Does interleukin-1 save B cells from paralysis? Studies with pre-B cells and antigen-reactive B cells.

The role of the second messenger cAMP in the differentiation of the pre-B cell line 70Z/3 and in the initial phase of the immune response of B cells, IgM antibody production is examined. Our data indicate that in these B cells, the elevation of intracellular cAMP levels can have two fundamentally different effects: it may dedifferentiate B cells and cause their disintegration (catabolic pathway) or it may induce their differentiation and maturation (anabolic pathway). The switch that determines which pathway B cells enter is set by interleukin-1. Our experiments indicate that intracellular cAMP levels rise in B cells when they interact with helper T cells in a cognate interaction. Given the dual effect that cAMP may have on the fate of B cells, activation or destruction, our data may be taken to suggest that helper T cells may direct B cells into catabolic or anabolic responses, depending on the availability of a costimulatory signal mediated by interleukin-1.