A transplantable immunocytoma of the rat as a model for the study of immunoglobulin secretion

An immunoglobulin secreting tumor appeared spontaneouldy in the LOU/Dec rat strain in an incidence of about 3--5% at age 8-20 months. Attempts to increase the incidence using such things as genetic selection, carcinogens, immunosuppressants, adjuvants, cell-free fumor material, and antigenic stimulation were unsuccessful. The tumor was found to be easily transplanted. It secreted monocolonal immunoglobulins related to most of the normal rat immunoglobulins: IgG, IgA, IgM, IgE, and some light chains. Some tumor lines were found to be sensitive to chemotherapy. Tumor-bearing rats, cured by chemotherapy, were found to be resistant to subsequent challenge graft of the tumor. The resistant state could be transferred from one animal to another by parabiosis or peritoneal exudate, but not by way of serum. It was concluded that the tumor-bearing LOU/Dec rat is an excellent model for studies of immunoglobulin secretion, and the cured, resistant rat is an excellent model for studies of cell mediated immunity.