T lymphocytes of allophenic mice do not reject spleen colony-forming units of the parental genotypes.

Self-tolerance in BALB/c<-->C57BL/6 and BALB/c<-->B10.SM (SM) allophenic mice is examined in this study. Chimerism was determined by coat mosaicism, using electrophoresis of allozyme variants at the glucose phosphate isomerase-1 (GPI-1) in peripheral blood erythrocytes and a cytotoxity test for lymph node (LN) lymphocytes and blood nucleated cells. An age-dependent increase in the percent content of BALB/c erythrocytes was observed in both types of chimeras. The immunological status of chimeras was assessed by T cell interactions with spleen colony-forming cells (SFU-S) able to form colonies in the recipient spleens. LN lymphocytes of the chimeras, together with bone marrow cells (BMC) of the parental genotype, were transplanted to lethally irradiated F1 hybrids. Chimera T lymphocytes did not inactivate CFU-S of the parental genotype and colonies formed in the spleens of F1 hybrids. The absence of splenic colonies in (C x B6)F1 hybrids, in which BMC from B6 had been transplanted (either in combination with chimera lymphocytes or alone), was due to the reaction of host natural killer (NK) cells. The results obtained testify to the permanent immunological tolerance of chimera T lymphocytes to BMC antigens of the both parental genotypes. The chimeric shift in the erythrocyte population is not coupled to disturbances in self-tolerance of chimeric mice.