Identification of the sequence required for expression of the 2H4 epitope on the human leukocyte common antigens.

The anti-2H4 antibody, which subdivides the T4+ population of human T lymphocytes into T4+, 2H4+ suppressor-inducer cells and T4+, 2H4- helper cells, recognizes an epitope on a subset of the human leukocyte common antigens (LCAs). LCAs are a family of cell surface glycoproteins generated from a single gene by the differential usage of three exons near the NH2-terminus. Using cDNA clones corresponding to four of the different forms of LCA molecules, extracellular domains of the LCA molecules were synthesized in vitro. Immunoprecipitation of these molecules with the anti-2H4 antibody demonstrated that exon A is required for the expression of the 2H4 epitope.