Immunological Correlation of Several Neurogenic Tumors and Mammary Carcinoma in a Syngeneic Rat System

Immunological cross-reactivities between rat spontaneous mammary carcinoma or ethylnitrosourea (ENU)-induced neurogenic tumors and various fetal and adult tissues were tested in vitro by the migration inhibition test (MIT). Wistar/Fib rats were immunized with either live cells or radiation-killed tumor cells of over 37 transplant generations. ENU-induced neurinomas of the peripheral nerve (T1, T3) lost some of their antigenicities in the later transplantation generations, and failed to react with fetal or brain tissues. On the other hand, ENU-induced oligodendroglioma (T5) retained strong antigenicities at least up to the 10th passage. In addition, T5 and syngeneic spontaneous mammary carcinoma (T9) showed similar responses to fetal extracts. Among the tissues examined, two-week fetal tissues showed the highest expression of fetal antigens detected by cross-reaction with these tumor cells. MIT with 3M KG extracts of fetal tissues demonstrated that sensitization with live tumor cells elicited stronger immunological responses than that with radiationkilled cells.