Cyclic Amp and Immune Responses

Abstract

Abstract In tests with sheep red blood cells as antigen, both poly A and poly A·poly U (= polyA:U) stimulated the appearance of antibody-forming mouse spleen cells under in vitro conditions, poly A:U being more potent than poly A. High concentrations of the single- or double-stranded polynucleotides were less effective than low concentrations, and very high concentrations of poly A:U inhibited the responses. Pretreatment of cells with poly A:U prior to cultivation produced as good or better responses than did the incorporation of polynucleotides into the medium, but such pretreatment was ineffective when poly A:U-treated cells were subsequently exposed to trypsin. Lymphocytes, rather than macrophages, seem to be the principal targets of stimulation. The modification of antibody formation in vitro can be attributed to an alteration of cyclic AMP-mediated events, particularly since cAMP itself as well as the supplementation of poly A:U with theophylline (a known stabilizer of cAMP levels) can increase the number of antibody-forming cells that can be activated in vitro in the presence of a given amount of antigen.