• Using monoclonal antibody MAbA9-C6, which defines an epitope of retinal S antigen retained in fixed-tissue sections, we investigated S-antigen immunoreactivity in human fetal eyes from different gestational periods and 19 cases of retinoblastoma. S-antigen immunoreactivity was first observed in the outermost portion of the neuroblastic cell layer in the retina of a human fetus at 18 weeks' gestation, a stage preceding photoreceptor differentiation, and at all later stages examined thereafter. All adult eyes containing normal photoreceptors bound MAbA9-C6. In retinoblastomas, several different patterns of S-antigen immunoreactivity were recognized. In seven cases, S-antigen immunoreactivity appeared to be associated with normal photoreceptor elements incorporated into the growing tumor. S-antigen immunoreactivity was associated with fleurettes within the retinoblastoma in three cases and Flexner-Wintersteiner rosettes in seven cases. In 11 cases, S-antigen immunoreactivity was associated with isolated tumor cells. Our results show that S antigen may be a useful marker in the study of the embryologic development of the human retina and antigenic expression and modulation in retinoblastomas.
Donoso LA, Folberg R, Arbizo V. Retinal S Antigen and RetinoblastomaA Monoclonal Antibody Histopathologic Study. Arch Ophthalmol. 1985;103(6):855-857. doi:10.1001/archopht.1985.01050060115039