Expression of I-Ak class II genes in mouse L cells after DNA-mediated gene transfer.

The I-region of the mouse H-2 complex encodes I-region-associated or Ia antigens which are involved in lymphocyte interactions and in the regulation of immune responsiveness. Two Ia antigens, termed I-A and I-E, have been identified; both are cell-surface integral membrane glycoproteins which consist of two noncovalently linked polypeptide chains designated alpha (molecular weight (MW) approximately 34,000) and beta(approximately 28,000 MW). Their expression is restricted to B lymphocytes and to antigen-presenting cells such as macrophages. Inside the cell, these alpha beta dimers are associated noncovalently with a nonpolymorphic chain of 31,000 MW designated the invariant (Ii) chain. Cloning of 200 kilobases (kb) of the I-region from mice of the H-2d and H-2k haplotypes was accomplished recently in our laboratory, and the genes encoding the four polypeptide chains, A alpha, A beta, E alpha and E beta, were identified. We now describe the successful expression of I-Ak molecules in transfected mouse L cells.