Ia Restriction Elements and Epitopes of Insulin Appear to be Recognized by Mouse T cells as Functional Units

Abstract

During the last years evidence has accummulated suggesting the identity of serologically detectable Ia antigens encoded in the I-A and I-E/C subregions of the mouse H-2 complex, Ia restriction elements for T cells, and the products of Ir genes. Thus, it would appear that the long debate about the cellular expression of Ir gene function has come to an end. However, it is still not clear how the expression of certain Ia molecules will lead to a specific low- or non-responsiveness. On the one hand, determinant selection models proposed a defect in antigen presentation such that the available Ia molecules cannot form a correct interaction product with the nominal antigen that can be recognized by T cells (1). On the other hand, very recent experiments led to the conclusion that non-responder macrophages are not defective in presentation of a non-permissive antigen. It was therefore proposed that non-responsiveness is rather due to a lack of T cells capable of recognizing the particular combination of nominal and Ia antigens (2,3).