Immunogenicity of CD63 in a patient with melanoma

CD63 is a member of the tetraspan family of molecules that is expressed in melanoma and which appears to be involved in regulation of motility and adhesion of melanoma cells. In the present study we have screened a cDNA library from a melanoma cell with antisera from a patient with melanoma and have shown that one of the antigens identified was CD63. The clone isolated contained a mutation in the transmembrane region, but this did not appear to be involved in immunogenicity of the molecule. Antisera from the patient showed weak reactivity with CD63 from melanoma and recombinant CD63 in Western blots. The latter studies showed marked variation in the fractions of CD63 identified with monoclonal antibodies to CD63 consistent with variable glycosylation of CD63. We suggest that glycosylation may account for its recognition by the human immune system. Further studies are required to assess the role of CD63 as an immunogen in melanoma.