Human B cell function in responder and non-responder individuals. II. The role of T helper cells in promoting the PWM-induced B cell production of immunoprotein.

Sorted OKT4+ cells treated with pokeweed mitogen (PWM) and subsequently X-irradiated were used as a source of helper T cells to examine human T and B cell function. PWM-induced immunoprotein synthesis by human peripheral blood lymphocytes was the model used to study the cellular interactions. PWM was shown to induce helper T cell function which caused non-PWM treated B cells to secrete immunoglobulin. PBL from certain individuals could not be induced by PWM to secrete Ig therefore allogeneic co-cultures of helper T cells and B cells were examined to define the defective cell population. Ig synthesis in allogeneic cultures of T and B cells was always greater than that observed in autologous cultures when cells from responders were assayed. However, when allogeneic cultures were initiated using B cells from a responder and PWM treated T cells from a non-responder and examined for Ig synthesis, the B cell responses were markedly lower than seen in the autologous responder cultures. In addition, PWM activated helper T cells from a responder induced a significantly higher Ig synthesis by B cells from a non-responder. These observations indicate that PBL from individuals who do not respond in a PWM driven Ig synthesis assay have relatively normal B cell function but are deficient in helper T cell function.