Formation of Antibody in Rabbit Spleen Cell Cultures Stimulated with Immunogenic RNA

Cultures of dispersed rabbit spleen cells respond with specific antibody formation when exposed to ribonucleic acid (RNA) preparations from rabbit macrophages that have been incubated with one of two antigenically distinct phages. When large doses (350 µg) of RNA are employed, antibody formation is demonstrable within 24 hr; with smaller doses (100 µg) there is an apparent lag of 2 to 3 days. Both IgM and IgG antibodies are produced and antibody formation is sustained for 1 week. Ribonuclease but not Pronase destroys the immunogenicity of the RNA responsible for the early response. Of the three major fractions obtained by passing the RNA through a column of methylated bovine serum albumin-Kieselguhr, those representing 16 and 28S RNA are immunogenic while the RNA of 4 to 5S size is inactive. Both adherent and nonadherent spleen cells appear to be required in the response to RNA, but cell proliferation appears to be not essential to antibody formation when it is initiated by RNA.