[Retinal S-antigen and retinoblastoma--an immunohistochemical study]

A strain of monoclonal antibody, MabAgC6, which defines an epitope in S-antigen, was used to study S-antigen expression in 10 cases of retinoblastoma, where S-antigen immunoactivity was observed in different patterns: the "normal" photoreceptor elements incorporated in 3 cases of growing tumors, 3 of 4 fleurettes and E-W rosettes, and scattered tumor cells in 50% of the cases were stained positive. The results suggest that the expression of S-antigen in retinoblastoma may be used to assess the degree of tumor differentiation, as another of the tumor markers.