Induction and characterization of "autologous" anti-isiotypic antibodies.

Upon immunization with phosphorylcholine (PC), conventional BALB/c mice produce anti-PC antibodies bearing predominantly the idiotype characteristic of the BALB/c PC-binding myeloma protein TEPC 15 (T15). To investigate whether BALB/c mice are able to produce antibodies to the autologous T15 idiotype, conventional (T15-positive) and neonatally suppressed (T15-negative) BALB/c mice were immunized with purcific for the T15 idiotype. However, anti-T15 antibodies were more readily induced in neonatally suppressed mice which in turn produced higher anti-T15 titers than conventional mice. Such "autologous" anti-T15 antibodies are able to (a) change the idiotypic pattern of the anti-PC response of conventional BALB/c mice in situ and, (b) inhibit the induction of an anti-PC response in vitro by spleen cells from T15-positive but not T15-negative BALB/mice. Thus, BALB/c mice are capable of producing anti-T15 antibodies upon immunization with an isologous myeloma protein which bears the autologous T15 isiotype. We suggest that isiotypes should not be strictly considered as "self-antigens" since the dramatic increase in their concentration, subsequent to antigen stimulation, might confer upon them immunogenic properties not shared by self-antigens.