Electrophoretic assessment of aqueous and serum neurone-specific enolase in retinoblastoma and ocular malignant melanoma

Abstract

The isoenzyme pattern of enolase was examined in the aqueous humour and serum of patients with retinoblastoma (10 aqueous, 8 sera), malignant melanoma (4 aqueous, 25 sera), and normal subjects undergoing cataract surgery (25 aqueous, 30 sera). The assay we used allowed assessment of all three major isoenzymes, including the γγ isoenzyme (neurone-specific enolase). No enolase was detectable in normal aqueous; αα isoenzyme was present in the aqueous of one patient with malignant melanoma, while aqueous from all patients with retinoblastoma contained both αα and γγ. Normal serum contained only an αα band, while serum from patients with retinoblastoma contained αα, αγ, and γγ bands (7 sera, 87-5%), or αα only (1 patient, 12-5%). All sera from patients with malignant melanoma contained the αα band, with low levels of γγ in 16 (60%). In a single patient with Coats's disease aa was present in the serum, but no enolase was detected in aqueous. Increased amounts of γ-containing isoenzymes of enolase are found in both serum and aqueous from patients with retinoblastoma. In malignant melanoma there is often an increase in serum γγ enolase. The assessment of aqueous and serum enolase patterns may be of value in the diagnosis of retinoblastoma and malignant melanoma.