Effect of different fixatives on the localization of human melanoma antigens by immunofluorescence

This study was designed to study the effect of different fixatives on melanoma antigens by immunofluorescence. Two postautoimmune antimelanoma sera were tested on two human malignant melanoma cell lines fixed with different fixatives by indirect immunofluorescence. Ethanol, methanol, formalin, trichloroacetic acid and acetone gave sharp membrane fluorescence. Minimal to moderate cytoplasmic fluorescence was seen with acetone but none with the others. Formalin gave the highest membrane fluorescent antibody titers at 1/512. Isopentane and isooctane yielded bright cytoplasmic fluorescence. Weak diffuse cytoplasmic fluorescence was seen with glutaraldehyde. Fluorescence was completely abrogated by paraformaldehyde. No fluorescence was seen with four nonimmunized melanoma sera and phosphate-buffered saline when used as controls. It can be concluded that different fluorescent patterns were seen on melanoma cells when different fixatives were used.