Role of membrane receptors in the induction of an in vitro secondary anti‐hapten response I. Differentiation of B memory cells to plasma cells is independent of antigen‐immunoglobulin receptor interaction

Abstract

In these experiments, we show that the interaction of antigen and B cell surface immunoglobulin is not essential for the generation of an IgG in vitro response to the hapten p‐azophenyl‐lactoside (lac). In our experimental system, keyhole limpet hemocyanin (KLH) was first selectively attached either to H‐2, Ia or Ig receptors of lac‐primed B cells by a hapten sandwich technique or to Fc receptors by complexes of azophenyl arsonate (ars)‐coupled KLH and anti‐ars. The labeled cells were then cultured with KLH‐specific T cells for 5 days in the absence of antigen. Under all conditions of attachment we observed a significant anti‐lac IgG response. We have demonstrated an absolute requirement for KLH‐specific helper T cells. The results thus indicate that T helper cells are by themselves, regardless of the B cell antigen that serves to effect bridging, sufficient to activate B memory cells. We could find no evidence to support either a matrix theory or a two‐signal hypothesis as currently proposed.