Genetic control of the humoral response to an H-2 public specificity

The humoral response of mice to an H-2 public specificity, termed H-2. '28' was found to be under genetic control. The genes determining this specificity were mapped to both the H-2K and H-2D regions, suggesting possible structural homologies between the products determined by these two regions. Genetic analyses indicated that a single non-H-2-linked gene regulates the anti-H-2. '28' response. In a backcross study, no linkage was detected between this putative H-2. '28' Ir gene and either the V H region or the Ly-2 locus to which the K-light chain locus is linked. Thus, a regulatory rather than a structural genetic locus seems a more likely basis for differences in response to this antigen. Our data further indicate that control of the humoral response to H-2. '28' is determinant specific since responses of the same backcross mice to other K and D alloantigens were not found to be subject to the same control.