Content of a cross-reactive idiotype in nonimmune A/J sera

The anti-p-azophenylarsonate antibodies of A/J mice express a major intrastrain cross-reactive idiotype (CRIA). Using a sensitive radioimmunoassay we were unable to detect significant quantities of molecules bearing CRIA in nonimmune A/J sera. The upper limit is 140 ng/ml. Possible reasons for variability of such data in the published literature are discussed.