GLUCOSAMINYLMURAMYLDIPEPTIDE-INDUCED CHANGES IN PHENOTYPE OF MELANOMA-CELLS RESULT IN THEIR INCREASED LYSIS BY PERIPHERAL-BLOOD CELLS

Flow cytometry was used to show that biologically active N-acetylgluco samine-containing muramylpeptides (GMPs) induced in vitro dose-depende nt increase in the expression of tumor-associated antigens (TAAs) char acteristic for colon and mammary gland carcinomas, melanoma and lung a denocarcinoma. Forty to two hundred percent enhancement in TAA-express ing cells was observed after 18-48 h incubation with GMPs. In contrast , MHC class I antigen expression was not altered. Using MTT and chromi um-release assays, melanoma cells treated in vitro with GMDP were show n to be more susceptible to killing by peripheral blood cells of healt hy donors than non-treated cells. Fractionation of blood cells reveale d that platelets were responsible for this effect.