Expression of cell surface sialic acid and galactose by normal adult human melanocytes in culture.

Normal adult human melanocytes grown either in the presence of phorbol ester or dialyzed hypothalamic extract were analyzed for their cell surface sialic acid and galactose content. In both cases, cells expressed large amounts of sialic acid, whereas they differed in their terminal nonreducing beta-D-galactosyl residues linked to N-acetyl galactosamine; such residues were accessible to peanut agglutinin and Bauhinia purpurea lectin on cells grown in phorbol ester and inaccessible on cells grown with dialyzed hypothalamic extract. In addition, striking differences in morphology and growth characteristics were observed between adult melanocytes grown with phorbol ester or with dialyzed hypothalamic extract. Thus, pure cultures of normal adult human melanocytes grown in the presence of dialyzed hypothalamic extract displayed cell surface properties different from those of melanocytes grown with phorbol ester. Cultures of melanocytes with dialyzed hypothalamic extract are likely to reflect known cell surface characteristics of human melanocytes in the skin. Such cultures could represent a useful model to study normal behavior and tumor progression of pigmented cells.