The objectives of this study are to demonstrate the specificity of sera from
melanoma patients undergoing autologous immunization and to localize
melanoma antigens on a cellular level. Five
melanoma patients were immunized with autologous
melanoma cells and Bacillus Calmette-Guerin. This immunization program was conducted at Tulane University. Indirect immunofluorescence using both viable and fixed
melanoma cells was employed. Four of five postimmune sera were reactive to five of seven
melanoma cell lines. Two of the four reactive
antisera showed positive binding with two additional
melanoma lines obtained from other laboratories. All these sera were negative against seven nonmelanoma lines. Negative controls consisted of sera from 65 nonimmunized
melanoma patients and 140 nonmelanoma patients. Membrane immunofluorescence (MIF) demonstrated sequential full MIF, capping, polarization, and extrusion of
antigen-antibody complexes on the cell surface. MIF inhibition showed shedding of
melanoma antigens in the culture medium.
Ethanol,
methanol,
formalin,
trichloroacetic acid, and
acetone yielded sharp MIF.
Isopentane and
isooctane gave bright cytoplasmic fluorescence. In conclusion, this study provides suggestive evidence for the existence of common
melanoma antigens as defined by the postimmune antimelanoma sera. These
antigens may be localized in the membrane or within the cytoplasm.