Influence of radiation field and fractionation schedule of total lymphoid irradiation (TLI) on the induction of suppressor cells and stable chimerism after bone marrow transplantation in mice.
When BALB/c mice received 17 daily fractions of 2 Gy each of total lymphoid irradiation (TLI, total dose 34 Gy) and 30 X 10(6) C57 B1 bone marrow cells (BM) on the day after the last fraction, stable bone marrow chimerism without signs of graft-vs-host disease (GVHD) was obtained in 84% of the animals. On the contrary, in BALB/c mice receiving only seven fractions of TLI (total dose 14 Gy), all bone marrow grafts were rejected. When the last two fractions of a 14-Gy TLI course were given without shielding the extra lymphatic tissues (combined total lymphoid + total body irradiation, TLBI), chimerism could be induced in 53% of the animals. When this 14-Gy TLBI schedule was used, it was even possible to administer four fractions per day (multiple fractions per day schedule, MFD), thus reducing the overall treatment time to 2 consecutive days. After this concentrated form of TLBI, chimerism was detected in 35% of the animals. As in the 34-Gy TLI schedule, graft-vs-host reaction could not be prevented in the 14-Gy TLBI schedule when spleen lymphocytes (10 X 10(6) were added to the BM inoculum. Leucopenia or suppression of the phytohaemagglutinin (PHA)-induced blastogenesis could not predict which schedule would result in a successful allogeneic bone marrow take. Suppressor cells of the mixed lymphocyte reaction, on the other hand, were only found in the spleen of BALB/c mice treated with the TLI or TLBI schedules, which also resulted in stable bone marrow chimerism.
D000818:Animals; D016026:Bone Marrow Transplantation; D006086:Graft vs Host Disease / Q000401:mortality / Q000532:radiotherapy; D007964:Leukocytosis / Q000209:etiology; D008213:Lymphocyte Activation / Q000528:radiation effects; D008221:Lymphoid Tissue / Q000528:radiation effects*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011828:Radiation Chimera; D013154:Spleen / Q000166:cytology / Q000528:radiation effects; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000528:radiation effects; D014916:Whole-Body Irradiation / Q000009:adverse effects / Q000379:methods*