Suppressor and helper T-cell populations in Mycobacterium kansasii-infected spleens.

Specific pathogen-free B6D2 F1 hybrid mice were infected intravenously with increasing numbers of Mycobacterium kansasii TMC 1203 or 1214 and blastogenic responsiveness of the splenic T cells to phytohaemagglutinin (PHA), Con A or to a mixed lymphocyte reaction (MLR) were compared. Mice which had been infected 30 days earlier with M. kansasii strain 1203 exhibited substantial suppression whereas those infected with 1214 showed enhanced tritiated thymidine uptakes when exposed to mitogenic or allogeneic stimulation. Spleen cells harvested from mice infected 10 days earlier with either M. kansasii 1203 or 1214 exhibited substantially enhanced levels of helper T-cell activity in vitro compared with normal spleen cells. As the M. kansasii 1203 infections progressed, increasing suppressor T-cell activity was observed so that by day 30, the helper T-cell response had been largely ablated. On the other hand, the M. kansasii 1214-infected spleens exhibited little or no suppressor T-cell activity at any time during the infection. However, helper T-cell activity doubled over this same time period relative to that for the 1203-infected spleens when the responses were compared on a cell-to-cell basis.