Parabiosis between avian embryos selected for high and low competences of the graft-versus-host reaction.

Parabiosis of chicken embryos was conducted to determine if changes in immunological competences could occur by parabiosis between lines of chickens selected for high (H) and low (L) graft-versus-host reaction (GVHR). Eggs of the B9B9 genotype from the H line (H-B9B9) were parabiosed to eggs of the B11B11 from the L line (L-B11B11) and also the H-B11B11 were parabiosed to the L-B9B9. There were significant differences in hatchability between the line-genotype groups. The percentage of blood chimerism of parabionts showed also significant genetic differences. Chimerism was the highest in the H-B11B11 birds and the lowest in the L-B11B11. All chimeric parabionts showed immunological tolerance and almost all nonchimeric parabionts did not. Immunological competence was measured by splenomegaly index (SI) based on GVHR. The SI value of parabionts changed in the direction of the SI value of the partner. The SI value of chimeric parabionts differed significantly from those of nonchimeric parabionts and controls. Antibody response to bovine serum albumin was tested only for the H-B11B11. Antibody titers of parabionts were significantly lower than those of controls.