Immunochemical characterization of a human B lymphocyte differentiation antigen (p65)

A human B-cell differentiation antigen (BDA-1) with a molecular weight of 65,000 was identified by use of an anti-B-cell xenoantiserum. BDA-1 was isolated by immunoprecipitation of cell lysates from a B-lymphoblastoid cell line (SB) and from blood B lymphocytes (sIg+ER-) of four normal individuals. It was not detectable in cell membrane lysates from two T-lymphoblastoid cell lines (HSB-2 and MOLT-3) or from enriched normal T cells (sIg-ER+). BDA is single-chain molecule since its migration in SDS-PAGE gels was not altered by heating the protein to 100 degree C or by treatment with 2-mercaptoethanol. Immunodepletion experiments demonstrated that the antigen recognized by anti-BDA xenoantiserum has neither structural nor antigenic relationships with Ia-like antigen or beta 2-microglobulin.