Cell-mediated immunity, especially from CD4+ T-lymphocyte function, plays an important role in eliminatig mycobacteria in tuberculosis. Reports on Th1-type and Th2-type cytokines in human tuberculosis are conflicting, and little is known about their role in tissue damage. We examined the cytokine responses of CD4+ and CD8+ T-lymphocytes in peripheral blood and bronchoalveolar lavage fluid (BAL) from 20 purified protein derivative skin-positive (PPD+) and from nine PPD skin-negative patients with active pulmonary tuberculosis. Parallel blood and BAL fluid samples from each subject were shortly incubated with or without PMA and ionomycin, and the proportions of CD4+ and CD8+ T-lymphocytes producing interferon- (IFN-) or interleukin-4 (IL-4) were measured by flow cytometry. There was no age or BMI difference of examiness between PPD+ and PPD- group. PPD- patients, in relation to PPD+ patients, had a significant higher percent of CD4+ T-lymphocytes in the BAL. No significant difference was found between groups in percent CD4+ T-lymphocytes in peripheral blood and CD8+ T-lyphocytes peripheral blood and BAL. At the same time, PPD- patients have shown a significant higher percent of CD4+ T-lymphocytes which produced IFN- in relation to the entire number activated CD4+ T-lymphocytes in a peripheral blood. No significant difference was found in the production IFN- of CD8+ T-lymphocytes peripheral blood and BAL and CD4+ T-lymphocytes in the BAL. CD4+ T-lymphocytes of peripheral blood in two PPD-patients produced IL-4 while the rest of the T-lymphocytes peripheral blood and BAL suppressed the production of this cytokine. Among PPD+ patients group we have found a higher percent of CD4+ as well as CD8+ T-lymphocytes which produce IFN- in BAL in relation to the peripheral blood, while the BAL in PPD- group was more active only in CD4+ production IFN-. These results suggest a higher immune activity in the blood of PPD- patients while the BAL is more active in both groups of examinees in relation to the peripheral blood. It suggests that the separation of T-lymphocytes, specially those producing IFN- from peripheral blood to the lungs, occurs in tuberculosis.