Induction of antibody synthesis by purified immunogenic RNA in vitro.

Abstract

WE have described an RNA fraction derived from phenol-extracted livers of immunized rabbits, which induced specific antibody production when mixed with normal rabbit spleen cells in vitro1,2. Similar fractions have been described by others using spleen, lymph node or peritoneal exudate cells of mice, rats or rabbits3–12 as sources of the RNA fraction. In all cases it has been assumed that the RNA-donor cell type was a macrophage. Considerable controversy has been generated by these experiments and data have been published to show that (a) the RNA is neither specific13 nor newly synthesized14 and (b) the RNA fraction contains antigen or fragments thereof15–18. Here we show that the data obtained with the rabbit-DNP system2 extend to another laboratory model, the mouse-sheep red blood cell (RBC) system. Our earlier work1,2 suggested that the immunogenic RNA is produced in the macrophage cell, that it is specific and that it is confined to a discrete fraction of the extractable RNA. For these reasons we thought it desirable (a) to compare directly the capacities of both liver and spleen tissue RNA extracts to induce antibody-plaque-forming cells in vitro, (b) to compare the effects of RNAase and pronase on the immunogenic capacity of the RNA fraction and (c) to investigate the distribution of the immunogenic RNA fraction relative to the total RNA fractions.