[Lectin histochemistry of choroidal malignant melanoma]

Tumor specimens of malignant choroidal melanoma from a 50 year-old man were studied with reference to labeling with fluorescence-labeled lectins: wheat germ agglutinin (WGA), specific for sialic acid and N-acetylglucosamine, and Ricinus communis agglutinin-1 (RCA-1), specific for galactose. Epithelioid cells occupying the apex and internal portion of a dome-shaped tumor had intense labeling of WGA but little binding to RCA-1. Spindle-shaped cells in the base of the tumor were labeled moderately with WGA and faintly with RCA-1. Neuraminidase treatment of the specimens led to a marked increase in the RCA-1 binding to both epithelioid and spindle-shaped tumor cells. The results suggest association of the malignancy of choroidal melanoma cells with oligosaccharides of cell membrane-bound glycoconjugates.