Nonspecific recruitment of lymphocytes in purified protein derivative-induced lymphocyte proliferative response of patients with tuberculosis.

Peripheral blood lymphocytes (PBL) from tuberculosis patients were studied for their in vitro proliferative response stimulated with purified protein derivative (PPD)-tuberculin. Studies were designed to characterize the lymphocytes involved in the PPD-induced proliferation. PPD-responsive lymphocytes were eliminated in PBL by the procedure of cultivation of PBL with PPD in the presence of 5-bromodeoxyuridine and light illumination of the cultured cells. These PBL which lost PPD reactivity were no longer able to proliferate to PPD stimulation but were still capable of proliferation in the presence of both PPD and X-irradiated, autologous fresh PBL or upon addition of culture fluids from PPD-stimulated PBL. In addition, these nonspecifically activated lymphocytes released a soluble factor into the culture fluids which inhibited the migration of leukocytes. It was likely that large numbers of nonspecific T cells were induced to proliferate as a result of the presentation of specific T cells with the antigen PPD. It is suggested that a similar recruitment of lymphocytes by PPD-stimulated T cells takes place in vivo during the establishment of tuberculosis or antituberculous immunity or both.