Mammary carcinoma arising in mice undergoing a chronic graft-versus-host reaction

A graft-versus-host reaction (GVHR) was induced in 30 (CBA X A)F1 mice by the iv injection of 50 X 10(6) parental strain A lymphoid cells. Solid tumors emerged in 5 of 10 experimental animals that survived beyond 14 months after the GVHR was initiated. The neoplasms were judged to be mammary carcinomas by light and electron microscopic examinations. C-type RNA viral structures were observed in some tumor cells. The neoplasms were successfully transplanted into syngeneic animals by either sc or ip injections of tumor cell suspensions. Tumor transfer to syngeneic mice was not possible if only spleen cells from tumor-bearing animals were transferred. No tumors developed in an age-matched control group that received no treatment.