Stimulation of Malignant Skin Cells by Antibody to Normal Skin Cells of Mice 2 3

Abstract

The ability of antibodies developed against normal skin cells to stimulate skin cells transformed by 7,12-dimethylbenz[a]anthracene (DMBA) was investigated. Primary cultures of normal skin, containing both fibroblasts and epithelial cells, were established from epidermis of the back skin of adult strain A/J mice. Malignant skin cells were obtained by treating a subculture of normal cells with DMBA. Transformation was demonstrated by increased growth rate, growth in soft agar, and production of tumors in strain A/J mice. Antisera developed in New Zealand White rabbits against the normal cells were cytotoxic to both normal and malignant cells in the presence of complement of 1:320 dilution. However, greater dilutions of the antisera (1:500-1:1,000) in the absence of complement produced growth enhancement of the malignant but not of the normal cells. The growth-enhancing properties were present in the gamma-globulin fraction of the antisera that contained IgG, IgM, and IgA antibodies. Immunofluorescence studies indicated that antibodies from the sera bound to the membranes of both normal and malignant cells. These data indicate that antibodies to normal cells are stimulatory to DMBA-transformed cells and confirm previous data obtained with spontaneously transformed cells.