Enhancement by TP-1, a thymic extract, of pokeweed mitogen-induced differentiation of B cells from normal subjects but not of those from patients with systemic lupus erythematosus

We studied the ability of TP-1, a calf thymic extract, to influence in vitro pokeweed mitogen (PWM)-induced plasma cell generation and blastogenesis of peripheral blood lymphocytes from normal donors and from patients with systemic lupus erythematosus (SLE). In normal subjects, TP-1 significantly increased plasma cell generation, but did not affect the mitogenic response to PWM. On the contrary, differentiation of B cells from SLE patients was not enhanced by this extract. The action on the differentiation of normal B cells could either be due to a direct effect on B cells or be mediated by activation of helper T cells.