Analysis of antigenic determinants of retinal S-antigen with monoclonal antibodies.

Eight murine monoclonal antibodies to retinal S-antigen were found to recognize three antigenic clusters in competitive binding experiments. Variable patterns of immunohistochemical staining of retinal sections supported the competitive binding studies. Monoclonal antibodies to two of these three antigenic clusters on S-antigen reacted by Western immunoblotting with both intact S-antigen and two cyanogen bromide cleaved peptide fragments of bovine S-antigen. The binding of the monoclonal antibodies was localized to epitopes contained on two peptide fragments of 26,000 and 18,000 molecular weight. The same peptide fragments also react with polyclonal rat or rabbit antisera to bovine S-antigen. Monoclonal antibodies to the third antigenic cluster did not react with either intact or fragmented S-antigen in immunoblotting studies.