Specificity of tumor-associated antibodies in sera of patients with uveal melanoma.

We have identified antibodies against cytoplasmic components of allogeneic uveal melanoma cells in the sera of 16 of 31 patients with proven intraocular melanoma. Similar antibodies were found in 27% of controls and in 24% of patients with uveal nevi. The antibodies in these 3 groups of subjects were absorbed by components of uveal and cutaneous melanoma cells but not by those of normal choroidal melanocytes, normal uvea and retinal pigment epithelium, dermal nevus, pigmented skin or fetal cells. We found that specificity of the antibodies was also demonstrated by absence of reactivity with normal choroidal melanocytes, loss of reactivity after immune blocking, and absence of reactivity of melanoma antigen with conjugated antihuman immunoglobulin alone. Attempted absorption of the conjugated antihuman immunoglobulin by components of uveal melanoma cells did not alter the reactivity of the conjugated antihuman immunoglobulin.