title: Loss of marrow allograft resistance in mice with transplanted methylcholanthrene-induced sarcomas.
abstract: To determine if the effector cells responsible for allogeneic marrow stem cell rejections were suppressed in mice with tumors, C57BL/6 (B6) mice were inoculated with 3-methylcholanthrene (MCA)-induced sarcoma cells. When the tumor reached 2.0--2.5 cm in diameter, these mice and control B6 and (BALB/c times A)F1 (CAF1) uninoculated animals were irradiated and given BALB/c marrow cells in the first of a two-step "stem cell rescue" experiment. Four days later, spleen cells of the primary hosts were reinoculated into irradiated CAF1 secondary hosts compatible with BALB/c marrow cells and immunized against B6 antigens. Splenic uptake (percent) of 125I-5-iodo-2'-deoxyuridine 5 days after spleen cell regrafting was used as a measure of cell proliferation and reflected growth of the stem cells in the primary hosts. BALB/c stem cells grew as well in B6 mice with tumors as in CAF1 primary hosts but were rejected by B6 controls. Seeding efficiency of BALB/c stem cells 6 hours after infusion of marrow cells and growth of syngeneic B6 stem cells were enhanced twofold in spleens of tumor-bearing B6 mice. To exclude the possibility that enhanced seeding resulted in greater survival of allogeneic stem cells, more DBA/2 marrow cells were infused into control B6 primary hosts than into tumor-bearing B6 and control DBA/2 mice. Control B6 mice resisted growth of even 7.5 times 10(6) DBA/2 marrow cells, whereas B6 tumor bearers allowed growth of 2.5 times 10(6) cells. No "suppressor cells" capable of inhibiting marrow cell allograft reactions were detected in spleens of tumor-bearing mice. Thus transplanted syngeneic MCA-induced sarcomas abrogated the ability of mice to reject allogeneic marrow stem cells.
mesh_terms: D000818:Animals; D006084:Graft Rejection; D018380:Hematopoietic Stem Cell Transplantation; D007065:Idoxuridine / Q000378:metabolism; D008297:Male; D008748:Methylcholanthrene; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009368:Neoplasm Transplantation; D012513:Sarcoma, Experimental / Q000139:chemically induced / Q000276:immunology*; D013154:Spleen / Q000276:immunology / Q000378:metabolism; D014184:Transplantation, Homologous
chemical_list: D008748:Methylcholanthrene; D007065:Idoxuridine