Genetic control of immune responsiveness to poly (LPro)--poly (LLys)-derived polypeptides by histocompatibility-linked immune response genes in the rat.

In rats responsiveness to branched synthetic polypeptides carrying a Pro--L backbone, such as (T,G)-Pro--L or (Phe,G)-Pro-L and to Pro--L itself is controlled by Ir genes which are linked to the major histocompatibility genes. The level of antibody production to these polypeptides does not fall into strict high or low responder categories but covers the range in between. (T,G)-pro--L and Pro--L elicit a very similar response pattern which, however, differs from that obtained with (Phe,G)-Pro--L. Anti-(T,G),Pro--L antibodies do not cross-react with (T,G)-A--L, but do so extensively with Pro--L. Anti-(Phe,G)-Pro--L antibodies show cross-reactivity to (Phe,G)-A--L only when the antibody-producing strain is a high responder to (Phe,G)-A--L. These results when considered in view of data obtained in mice on genetic control of the immune response to (T,G)-Pro--L suggest that at least two unlinked Ir genes are involved in controlling anti-Pro--L responsiveness.