Properties of peritoneal exudate lymphocytes that mediate tuberculin delayed-type hypersensitivity and anti-tuberculosis immunity.

Rats were immunized with living BCG and acute peritoneal exudates were induced on the ninth day of infection. The peritoneal exudate cells (PEC), that confer adoptive anti-tuberculosis immunity and tuberculin delayed-type hypersensitivity (DTH), were subject to velocity sedimentation analysis. It was found that the ability to confer immunity of DTH was limited to a population of cells that sedimented at a rate of 3-4 mm/h. This sedimentation rate corresponds to that of small lymphocytes. No significant immunological activity was detected in large lymphocytes that incorporate [3H]-thymidine in vitro, regardless of whether the exudates were obtained 14 to 24 h after induction of peritoneal inflammation. The failure of large lymphocytes to confer immunity and DTH was not due to adherent cells with suppressor activity, because removal of adherent cells failed to amplify the transfer of immunological activity by non-adherent cells. The persistence of the ability to express immunity and DTH in adoptively immunized rats was studied. There was no decay of adoptive immunity during a 4 week period following cell transfer, but there was a rapid reduction in the expression of DTH.