Evidence for the linkage of the IGC H locus to a gene controlling the idiotypic specificity of anti-p-azophenylarsonate antibodies in strain A mice.

Anti-p-azophenylarsonate (anti-Ar) antibodies elicited in all strain A/J mice tested share one or more idiotypic specificities. These specificities are also found in the anti-Ar antibodies of mice of the closely related strain, AL/N, but not in those of BALB/c mice. Anti-Ar antibodies were elicited in congenic mice in which the IgC(H) locus of AL/N mice, which controls allotypic markers in the constant regions of heavy chains, had been introgressively backcrossed for nine generations onto a BALB/c background; the mice were then rendered homozygous for the AL/N allotypic determinant. On the average, these antibodies were quantitatively equivalent, with respect to content of the cross-reactive idiotype, to those of AL/N mice. This indicates that the gene controlling the idiotype is closely linked to the IgC(H) locus. Since idiotype must be a function of V region sequences, the results suggest close linkage of V(H) and C(H) genes. The cross-reactive idiotype was found in nearly all F(1) mice (C57/BL x A/J or BALB/c x A/J) tested.