Tolerance of F1 Hybrid Skin Homografts in the Parent Strain Induced by Parabiosis.

1) Tolerance of F1 hybrid skin homografts in mice of their corresponding parent strains has been attempted by establishing “F1 to parent” parabiosis. 2) Results were: a) Mice of either Z or Ce strain joined in parabiosis with (Z x Ce) F1 hybrids became tolerant and accepted skin homografts taken from this hybrid. b) Tolerance of (A x Z)Fi skin was also obtained in Z strain mice following parabiosis with (A x Z)F1 hybrids. However, A mice joined to the same hybrids failed to develop tolerance and rejected the F1 grafts in all instances, c) While 20% of Z mice became tolerant of (Z x C57 Bl)F1 skin after being in parabiosis with this hybrid, none of C57Bl parent parabionts were susceptible of the hybrid skin grafts.