1Internal Medicine department, Sohag Faculty of Medicine, South Valley University and ²Microbiology and Immunology department, Faculty of Medicine, Assiut University.

The protective immunity to Mycobacterium tuberculosis is mediated by T-helper-1 (Th1) CD4+ cells which activate macrophages and up-regulate the immune response. During the course of the disease, the T-helper-2 (Th2) CD4+ cells might down regulate the immune system through secretion of specific cytokines. This study included 33 patients with active pulmonary tuberculosis, 21 patients with inactive disease and 20 healthy individuals as controls. T cell proliferation assay with PPD antigen showed higher stimulation index (SI) in the inactive compared to active tuberculous patients (9.53 ± 2.75 vs. 4.61 ± 1.67 respectively, P value < 0.001), reflecting the good status of the immune system towards mycobacterial antigen. The gamma interferon (IFN-g ) level (pg/ml) was significantly higher ( P values < 0.001) in the inactive than active tuberculous patients and controls (210.24 ± 58.57, 79.20 ± 21.79 and 32.89 ± 33.58 respectively). Similar results were shown for IL-2 where its level (pg/ml) in the inactive patients was significantly higher than active tuberculous patients (234.92 ± 51.47 vs. 99.26 ± 19.20 respectively). On other hand, IL-10 was significantly higher in the active than inactive patients (435.23 ± 78.22 vs. 235.98 ± 50.74 pg/ml respectively) indicating a dominant Th2 type response during the course of TB infection. Tumor necrosis factor alpha (TNF-a ) was significantly higher in active than inactive tuberculous patients (402.46 ± 57.44 vs. 188.64 ± 59.82 pg/ml respectively). The tuberculostatic effects of IFN-g and TNF-a in the active stage of the disease are discussed.