MIXED LYMPHOCYTE REACTIVITY AGAINST NORMAL CELLS BY SPLENIC LYMPHOCYTES FROM TUMOR-BEARING MICE I. STUDIES OF VIGOROUS IMMUNE RESPONSIVENESS INDUCED IN F1 MICE BY PARENTAL STRAIN TUMOR CELLS

The establishment of an intimate connection between autoimmunity and neoplasia would require the demonstration of an experimentally induced, tumor-dependent autoimmune process. For this reason, we have studied cellular immune reactions of mice bearing a transplantable leukemia (L1210). Spleen cells from hybrid BDF1 mice bearing the L1210 tumor (BDFt) reacted vigorously in mixed lymphocyte culture with mitomycin-treated, normal spleen cells from mice of the parental strain from which the L1210 tumor was derived (DBA/2). Spleen cells from nontumor-bearing BDF1 mice reacted only weakly with these parental cells. The BDFt cells likewise did not respond when cultured with mitomycin-treated spleen cells from the other parental strain (C57B1/6). The vigorous mixed lymphocyte reaction (MLR) by BDFt cells against normal parental cells of the same strain as the tumor was not due to a double exposure of the reacting cells to histocompatibility antigens shared by tumor cells and normal parental cells. The response of cells from tumor-bearing F1 mice against normal parental cells seen in these experiments suggests the possibility of the induction of an autoimmune-like process against host lymphocytes by spleen cells from leukemic mice. Theoretically such a phenomenon would considerably reduce an animal's ability to mount an immune attack against malignant cells.