Fusion of Plasmacytoma and Host Cells In Vivo: Selection of Proliferating and Nonproliferating Cultures

Abstract

The double-mutant cell line 4T00.1 is derived from a plasmacytoma of a BALB/c mouse and is resistant to 6-thioguanine and ouabain. These cells were inoculated into (BALB/c × C57BL)F₁ mice by different routes—sc, ip, intrasplenically, and intrathymically. The degree of tumorigenicity and pattern of tumor development were site-dependent. Intrasplenic inoculation of 10³−10⁴ 4T00.1 cells resulted in development of large omental tumors accompanied by marked ascites. Tenfold to a thousandfold more 4T00.1 cells were required to obtain tumors by other routes. From all solid tumors and ascites and from various organs of tumor-bearing mice, which were explanted into culture in double selective medium containing hypoxanthine, aminopterin, and thymidine plus ouabain (in which only hybrids between 4T00.1 and normal cells can survive), proliferating and nonproliferating cultures were obtained. Of the 14 proliferating cultures, 9 proved to be hybrids by chromosome and H-2 isoantigen analyses and were tumorigenic when 10⁶ cells were inoculated sc into syngeneic F₁ mice.