Peptide antigen presentation by non-classical MHC class I molecules.

The mouse major histocompatibility complex contains more than 40 class I genes in addition to those encoding the classical class I molecules. Many of these encode functional class I heavy chains that are expressed and displayed on the cell surface in association with beta 2-microglobulin. Several laboratories, using genetic, biochemical, and molecular analysis, RMA-S mutant cells, and synthetic peptides, have recently shown that mouse non-classical or class Ib molecules present peptide antigens to T lymphocytes with alpha beta or gamma delta receptors. The class Ib genes, with their limited polymorphism, may have evolved to serve specialized presentation functions.