T cells from healthy tuberculin reactors (PPD⁺). M. tb‐cultured monocytes from tuberculosis patients and PPD⁺ donors expressed equal amounts of IL‐23p19 mRNA and protein, suggesting that reduced IL‐23 production is not responsible for decreased IL‐17 production by tuberculosis patients. Freshly isolated and M. tb‐stimulated CD4⁺ T cells from tuberculosis patients had reduced IL‐23 receptor and phosphorylated STAT3 (pSTAT3) expression, compared with cells from PPD⁺ donors. STAT3 siRNA reduced IL‐23 receptor expression and IL‐17 production by CD4⁺ T cells from PPD⁺ donors. Tuberculosis patients had increased numbers of PD‐1⁺ T cells compared with healthy PPD⁺ individuals. Anti‐PD‐1 antibody enhanced pSTAT3 and IL‐23R expression and IL‐17 production by M. tb‐cultured CD4⁺ T cells of tuberculosis patients. Anti‐tuberculosis therapy decreased PD‐1 expression, increased IL‐17 and IFN‐γ production and pSTAT3 and IL‐23R expression. These findings demonstrate that increased PD‐1 expression and decreased pSTAT3 expression reduce IL‐23 receptor expression and IL‐17 production by CD4⁺ T cells of tuberculosis patients.     

Respiratory syncytial virus infection suppresses IFN-gamma production of gammadelta T cells

The immunological mechanisms by which respiratory syncytial virus (RSV) contributes to the development of asthma are poorly understood. gammadelta T cells are important in mucosal defence, and may contribute to the establishment of primary immune responses by producing cytokines early during respiratory infections. Thus, we used flow cytometry and intracellular cytokine staining to investigate the expression of interferon (IFN)-gamma and interleukin (IL)-4 by mitogen-stimulated gammadelta T cells from the peripheral blood of 15 hospitalized infants with RSV bronchiolitis, seven rotavirus-infected infants and eight normal controls. gammadelta T cells from RSV-infected infants had a lower proportion of IFN-gamma-producing cells (median, 4.00%; range, 0.58-6.60%) and a slightly but significantly higher proportion of IL-4-producing cells (median, 0.40%; range, 0.13-2.76%) than rotavirus-infected infants (median, 32.10%; range, 14.43-61.21%; P < 0.01, median, 0.00%; range, 0.00-0.00%; P < 0.05) in the acute phase. By contrast, differences in cytokine production by total CD3+ T cells did not differ significantly between patient groups. Thus, reduced IFN-gamma-production by gammadelta T cells in the peripheral blood of RSV-infected infants is accompanied by increased Th2 cytokine production during the acute phase of disease. At follow-up, eight children had recurrent episodes of wheezing. The frequencies of IFN-gamma-producing gammadelta T cells were significantly lower in patients who developed recurrent wheezing (median, 0.65%; range, 0.02-1.75%) than in patients without recurrent wheezing (median, 6.90%; range, 5.25-10.98%; P < 0.005). Cytokine production by gammadelta T cells may therefore be important in the pathogenesis of acute RSV disease, and play a part in the development of recurrent childhood wheezing after bronchilolitis.     

Regulation of human CD4(+) alphabeta T-cell-receptor-positive (TCR(+)) and gammadelta TCR(+) T-cell responses to Mycobacterium tuberculosis by interleukin-10 and transforming growth factor beta

Mycobacterium tuberculosis is the etiologic agent of human tuberculosis and is estimated to infect one-third of the world's population. Control of M. tuberculosis requires T cells and macrophages. T-cell function is modulated by the cytokine environment, which in mycobacterial infection is a balance of proinflammatory (interleukin-1 [IL-1], IL-6, IL-8, IL-12, and tumor necrosis factor alpha) and inhibitory (IL-10 and transforming growth factor beta [TGF-beta]) cytokines. IL-10 and TGF-beta are produced by M. tuberculosis-infected macrophages. The effect of IL-10 and TGF-beta on M. tuberculosis-reactive human CD4(+) and gammadelta T cells, the two major human T-cell subsets activated by M. tuberculosis, was investigated. Both IL-10 and TGF-beta inhibited proliferation and gamma interferon production by CD4(+) and gammadelta T cells. IL-10 was a more potent inhibitor than TGF-beta for both T-cell subsets. Combinations of IL-10 and TGF-beta did not result in additive or synergistic inhibition. IL-10 inhibited gammadelta and CD4(+) T cells directly and inhibited monocyte antigen-presenting cell (APC) function for CD4(+) T cells and, to a lesser extent, for gammadelta T cells. TGF-beta inhibited both CD4(+) and gammadelta T cells directly and had little effect on APC function for gammadelta and CD4(+) T cells. IL-10 down-regulated major histocompatibility complex (MHC) class I, MHC class II, CD40, B7-1, and B7-2 expression on M. tuberculosis-infected monocytes to a greater extent than TGF-beta. Neither cytokine affected the uptake of M. tuberculosis by monocytes. Thus, IL-10 and TGF-beta both inhibited CD4(+) and gammadelta T cells but differed in the mechanism used to inhibit T-cell responses to M. tuberculosis.     

Dysregulated production of interferon-gamma, interleukin-4 and interleukin-6 in early tuberculosis patients in response to antigen 85B of Mycobacterium tuberculosis

Both interferon-gamma (IFN-gamma) and interleukin (IL)-4 expression in T cells and IL-6 expression in cells of the monocyte/macrophage lineage were monitored using antigen 85B (Ag85B) protein and purified protein derivative (PPD) antigen in the early stages of tuberculosis (TB). We showed that the levels of cell-associated IFN-gamma and IL-4 (mRNA and intracellular cytokine) in Ag85B-stimulated T cells were significantly depressed in TB patients compared with those in healthy tuberculin reactors. On the other hand, the capacity of peripheral blood mononuclear cells (PBMC) to produce IL-6 spontaneously ex vivo was enhanced in patients (P < 0. 001), but their corresponding capacities to respond to Ag85B were not significantly different from those of normal donors. After 2 months of antituberculosis therapy, the mean blastogenic responses of Ag85B-stimulated PBMC from seven TB patients were increased 6. 1-fold (P = 0.011). Furthermore, the proportions of both IFN-gamma- (P < 0.01) and IL-4- (P = 0.05) producing T cells were significantly increased. However, those of IL-6-producing cells were diminished in response to Ag85B (P = 0.05). Our results suggest that there may be an altered regulation of IFN-gamma, IL-4 and IL-6 to Ag85B in the early stages of TB.     

TLR2 deficiency by compromising p19 (IL-23) expression limits Th 17 cell responses to Mycobacterium tuberculosis

CD4(+) T(h)1 cells producing IFN-γ are of extreme importance in controlling infections by Mycobacterium tuberculosis both in mice and in men. In addition to IFN-γ-producing T cells, IL-17-producing T cells (T(h)17) have been observed during mycobacterial infections. Nevertheless, their contribution for the host immune response to mycobacteria as well as the signals triggering M. tuberculosis -specific T(h)17 cell differentiation and maintenance are not fully understood. We show that signaling via Toll-like receptor (TLR) 2 has a major impact on the regulation of p19 (IL-23) expression in response to M. tuberculosis and therefore on the establishment of T(h)17 cell responses to M. tuberculosis infection. Diminished T(h)17 responses in the lung of M. tuberculosis -infected TLR2-deficient animals were not caused by defective cell differentiation in the draining lymph node (LN) but rather by reduced maintenance at the site of infection. Consistent with the decreased numbers of T(h)17 cells in the lungs of infected TLR2-deficient animals, we observed reduced expression of CXCL9, CXCL10 and CXCL11, chemokines involved in recall responses to M. tuberculosis. Our data provides insights into the TLR2 role in infection with M. tuberculosis, with implications in pathophysiology of the disease and vaccine design.     

CD4(+) T cell clones producing both interferon-gamma and interleukin-10 predominate in bronchoalveolar lavages of active pulmonary tuberculosis patients.

The pattern of cytokine production in T cell clones derived from bronchoalveolar lavages (BAL) of active pulmonary tuberculosis (TB) patients was analyzed in clones obtained by limiting dilution procedures which expand with high efficiency either total T lymphocytes, independently of their antigen-recognition specificity, or Mycobacterium tuberculosis-specific T cells. BAL-derived clones, representative of CD4(+) cells from five patients with active TB, produced significantly higher amounts of IFN-gamma than BAL-derived CD4(+) clones from three inactive TB donors or four controls (with unrelated, noninfectious pathology). Average IL-4 and IL-10 production did not differ significantly in the three groups. Although these data suggest a predominant Th1 response to M. tuberculosis infection in the lungs, the majority of BAL-derived CD4(+) clones produced both IFN-gamma and IL-10 and the percentage of clones with this pattern of cytokine production was significantly higher in clones derived from BAL of active TB patients than from controls. Only rare clones derived from peripheral blood (PB)-derived CD45RO(+) CD4(+) T cells of both patients (nine cases) and controls (four cases) produced both IFN-gamma and IL-10; instead, the IL-10-producing clones derived from PB T cells most often also produced IL-4, displaying a typical Th2 phenotype. Higher average amounts of IFN-gamma and IL-10 were produced by BAL-derived CD8(+) clones of four active TB patients than of four controls, although the frequency of CD8(+) clones producing both IFN-gamma and IL-10 was lower than that of CD4(+) clones. The M. tuberculosis-specific BAL-derived T cell clones from three active TB patients were almost exclusively CD4(+) and produced consistently high levels of IFN-gamma often in association with IL-10, but very rarely with IL-4. Unlike the BAL-derived clones, the M. tuberculosis-specific clones derived from PB CD45RO(+) CD4(+) T cells of three different active TB patients and two healthy donors showed large individual variability in cytokine production as well as in the proportion of CD4(+), CD8(+), or TCR gamma/delta(+) clones. These results indicate the predominance of CD4(+) T cells producing both the proinflammatory cytokine IFN-gamma and the anti-inflammatory cytokine IL-10 in BAL of patients with active TB.     

IL-23 and IL-17 in the establishment of protective pulmonary CD4+ T cell responses after vaccination and during Mycobacterium tuberculosis challenge

Interferon-gamma is key in limiting Mycobacterium tuberculosis infection. Here we show that vaccination triggered an accelerated interferon-gamma response by CD4(+) T cells in the lung during subsequent M. tuberculosis infection. Interleukin 23 (IL-23) was essential for the accelerated response, for early cessation of bacterial growth and for establishment of an IL-17-producing CD4(+) T cell population in the lung. The recall response of the IL-17-producing CD4(+) T cell population occurred concurrently with expression of the chemokines CXCL9, CXCL10 and CXCL11. Depletion of IL-17 during challenge reduced the chemokine expression and accumulation of CD4(+) T cells producing interferon-gamma in the lung. We propose that vaccination induces IL-17-producing CD4(+) T cells that populate the lung and, after challenge, trigger the production of chemokines that recruit CD4(+) T cells producing interferon-gamma, which ultimately restrict bacterial growth.