GENERATION OF HUMAN CLASS-I MAJOR HISTOCOMPATIBILITY COMPLEX ACTIVATING FACTOR IN SERUM-FREE MEDIUM AND ITS PARTIAL CHARACTERIZATION

Human peripheral blood mononuclear cells (PBMCs) activated with Con-A release a soluble factor which augments the expression of class I majo r histocompatibility complex (MHC) antigens by a variety of tumour cel ls. Previous attempts to purify this factor called MHC-activating fact or (AF) (MHC-AF) made us realize that the presence of large numbers an d quantities of irrelevant fetal calf serum proteins in the culture su pernatants of the activated human PBMCs, interfered with the purificat ion procedure. It was therefore necessary to standardize the use of a serum free culture medium to generate human MHC-AF. In the present com munication we have tried several types of culture media and have ident ified DCCM-2 as the most suitable culture medium to generate human MHC -AF, MHC-AF generated in DCCM-2 medium appears to be a protein molecul e resistant to pH 2 treatment but sensitive to heat treatment (56 degr ees C x 45 min) and treatment with proteolytic enzymes trypsin and chy motrypsin.