Tumor Formation and Paraprotein Production by Mouse Plasmacytoma Cells Transplanted to Hamsters

Abstract

A suspension of cells from a BALB/c mouse MPC-11 plasmacytoma was transplanted into the cheek pouches of 51 irradiated and 50 nonirradiated hamsters. Forty-two of the irradiated and 29 of the nonirradiated animals took the graft. The irradiated hamsters were sacrificed, at the latest, 15 days and the nonirradiated ones 21 days after the transfer. By that time, the animals had developed large tumors and showed no signs of rejection. The tumors grew as well in the nonirradiated as in the irradiated animals. Histologic examination of the injection sites revealed infiltration of the areolar tissue with tumor cells of different sizes, many of which were undergoing mitotic division. By immunocytochemical techniques we showed that the tumor cells produce a γ-2b globulin identical with that found in mice carrying this tumor. This protein was also present in the peripheral blood of the tumor-bearing hamsters. Being a privileged site, the hamster's cheek pouch can serve well as a growth-sustaining environment for a heterologous mouse plasmacytoma. Because the mouse MPC-11 plasmacytoma remains viable and synthesizes a specific paraprotein for at least 21 days after implantation in the cheek pouch of normal hamsters, we are able to use this experimental model to study the effects of the continued presence of a foreign undenaturated protein on an immunologically competent host.