Abstract
The mitogenic response of murine lymphocytes to the lymphocytosis-promoting factor of Bordetella pertussis has been shown to be due to activation of T cells. The selectivity of responsiveness to LPF with respect to the population of T cells which is stimllated, differs from that of PHA as well as Con A, and the surface receptors are different. A population of adherent cells, which does not appear to consist of macrophages or other phagocytic cells, is required for the T-cell response.