Development and Characterization of Macrophage Hybridomas Derived from Murine Peritoneal Exudate Cells

Mouse macrophage (Mphi) hybridoma clones were generated by somatic cell hybridization of myeloma X63 cells (H-2d) with C57BL/6 (H-2b) peritoneal exudate cells elicited with a streptococcal preparation, OK432, or thioglycollate medium. Although they hardly adhered to plastic dishes and could not be morphologically distinguished from parental X63 tumor cells, the clones retained Mphi characteristics. These included phagocytosis and production of lysozyme and nonspecific esterase, suggesting that they were hybridomas derived from Mphi. Some of them expressed various levels of Ia antigen and Fc receptor. Because they induced proliferation of T cells from Balb/c mice but not those from C57BL/6 mice, the Ia antigen of Mphi hybridoma was assumed to be derived from peritoneal Mphi. The level of proliferation induction was correlated to the level of Ia antigen expression. Several clones produced a factor that cytostatically inhibited growth of murine mammary carcinoma and was serologically identified with arginine deiminase.