The relation of idiotype expression to isotype and allotype in the anti‐p‐azobenzenearsonate response

AbstractThe distribution of idiotype‐positive plaques in mice of various strains injected with T‐independent (TI) and T‐dependent conjugates of p‐azobenzenearsonate (Ars) has been investigated. With maturation of the responses there is a progressive loss of dominance of the major cross‐reactive idiotype (CRI) in A/J and C.AL‐20 mice. The extremes are represented by the predominantly CRI+ IgM plaque response to a single injection of the TI antigen, Ars‐coupled Brucella organisms (Ars‐Br), and the low frequency of CRI+ plaques in the polyisotypic response elicited by Ars‐KLH (keyhole limpet hemocyanin) in adjuvant. The secondary response to Ars‐Br was characterized by an intermediate display of idiotype‐positive plaques in IgM, the IgG subclasses and IgA. Detailed analyses of the distribution of CRI+ plaques between isotypes in 60 mice hyperimmunized with Ars‐KLH revealed that the expression of idiotype in any of the IgG subclasses and IgA was constant and independent. This is interpreted to indicate random assembly of VH with Cγ and Cα genes during the switch.BALB/c and C3H mice also express a predominant idiotype during primary and secondary responses to Ars‐Br as detected by our heterologous anti‐A/J CRI serum. These strains only very rarely maintain the idiotype after hyperimmunization with Ars‐KLH. We conclude that hyperimmune responses which probably involve multiple modes of regulation give a poor indication of the germ‐line V gene repertoire.