Toxic-shock-syndrome toxin 1-induced proliferation of lymphocytes: comparison of the mitogenic response of human, murine, and rabbit lymphocytes

Toxic-shock-syndrome toxin 1 (TSST 1) produced by Staphylococcus aureus induced in vitro proliferation of lymphocytes isolated from rabbit spleens, murine spleens, and both human peripheral blood and cord blood. This mitogenic response was nonspecific in all three systems. In the mouse and human systems, proliferation depended upon the presence of macrophages in the responding lymphocyte population. Inability to remove macrophages from rabbit splenocyte suspensions made it impossible to determine the contribution of this cell in rabbit splenocyte proliferation. Kinetic analysis of TSST 1-induced mitogenicity showed that proliferation of lymphocytes was maximal between days 4 and 6 in each of the three systems examined. Sensitivity to TSST 1 was similar in each system, with maximal proliferation achieved at TSST 1 doses as low as 0.1 ng/5 X 10(5) murine splenocytes or 2 X 10(5) rabbit splenocytes, and 0.01 ng/3 X 10(5) human mononuclear cells from human peripheral blood. Study of separated populations of mouse splenocytes and mononuclear cells from human peripheral blood showed that the TSST 1-induced proliferative response resided solely in the T cell populations.