A soluble factor which augments the expression of major histocompatibility complex class I (MHC I) antigens on a number of murine tumor cell lines, has been isolated from the culture supernatants of mixed lymphocyte reaction of spleen cells derived from C57B1/6, Balb/c and Swiss mice. The factor, termed MHC-augmenting factor (MHC-AF) has been partially purified by Sephadex G-100 column chromatography and reverse phase HPLC. MHC-AF activity is associated with an 18 kDa molecule. MHC-AF activity was resistant to pH 2.0 treatment and partially purified MHC-AF preparations did not have any activity in L929 cell/vesicular stomatitis virus (VSV) interferon bioassay system. Antibodies to IFN-gamma did not block the activity of MHC-AF. These results indicate that a MHC-AF distinct from IFN-gamma, is produced by mouse spleen cells undergoing a mixed lymphocyte reaction.
Animal ; Antibodies/pharmacology ; Chymotrypsin/metabolism ; Chymotrypsin/chemistry ; Comparative Study ; Concanavalin A/pharmacology ; Heat ; Histocompatibility Antigens Class I/metabolism* ; Histocompatibility Antigens Class I/drug effects ; Interferon Type II/pharmacology ; Interferon Type II/metabolism ; Interferon Type II/immunology ; Lymphocytes/physiology ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Proteins/pharmacology* ; Proteins/metabolism ; Proteins/isolation & purification* ; Spleen/cytology ; Trypsin/metabolism ; Trypsin/chemistry ; Tumor Cells, Cultured/immunology ; Tumor Cells, Cultured/drug effects

Mouse spleen cells activated in a mixed lymphocyte reaction release a soluble factor, which induces a significant proliferative response in fresh mouse spleen cells. This proliferation inducing factor (PIF) was found to be heat stable (90 degrees C for 45 min) and also resistant to trypsin or chymotrypsin treatment. By using a sizing HPLC column, the molecular weight of PIF appears to be 25 kDa. Mouse spleen cells treated with anti-thy-1 + complement lost Con-A induced proliferative responses but responded well to PIF. B cell depleted spleen cells obtained by negative selection panning, did not respond to PIF. These results indicate that B cells proliferated in response to PIF. Polymixin-B, which blocks the B cell proliferative response to LPS, did not inhibit PIF induced proliferation.
Animal ; B-Lymphocytes/physiology* ; B-Lymphocytes/drug effects ; Bone Marrow/metabolism ; Cell Division/physiology ; Chromatography, High Pressure Liquid ; Chymotrypsin/pharmacology ; Dose-Response Relationship, Drug ; Growth Substances/pharmacology* ; Growth Substances/chemistry ; Heat ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Molecular Weight ; Polymyxin B/pharmacology ; Protein Denaturation ; Spleen/metabolism* ; Thymus Gland/metabolism ; Trypsin/pharmacology

A novel factor which augments the expression of major histocompatibility complex I (MHC augmenting factor or MHC-AF) antigens on tumor cell lines, has been isolated from the culture supernatants of human peripheral blood mononuclear cells activated by concanavalin-A. A mouse equivalent of this factor has also been isolated from the culture supernatants of mouse spleen cells activated by mitogens or in a mixed lymphocyte reaction. Mouse MHC-AF enhances the expression of class I MHC antigens on murine tumor cell lines (EL-4 and BW5147) but not on human tumor cell lines (K562 and HR-7). Human MHC-AF on the other hand enhances the MHC I expression on both human as well as murine cell lines. Interferon gamma (IFN-gamma), a cytokine also known to enhance the expression of MHC I antigens, acts in a highly species specific manner with mouse IFN-gamma augmenting the MHC I on murine tumor cell lines and human IFN-gamma augmenting the MHC I on human tumor cell lines only. These results indicate important differences in the cross species biological activities of MHC-AF and IFN-gamma, and provide additional evidence for MHC-AF being distinct from IFN-gamma.
Animals ; Cell Line ; Cell Line, Tumor* ; Hand ; Histocompatibility Antigens Class I* ; Humans ; Interferons ; Lymphocyte Culture Test, Mixed ; Lymphocytes ; Lymphokines ; Major Histocompatibility Complex ; Mice ; Mitogens ; Species Specificity* ; Spleen

No abstract available.
Cytokines/pharmacology* ; Gene Expression Regulation ; Genes, MHC Class I* ; Histocompatibility Antigens Class I/biosynthesis* ; Interferons/pharmacology ; Lymphotoxin/pharmacology ; Models, Genetic ; Signal Transduction ; Tumor Necrosis Factor/pharmacology