Definitive mapping of the immune response gene(s) for (T,G)-A--L to the I-A subregion.

Mice of strains B10, B10.A, B10.A(4R), B10.A(5R), and the new recombinant inbred strain B10.MBR (H-2 genotype Kb, Ik, Sk. Dq) were immunized with (T,G)-A--L and the primary (total and IgM component), and secondary antibody responses were measured by using radioimmunoassays. B10 and B10.A(5R) were high responders, whereas B10.A, B10.A(4R), and B10.MBR were low responders to (T,G)-A--L. Based on the genotypes of the strains utilized, the immune response gene(s) for (T,G)-A--L is located in the I-A subregion of the H-2 complex. The data are consistent with the concept that Ia antigens are Ir gene products.