Retinal S antigen and retinoblastoma. A monoclonal antibody histopathologic study
L. A. Donoso, R. Folberg and V. Arbizo
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.
