Immunofluorescent studies on chimpanzee humoral responses to human melanoma cells

Eight chimpanzees were immunized, each with a single melanoma cell line. It was found that the serum of only one of the eight chimpanzees showed immunofluorescence with four of the five melanoma cell lines at the membrane surface; but it showed no fluorescence with normal skin fibroblasts, WI-38 cells, HeLa cells, human or monkey kidney cells. With appropriate absorption studies it was found that the antiserum was specific to melanoma cell lines. Trypsinated cells showed bright patchy membrane fluorescence, whereas non-trypsinated cells showed bright full ring fluorescence. The chimpanzee's antibody was C'-fixing IgG. It was concluded that the immunized chimpanzee produced antibody to surface antigen(s) common to four of the five melanoma cell lines tested.