Composite activities on B cells of products released by T cells activated by concanavalin A

Publisher Website
Google Scholar
Abstract
Supernatants from murine spleen cells cultured for 48 h in the presence of 1.0 μg of concanavalin A (Con A) induced polyclonal antibody synthesis in cultures of spleen cells from both normal and athymic mice in the absence of exogeneous antigen. Moreover, the Con A‐induced supernatant rescued B cells which had been rendered unresponsive by a tolerogen [haptenated poly(DGlu,DLys)]. The capacity of the supernatant to induce cell proliferation was studied under both high and low‐density culture conditions. In contrast to antibody secretion, proliferation was only detectable in low‐density cultures.The Con A‐induced supernatant also contained suppressive components, since the primary anti‐sheep red blood cell (SRBC) response was markedly suppressed when the antigen added to cultures consisted of SRBC which had previously been used for absorbing the supernatants. Absorbed supernatants displayed enhanced helper activity indicating that only the suppressor component was removable by antigen. The suppressive component was eluted from erythrocytes with ammonium thiocyanate and was itself strongly suppressive when added to cultures with fresh erythrocytes. Furthermore, the suppressive component proved to be highly antigen‐specific, as the SRBC‐absorbed factor did not affect the response to horse RBC.The results indicate that supernatants from Con A‐activated spleen cells contain both helper and suppressor factors, the latter having easily demonstrable antigen specificity. They further suggest that a nonantigen‐derived signal is sufficient to trigger both proliferation and antibody synthesis by B cells.