Characterization of Rat CD1 Antigen with a Polyclonal Antibody Against a Recombinant Protein Produced by the Prokaryotic Expression System

CD1, the first cluster of differentiation antigens, is a family of cell surface glycoproteins which are noncovalently associated with β2-microglobulin. Although the structure of CD1 is similar to that of major histocompatibility complex class I molecules and cytolytic T cell lines specific for CD1 molecules have been established, which suggest that CD1 antigens may play a role as a presenting molecule, the actual function of CD1 is presently unknown. We have analyzed and identified the rat homologue of CD1 in attempt to confirm the function of CD1 and whether it has been conserved in evolution. The rat CD1 gene was categorized into the CD1D class. In this report, we produced a specific rabbit antiserum to rat CD1 by the prokaryotic expression system and investigated the expression of its antigen. According to FACS and immunohistochemical analyses with the polyclonal antibody, rat CD1 antigen was expressed on the surface of thymocytes and spleen cells, and was detected in hepatic tissue. The expression level of CD1D class in lymphoid organs varied among species. The functional significance of these results is discussed.departmental bulletin pape