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-gamma were determined by flow cytometry, and IL-2, IL-4, IL-5, IL-10, IFN-gamma and TNF-alpha 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-gamma(+)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-alpha 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.