Evidence for Immunization of F 1 Hybrid Mice Against Parental Transplantation Antigens

Summary

1. Previous grafting of parental spleen cells or skin accentuated secondary disease in F₁ hybrid mice subsequently irradiated and inoculated with marrow from donors of the same parental strain. 2. The intensity of the effect varied in relation to the extent of H-2 histocompatibility differences among the 4 strain combinations tested. 3. The effect is ascribed to “immunization” of the F₁ hybrid against parental tissue antigens. It is, therefore, inferred that parental histocompatibility alleles may not necessarily be expressed as codominants in F₁ hybrid mice.

Addendum. After submission of the manuscript, additional experiments showed that when the CAF₁ hybrid was “immunized” against A spleen cells by three, instead of two, inoculations at 30, 20, and 10 days prior to marrow grafting, respectively, secondary mortality i.e., between 20–90 days) was enhanced to an extent comparable with that noted in the other strain combinations tested. However, the same treatment with BALB/c cells was not followed by increased secondary mortality. These results indicate, therefore, that A strain parental tissues are also capable of “immunizing” F₁ hybrid mice.