Studies on macrophage RNA involved in antibody production.

Abstract

A portion of the RNA (immunogenic RNA) from antigen-exposed macro-phages initiates antibody formation when added to spleen (or lymph) cells in tissue culture. The antigen (or an antigen fragment) is associated with the immunogenic RNA. The immunogenic RNA from bacteriophage-infected macrophage cells is in a rapidly sedimenting form, but its activity is unimpaired in a state corresponding to 4-6S. This RNA hybridizes with macrophage DNA and yields a characteristic 3-peaked pattern upon elution at very low ionic strength. This RNA is slowly labeled and by hybridization is indistinguishable from RNA present in uninfected macrophages. Its composition corresponds to 54% guanine plus cytosine, differing greatly from the macrophage DNA. This RNA component which is associated with protein in both infected and uninfected macrophage cells separates from the bulk of the macro-phage RNA in a Cs2 SO4 gradient. Incubation with pronase eliminates both the immunogenic activity and the minor band in CS2SO4 where this activity concentrates. This immunogenic RNA-protein complex may be the essential means by which the information eliciting specific antibody production is processed, even though the RNA itself is not specific.