Tuberculin purified protein derivative up-regulates the telomerase activity of peripheral blood mononuclear cells from patients with pulmonary tuberculosis

Telomerase activity was detectable in cells of tuberculous pleural effusion s at high percentage. To investigate the possible role of telomerase in the immune function, we examined the proliferating state and the expression of telomerase activity in peripheral blood mononuclear cells (PBMC) from 13 p atients with pulmonary tuberculosis (TB) and 13 healthy volunteers in respo nse to tuberculin purified protein derivative (PPD) challenge. Exposure of cells to phytohemagglutinin (PHA) significantly promoted PBMC proliferation during a 6 day-period in both TB patient and healthy volunteer groups. PPD treatment also significantly promoted PBMC proliferation during a 6 day-pe riod in TB patient group, but had no significant effect in healthy voluntee r group. During the same period, telomerase activity was detected in every PHA- and PPD-treated samples of the TB patient group. However, the telomera se activity was not detected in PPD-treated samples from healthy donors and all the untreated samples. Our results indicate that the telomerase activi ty in PBMC could be induced by PPD stimulation in TB patients. Telomerase a ctivity may thus play a permissive role in cell division and clonal expansi on of the immune cells in response to TB.