Genetic mapping of an H-2-associated antigen expressed on regulatory T cells.

T lymphocytes that serve regulatory functions in the generation of effector T cells to alloantigen and to altered syngeneic cells express a distinguishing H-2-associated cell surface marker that we have termed Ha. Genetic mapping studies with the B10.A(2R), B10.A(4R), B10.A(5R), and LG/Ckc lines of mice have delineated the locus determining the expression of Ha to the right of H-2K and left of H-2IB or within the I-A region. Thus these regulatory T lymphocytes express Ia antigens.