THE IDENTIFICATION OF THE BETA-2-MICROGLOBULIN BINDING ANTIGEN ENCODED BY THE HUMAN CD1D GENE

Human cluster of differentiation (CD1) is a family of cell surface glycoproteins composed of a 43 - 49-kDa heavy chain non-covalently associated with beta-2-microglobulin. Five human CD1 genes have been detected and cloned. There genes (CD1A), -B and -C) encode the serologically defined CD1a, -b and -c antigens. Thus two genes remain, CD1D and CD1E, whose protein products have not been characterized so far. This report describes how a beta-galactosidase-CD1D fusion protein was used to raise specific antisera and a monoclonal antibody against the CD1D gene product. The monoclonal antibody defines a cell surface molecule expressed on a cortical thymocyte cell line and is composed of a 49-kDa heavy chain associated with beta-2-microglobulin, which is serologically distinct from CD1a.