ABSTRACT
BACKGROUND: The group-specific component protein-derived macrophage-activating factor (GcMAF) has various biological activities, such as macrophage activation and antitumor activity. Clinical trials of GcMAF have been carried out for metastatic breast cancer, prostate cancer, and metastatic colorectal cancer. In this study, despite the complicated purification process of GcMAF, we used enzymatically-treated human serum containing GcMAF with a considerable macrophage-stimulating activity and antitumor activity. RESULTS: We detected GcMAF in degalactosylated/desialylated human serum by western blotting using an anti-human Gc globulin antibody, and Helix pomatia agglutinin lectin. We also found that GcMAF-containing human serum significantly enhanced the phagocytic activity of mouse peritoneal macrophages and extended the survival time of mice bearing Ehrlich ascites tumors. CONCLUSION: We demonstrated that GcMAF-containing human serum can be used as a potential macrophage activator for cancer immunotherapy.
Subject(s)
Carcinoma, Ehrlich Tumor/prevention & control , Galactose/metabolism , Macrophage Activation/drug effects , Macrophage-Activating Factors/pharmacology , Macrophages, Peritoneal/drug effects , Phagocytosis/drug effects , Serum/chemistry , Sialic Acids/metabolism , Vitamin D-Binding Protein/pharmacology , Animals , Blotting, Western , Carcinoma, Ehrlich Tumor/metabolism , Carcinoma, Ehrlich Tumor/pathology , Female , Humans , Macrophages, Peritoneal/cytology , Macrophages, Peritoneal/metabolism , Mice , Mice, Inbred ICRABSTRACT
BACKGROUND: The 1f1f subtype of the group-specific component (Gc) protein is converted into Gc protein-derived macrophage-activating factor (GcMAF) by enzymatic processing with ß-galactosidase and sialidase. We previously demonstrated that preGc(1f1f)MAF, a full Gc(1f1f) protein otherwise lacking a galactosyl moiety, can be converted to GcMAF by treatment with mouse peritoneal fluid. Here, we investigated the effects of the ß-galactosidase-treated 1s1s and 22 subtypes of Gc protein (preGc(1s1s)MAF and preGc22MAF) on the phagocytic activation of mouse peritoneal macrophages. RESULTS: We demonstrated the presence of Gal-GalNAc disaccharide sugar structures in the Gc(1s1s) protein by western blotting using peanut agglutinin and Helix pomatia agglutinin lectin. We also found that preGc(1s1s)MAF and preGc22MAF significantly enhanced the phagocytic activity of mouse peritoneal macrophages in the presence and absence of mouse peritoneal fluid. CONCLUSION: We demonstrate that preGc(1s1s)MAF and preGc22MAF proteins can be used as effective macrophage activators.
