Abstract
Three types of idiotypic specificities compose the major idiotype of anti‐poly (L‐Glu^60^‐L‐Ala^30^‐L‐Tyr^10^) (GAT) antibodies from BALB/c mice (idiotype termed GAT‐715). Assays have been designed to analyze and study the distribution of these specificities. The highly conserved idiotypic specificity (h.c.GAT) has been assayed by the binding of serum 715‐7A4 to radiolabeled rat anti‐GAT antibodies. Guinea pig and mouse anti‐GAT antisera all express the same h.c.GAT specificity. The public specificity (p.GAT) has been shown to be present in an identical form in all anti‐GAT antisera from all strains of mice studied. The assay used for p.GAT was the binding of serum 715‐7A4 to C57BL/6 anti‐GAT antibodies that express only p.GAT. Finally, the strain‐restricted specificity s.r.GAT has also been investigated by radioimmunoassay; this specificity is expressed only by strains BALB/c, BALB/b, BUB/J, DBA/2, DBA/1 and ATL. This expression is independent of known allotypic markers. However, the expression of the s.r.GAT specificity of BALB/c mice follows the genetic distribution of V~H~ genes of BALB/c origin indicating that s.r.GAT can be considered as a genetic marker of some V~H~ gene(s) involved in the specific immune response to the GAT terpolymer.