Surface immunoglobulins of lymphocytes in mouse plasmacytoma. IV. Evidence for the persistence of the effect of plasmacytoma-RNA on the surface immunoglobulins of normal lymphocytes in vivo and in vitro.

The previous findings were confirmed that RNA extracted from murine plasmacytoma alters the character of the lymphocyte surface immunoglobulins (SIg) to express the idiotypic specificity of the Ig of the plasmacytoma from which the RNA was derived (cell conversion). RNA extracted from spleens of plasmacytoma-RNA-injected BALB/c mice also had convering activity, and if injected into other mice, caused the appearance of RNA active in cell conversion in spleens of the second set of mice. This activity was lost only after two additional transfers. When splenic cells from animals 1 hr after injection with RNA extracted from MOPC 300, LPC-1 or MOPC 104E, were cultured for 7 days, the proportion of cells with the SIg specific for these tumours increased. The cell-converting activity of the RNA extracted from the cultured cells after 7 days incubation ('7-day' RNA) was higher than that of RNA extracted from cells after 1 hr incubation ('immediate' RNA). 'Seven-day' RNA could be used for sequential transfers without marked loss of activity in cell conversion for at least five transfers. The repetitive transferability of this phenomenon by the injection of plasmacytoma-RNA suggests the possibility of RNA replication in the recipient cells.