Monoclonal IgM surface immunoglobulin on lymphocytes of aging NZB mice and its induction in young mice by RNA.

The increase in serum immunoglobulins in aged NZB mice is associated with the appearance of a monoclonal IgM. The decrease in the proportion of circulating lymphocytes with normal receptors (IgM and IgG) of the aging NZB mouse is due to the replacement of these surface immunoglobulins by a monoclonal IgM. RNA extracted from spleen and plasma of aging NZB mice induced the development of such monoclonal receptors on normal lymphocytes and . RNA was detected in plasma of aging NZB mice bound to an α-globulin. Evidence is presented suggesting that the mediating factor in the development of monoclonal receptors is plasma RNA. Receptor conversion, previously also detected in plasmacytoma of mice appears to be a cause of B-cell dysfunction interfering with the normal sequence of the immune response.