CD27 contributes to the early systemic immune response to Mycobacterium tuberculosis infection but does not affect outcome

The development of a strong Th1-mediated adaptive immune response is considered of main importance for host defense against the intracellular pathogen Mycobacterium tuberculosis. The induction of a cellular immune response is not only dependent on the engagement of the TCR but also requires co-stimulation. In order to study the role of the co-stimulatory molecule of the tumor necrosis factor receptor family member CD27 during murine M. tuberculosis infection, we intranasally infected wild-type (WT) and CD27 knockout (KO) mice with 10(5) colony-forming units M. tuberculosis. Whereas there were no differences in bacterial growth, inflammation and IFNgamma production by CD4+ and CD8+ lymphocytes in the lungs early after infection, the number of splenic CD8+ T cells producing the key Th1 cytokine IFNgamma was lower in CD27 KO mice than in WT mice. After 6 weeks, CD27 KO mice had 3.6-fold higher mycobacterial counts in their lungs and displayed more pulmonary inflammation and increased numbers of infiltrated leukocytes. Despite these differences early in infection, an equal number of WT and CD27 KO mice died during a 43-week observation period and lung bacterial loads and inflammation were comparable in the surviving animals. Our data suggest that CD27 does not contribute to the local IFNgamma-mediated response and long-term protection against M. tuberculosis.     

肺结核患者外周血中Th细胞极化偏移及临床意义分析

目的:分析初诊肺结核患者外周血中CD4+T淋巴细胞及其亚型Th1和Th2细胞的改变,探讨其在肺结核病变过程中的临床意义。方法:取肝素抗凝全血,加RPMI1640培养液等体积混匀,依次加入1∶1 000稀释的PMA、1∶100稀释的Ion-omycin和1∶10稀释的Monensin,混匀后于37℃,5%CO2静置培养4小时或过夜。取100μl培养血细胞依次加入抗人CD3-Per-CP、CD8-APC、mIgG1-FITC、Rat IgG1-PE、IL-4-PE、IFN-γ-FITC抗体,按流式操作流程分别进行细胞膜和细胞浆内标记测定CD4+IL-4+(Th2)、CD4+IFN-γ+(Th1)两种细胞的水平。结果:初诊肺结核患者外周血中Th1水平均显著低于健康对照组(P0.01),而Th2水平则显著高于健康对照组(P0.05)。粟粒型肺结核患者外周血中Th1细胞含量显著低于浸润性肺结核患者(P0.05),而Th2水平显著高于浸润性肺结核和结核性胸膜炎(P0.05)。CD4+/CD3+T细胞比例在这三个病程中呈下降趋势,且粟粒型肺结核显著低于浸润性肺结核(P0.05)。糖尿病并肺结核患者Th1、CD4+/CD3+显著低于无糖尿病肺结核患者(P0.05),Th2含量则显著升高(P0.05)。15例重度肺结核患者经结核化疗与微卡治疗三个月后Th1、CD4+/CD3+水平较治疗前明显升高(P0.05),而Th2水平较治疗前显著降低(P0.01)。痰检或培养阳性与痰检阴性患者相比Th1、CD4+/CD3+水平呈下降趋势但无显著差异(P0.05),Th2细胞水平显著升高(P0.05)。结论:浸润性肺结核、结核性胸膜炎、粟粒型肺结核、糖尿病并肺结核患者存在着不同程度的免疫功能抑制,对Th1、Th2细胞水平与CD4+/CD3+比例测定有助于临床病情的判断和疗效观察。     

Bronchoalveolar neutrophils, interferon gamma-inducible protein 10 and interleukin-7 in AIDS-associated tuberculosis

During advanced AIDS tuberculosis (TB) often presents atypically with smear-negative and non-cavitary disease, yet immune features associated with this change are poorly characterized. We examined the local immune response in a cohort of Tanzanian AIDS-associated TB patients who underwent bronchoalveolar lavage. TB infection was confirmed in bronchoalveolar lavage (BAL) fluid by culture, probe and polymerase chain reaction (PCR). Among TB patients CD4 count correlated positively with the extent of cavitary disease as well as BAL TB load (qPCR C(T)). TB patients had significantly higher granulocyte-macrophage colony-stimulating factor (GM-CSF) than non-TB patients, and those with non-cavitary TB had significantly higher BAL interferon gamma-inducible protein (IP-10) and interleukin (IL)-7 than those with cavities. BAL neutrophils were as prevalent as monocytes/macrophages or epithelial cells, and immunohistochemistry revealed that neutrophils, monocytes/macrophages, and epithelial cells were major sources of the IP-10 and IL-7. These data suggest a dysregulated cytokine profile may contribute to the TB of advanced AIDS.     

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.     

Subpopulation structure of T-regulatory cells and proliferative response of blood lymphocytes in vitro under pulmonary tuberculosis

Subpopulation structure of T-regulatory cells and proliferative activity of blood lymphocytes in vitro in patients with different clinical forms of pulmonary tuberculosis were studied in this work. It has been shown that Trn--natural T-regulatory lymphocytes (CD4+CD25+Foxp3+) play a leading role in formation of immune suppression under infiltrative, disseminated and fibrosis-cavernous pulmonary tuberculosis. Besides, their number is increased in blood of both tuberculin-positive and tuberculin-negative patients. Negative correlation between the number of Trn and proliferative activity of blood lymphocytes (basal, mitogen- and antigen-induced)has been established, which testifies about participation of Trn in suppression of lymphocyte proliferation and Th1- and Th2-immune response.     

NKT细胞、NK细胞和T细胞亚群在活动性肺结核患者外周血的表达及意义

目的:探讨活动性肺结核病人外周血CD3+T、CD3+CD4+Th、CD3+CD8+Tc、CD3-CD16+56+NK、CD3+CD16+56+NKT、Th/Tc的表达变化及其临床意义。方法:采用流式细胞术分析45例肺结核病人、16例肺部感染病人及30例健康人外周血CD3+Th、CD3+CD4+Th、CD3+CD8+Tc、CD3-CD16+56+NK、CD3+CD16+56+NKT、Th/Tc的表达和变化情况。结果:初、复治肺结核患者的外周血NKT比例明显高于健康人(P<0.05);Th低于健康人(P<0.05);Tc高于健康人(P<0.05);Th/Tc低于健康人(P<0.05)。初、复治肺结核患者之间T、Th、Tc、NK、NKT、Th/Tc未见明显差异。肺部感染、活动进展Ⅰ期、活动进展Ⅱ期病人NKT阳性细胞数高于健康人和吸收好转期病人且结果有统计学意义(P<0.05);活动进展Ⅱ期组高于肺部感染组且结果有统计学意义(P<0.05)。活动进展Ⅰ期、活动进展Ⅱ期病人Tc阳性细胞数高于健康人组且结果有统计学意义(P<0.05)。Th/Tc吸收好转期、肺部感染、活动进展期、活动进展Ⅱ期均低于健康人组且结果有统计学意义(P<0.05)。轻症、中症、重症患者,重症者Th升高、Tc下降、Th/Tc升高。结论:NKT细胞与肺结核的发展和转归有关。Tc细胞的升高是免疫系统对于结核杆菌的反应,与肺结核病变的发展、范围和程度紧密相关。重点监测外周血NKT细胞和Tc细胞对于掌握活动性肺结核发展和预后有特殊的意义。     

Immunophenotypic characterisation of peripheral T lymphocytes in pulmonary tuberculosis

Background: The cellular immune response plays an important role in determining the outcome of infection and disease in Mycobacterium tuberculosis . Many studies of these disease interactions yield contradictory results. Aim: This study aims at determining the changes that take place in the subpopulations of T lymphocytes in the blood of patients with pulmonary tuberculosis (TB). Settings and Design: This cross-sectional study was done at King Khalid University Hospital, Riyadh, Saudi Arabia. Materials and Methods: Flow cytometry was used to determine the absolute numbers and percentages of T CD3, T CD4, T CD8, T CD19 and natural killer (NK) T cells in 54 patients with active pulmonary TB before the commencement of treatment and in 25 healthy PPD negative volunteers. Statistical Analysis: Statistical Package for Social Sciences (version 11.5) was used for analysis. Results: There were significant differences in the values of CD3, CD4 and NK T cells among the groups. The numbers of CD3 and CD4 cells were lower in subjects than in controls [1091.9 +/- 321.4 vs. 1364.6 +/- 251.2; P P P P = 0.761). Conclusion: There are significant changes in the cellular immune response particularly affecting the CD3, CD4 and NK T cells with the development of pulmonary TB. Therefore, further studies of these changes may have important implications on the development of diagnostic tools, vaccines and treatment modalities.     

The potential impact of CD4+ T cell activation and enhanced Th1/Th2 cytokine ratio on HIV-1 secretion in the lungs of individuals with advanced AIDS and active pulmonary infection

Bronchoalveolar lavage fluid (BALF) provides a source of mucosal CD4(+) T cells. We investigated the physiological properties of T lymphocytes from BALF and blood and their role on the dynamic of HIV-1 replication among AIDS patients with active lung infections. Pulmonary CD4(+) T cells consist mainly of effector memory cells (CD45RO(+) and CCR7(-)) with increased expression of activation markers (HLA-DR(+) and CD69(+)) when compared to the blood counterpart. We observed a high frequency of BALF cells capable of secreting HIV-1-Ags suggesting that the local lung environment may support favorable conditions for CD4(+) T lymphocytes harboring HIV-1 DNA to initiate the viral cycle. Nevertheless, the high number of IFN-γ-producing cells and the predominance of Th1 immune response in the lung could limit the secretion of HIV-1 RNA. In conclusion, the capacity of activated CD4(+) T cells to produce HIV-1 is driven by both the level and quality of cellular activation in the lung.     

Neonatal lung immune responses show a shift of cytokines and transcription factors toward Th2 and a deficit in conventional and plasmacytoid dendritic cells

The high incidence of lung‐damaging life‐threatening respiratory infections in infants may be related to the immaturity of their immune systems. To determine whether lung immune features differ in early life compared with those in adulthood, whole lung as well as lung T lymphocyte and DC responses were investigated in BALB/c neonates versus adults. Higher expression of GATA‐3 and rapid and sustained production of type 2 cytokines by lung explants after in vitro exposure to anti‐CD3 was the hallmark of the neonatal period, suggestive of a Th2 bias. Neonatal lung GATA‐3‐producing cells were identified as CD3⁺, CD4 and CD8 double‐negative T lymphocytes, a subset found at a higher frequency in neonatal than adult lung. The neonatal lungs contained fewer conventional DCs, with a lower ratio of CD103⁺ to CD11b⁺ DCs, and a much lower number of plasmacytoid DCs in comparison with adult lungs. Yet, when stimulated in vivo by BCG, neonatal lung DCs matured and primed adult naïve CD4⁺ T cells toward Th1 as efficiently as adult BCG‐primed lung DCs. Conversely, both adult and neonatal BCG‐primed lung DCs induced a Th2 cytokine response from neonatal naïve lymph node T cells, suggestive of an intrinsic feature of neonatal T lymphocytes.     

Improved outcome of chronic Pseudomonas aeruginosa lung infection is associated with induction of a Th1-dominated cytokine response

Repeated challenge with antigen is involved in the pathogenesis of a variety of pulmonary diseases. Patients with cystic fibrosis (CF) experience recurrent pulmonary colonization with Pseudomonas aeruginosa before establishment of chronic lung infection. To mimic recurrent lung infections in CF patients, the lungs of susceptible BALB/c mice were re-infected with P. aeruginosa 14 days after the initial infection. Singly-infected BALB/c mice, as well as non-infected mice, were used as controls. Decreased mortality and milder lung inflammation in re-infected BALB/c mice, as well as a tendency for improved clearance of bacteria, was observed when compared with singly-infected mice. The improved outcome in re-infected mice correlated with changes in CD4 cell numbers. Surface expression of LFA-1 on pulmonary CD4 cells was increased in re-infected compared with singly-infected mice. Moreover, resistance to re-infection was paralleled by a shift towards a Th1-dominated response and increased IL-12 production. No significant increase in serum IgG was observed in the re-infected mice. In conclusion, these results indicate a protective role for a Th1-dominated response, independent of antibody production, in chronic P. aeruginosa lung infection in CF.     

Changes in serum immunomolecules during antibiotic therapy for Mycobacterium avium complex lung disease

Little information is available regarding changes in immune status for patients with Mycobacterium avium complex (MAC) lung disease during antibiotic therapy. Serum immunomolecules from 42 patients with MAC lung disease were assayed comparatively using an array‐based system according to (i) patients with MAC lung disease at the time of diagnosis versus healthy controls and (ii) alterations after 12 months of antibiotic therapy in the MAC lung disease group. In addition, cytokine analyses were performed to determine whether cytokine responses were associated specifically with the disease phenotype, treatment outcome and aetiological agent. Notably, the serum concentrations of type 1 cytokine‐associated molecules, such as CD40L, interferon (IFN)‐γ, interleukin (IL)‐8 and IL‐23, were decreased significantly in patients at the time of diagnosis, suggesting that these molecules may serve as indicators of host susceptibility to MAC disease. Although the overall serum level of T helper type 1 (Th1)‐related molecules, such as CD40L and IFN‐γ, was restored after treatment, Th17‐related cytokines, such as IL‐17 and IL‐23, were down‐regulated significantly at 12 months post‐treatment compared to pretreatment. Furthermore, these cytokine patterns differed among patient subgroups. Decreased serum concentrations of IL‐17 and/or IL‐23 were associated with failure of sputum conversion, the fibrocavitary disease phenotype and M. intracellulare lung disease. Thus, the reciprocal balance between Th1 and Th17 immunity during antibiotic therapy for MAC lung disease is critical for dictating the treatment response. In conclusion, a low level of Th1‐related immunomolecules may perpetuate MAC lung disease, and the serum concentrations of Th17‐related cytokines can reflect the treatment outcome, disease phenotype and aetiological agent.     

Pulmonary immune responses to Propionibacterium acnes in C57BL/6 and BALB/c mice

Propionibacterium acnes (PA) is a gram-positive anaerobic bacterium implicated as a putative etiologic agent of sarcoidosis. To characterize the pulmonary immune response to PA, C57BL/6 and BALB/c mice were intraperitoneally sensitized and intratracheally challenged with heat-killed bacteria. C57BL/6 mice challenged with PA developed a cellular immune response characterized by elevations in Th1 cytokines/chemokines, increased numbers of lymphocytes and macrophages in lung lavage fluid, and peribronchovascular granulomatous inflammation composed of T- and B-lymphocytes and epithelioid histiocytes. T-lymphocytes in the lung lavage fluid showed a marked CD4+ cell predominance. In contrast, C57BL/6 mice challenged with Staphylococcus epidermidis (SE), another gram-positive commensal of human skin, and BALB/c mice challenged with PA, showed only a modest induction of Th1 cytokines, less pulmonary inflammation, and no granulomatous changes in the lung. Enhancement of Toll-like receptor expression was seen in PA-exposed C57BL/6 mice within 24 h after exposure, suggesting that induction of innate immunity by PA contributes to the robust, polarized Th1 immune response elicited by this bacterium. These findings suggest that PA-induced pulmonary inflammation may be a useful model for testing the contributions of both bacterial and host factors in the development, maintenance, and resolution of granulomatous inflammation in the lung.     

CD4+CD25+FoxP3+调节T细胞抑制肺结核患者特异细胞免疫

  目的 了解结核患者外周血中CD4+CD25+FoxP3+调节T细胞在抑制结核患者结核特异细胞免疫反应中的作用。 方法 使用细胞分离、流式细胞分析、细胞增殖和细胞因子测定等方法,比较结核患者及健康正常人群外周血中CD4+CD25+FoxP3+调节T细胞的量及功能特征的差异。 结果 结核患者外周血中CD4+CD25+FoxP3+调节T细胞数占CD4+细胞总数的比例显著高于健康正常人群;在BCG及ESAT-6的刺激下,结核患者外周血单个核细胞增殖能力和产生γ-干扰素的能力比健康正常人群明显增强。在BCG刺激下,结核患者外周血CD4-细胞产生γ-干扰素(1289.62±519.01)及白介素-10(1045.40±534.12)的能力比结核患者外周血BPMCs细胞产生γ-干扰素(624.50±261.13)及白介素-10(377.00±249.56)的能力显著增强(均p<0.05);在BCG及ESAT-6的刺激下,结核患者外周血CD4+CD25+调节T细胞显著抑制结核患者外周血CD4+CD25-细胞产生γ-干扰素及白介素-10。 结论 结核患者CD4+CD25+FoxP3+调节T细胞数量增多,抑制结核患者结核特异细胞免疫反应功能增强,可能与结核的发生、发展及转归有密切关系。     

Gamma interferon-producing CD4+ T lymphocytes in the lung correlate with resistance to infection with Mycobacterium tuberculosis

The human immune system efficiently limits the replication of Mycobacterium tuberculosis in most infected individuals. Only 5 to 10% of infected people develop clinical tuberculosis, a sign of the inability of the immune system to control the infection. We have studied the C3H/HeJ (C3H) and C57BL/6 (B6) inbred mouse strains, which differ in their susceptibility to tuberculosis, in order to ascertain the immunological determinants of a successful immune response against M. tuberculosis and to establish a system to identify genes that influence susceptibility to tuberculosis. We found that the resistant B6 mice were able to control infection in both the lung and spleen, while susceptible C3H mice were incapable of limiting bacteria growth, especially in the lung, and succumbed to infection within 4 weeks. We determined that the susceptibility of C3H mice was independent of the Toll-like receptor 4 (tlr4) genetic locus and allelic major histocompatibility complex differences. Although the splenic immune responses were similar in the two mouse strains, the local immune responses in the lungs of the infected mice differed greatly. The pulmonary immune response in resistant B6 mice was characterized by an early influx of both CD4+ and CD8+ lymphocytes that produced gamma interferon (IFN-gamma). In contrast, the immune response of C3H mice in the lung was characterized by a delayed and decreased influx of lymphocytes, which produced little IFN-gamma. These results suggest an important role for the early appearance of IFN-gamma-producing lymphocytes in the lung in resistance to infection with M. tuberculosis.     

Increased frequency of regulatory T cells and T lymphocyte activation in persons with previously treated extrapulmonary tuberculosis

Extrapulmonary tuberculosis may be due to underlying immune compromise. Immunosuppressive regulatory T cells (Treg cells), and CD4(+) T lymphocytes in general, are important in the host immune response to Mycobacterium tuberculosis. We evaluated T lymphocytes from patients after recovery from extrapulmonary tuberculosis, which may reflect conditions before M. tuberculosis infection. A case-control study was conducted among HIV-uninfected adults with previously treated extrapulmonary tuberculosis and 3 sets of controls: (i) subjects with previously treated pulmonary tuberculosis, (ii) close tuberculosis contacts with M. tuberculosis infection, and (iii) close tuberculosis contacts with no infection. Monocyte-depleted peripheral blood mononuclear cells (PBMC-M) were stained for CD4(+) CD25(hi) CD127(low) FoxP3(+) cell (Treg cell) and T lymphocyte activation. Both characteristics were compared as continuous variables between groups with the Kruskal-Wallis test. There were 7 extrapulmonary tuberculosis cases, 18 pulmonary tuberculosis controls, 17 controls with M. tuberculosis infection, and 18 controls without M. tuberculosis infection. The median Treg cell proportion was highest among persons with previous extrapulmonary tuberculosis (1.23%) compared to subjects with pulmonary tuberculosis (0.56%), latent M. tuberculosis infection (0.14%), or no M. tuberculosis infection (0.20%) (P = 0.001). The median proportion of CD4(+) T lymphocytes that expressed the activation markers HLA-DR and CD38 was highest for CD4(+) T lymphocytes from persons with previous extrapulmonary tuberculosis (0.79%) compared to subjects with pulmonary tuberculosis (0.44%), latent M. tuberculosis infection (0.14%), or no M. tuberculosis infection (0.32%) (P = 0.005). Compared with controls, persons with previously treated extrapulmonary tuberculosis had the highest Treg cell frequency, but also the highest levels of CD4(+) T lymphocyte activation. Immune dysregulation may be a feature of individuals at risk for extrapulmonary tuberculosis.     

Recombinant BCG coexpressing Ag85B,ESAT-6 and Rv3620c elicits specific Th1 immune responses in C57BL/6 mice

Tuberculosis (TB) remains to be an enormous global health problem. The inconsistent protection efficacy of Bacille Calmette-Guérin (BCG) calls for new vaccines for TB. One choice to improve the efficacy of BCG vaccine is recombinant BCG (rBCG). Experimental evidences have revealed that Ag85B, ESAT-6 and Rv3620c are important immunodominant antigens of Mycobacterium tuberculosis. In this study, we have constructed a novel rBCG expressing fusion protein Ag85B-ESAT6-Rv3620c and evaluated the immunogenicity of this rBCG in C57BL/6 mice. Results show that there is a strong TB-specific CD4⁺ and CD8⁺ T lymphocytes proliferation in mice immunized with this rBCG vaccine. A single dose immunization of rBCG could induce a significantly strong Th1 immune response characterized by an increasing ratio of antigen-specific IgG2b/IgG1 as well as a high expression level of Th1 cytokines such as IFN-γ, TNF-α and IL-2. This conclusion was confirmed by a decreased secretion of Th2 cytokine IL-10. Moreover, this rBCG induced a strong humoral response in mice with an increasing antigen-specific IgG titer. Therefore, we concluded that this rBCG could significantly increase both Th1 type cellular immune response and antigen-specific humoral response compared with BCG. The above observations demonstrated that rBCG::Ag85B-ESAT6-Rv3620c is a potential candidate vaccine against M. tuberculosis for further study.     

Recruitment of antigen-specific Th1-like responses to the human lung following bronchoscopic segmental challenge with purified protein derivative of Mycobacterium tuberculosis

Although the mechanisms of specific immunity to Mycobacterium tuberculosis in humans are poorly understood, responses of Th1-like CD4+ T cells appear to be essential for protection. We hypothesized that healthy individuals displaying positive skin-test responses to purified protein derivative of M. tuberculosis (PPD) would have the capacity to mobilize M. tuberculosis-specific Th1 cells to the lung in response to bronchoscopic challenge with PPD. Local instillation of 0.5 tuberculin units of PPD was followed 48 h subsequently by bronchoalveolar lavage (BAL) of PPD-challenged and control segments. In PPD-positive subjects, PPD challenge resulted in a 2.7-fold increase in total BAL cells and in an increase in the percentage of lymphocytes in BAL from 10 to 19%. The BAL lymphocytosis observed in PPD-challenged segments was characterized by an increased percentage of CD4+ T cells and by increased numbers of cells capable of antigen-specific interferon-gamma production. In contrast, PPD-negative subjects did not develop local inflammation following PPD challenge. These findings indicate that bronchoscopic challenge with PPD results in recruitment of antigen-specific recall responses to the lung. This novel approach may be useful in clarifying the basis of local immunity against M. tuberculosis, and could serve more generally as a model of the development of Th1-like responses in the human lung.     

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.     

Pulmonary tuberculosis and serum IgE

Several recent studies indicate that mycobacterium or viral infection may reduce IgE levels or suppress atopy or both. The present study was undertaken to investigate whether Mycobacterium tuberculosis infection and its successful treatment down-regulate serum total IgE levels, a marker of a Th2 response, due to enhancement of a Th1 response in adult patients with tuberculosis (TB). We prospectively studied the changes in serum total IgE and DTH response to tuberculin, a marker of a Th1 response in 10 healthy controls, 20 patients with pulmonary TB, and 19 asthma patients without TB. Measurement of serum total IgE and tuberculin skin tests were performed before initiation of treatment and after successful completion of 6 months treatment in TB patients, and at the corresponding intervals in controls and asthmatics. The initial serum total IgE concentrations were significantly higher in TB patients than in healthy controls (282 +/- 26 U/ml (mean +/- s.e.m.) in TB patients versus 126 +/- 56 U/ml in controls; P = 0.03). However, serum total IgE concentrations significantly decreased (282 +/- 26 U/ml before versus 151 +/- 12 U/ml after treatment; P = 0.03) and tuberculin indurations significantly increased (23.6 +/- 1.8 mm before versus 29.6 +/- 2.1 mm after treatment; P = 0.04) in TB patients. In contrast, initial serum IgE concentrations and tuberculin indurations did not differ significantly from post-observation data in both healthy controls and asthmatics (P>0.30). The present study confirmed that immune responses to M. tuberculosis down-regulate a Th2 immune response, and might contribute to the decreased prevalence of allergic disorders.