Strain Difference and Mode of Inheritance of the Susceptibility to Passive Cutaneous Anaphylaxis Mediated by the Allogeneic IgE Antibody in the Mouse

Abstract

The strain difference and mode of inheritance of the susceptibility to PCA (passive cutaneous anaphylaxis) were studied in mice. No marked strain differences were found in the susceptibility to PCA mediated by allogeneic IgG₁ monoclonal and xenogeneic IgG antibodies, although BALB/cCrj mice were somewhat less susceptible than the other strains. On the other hand, the susceptibility to PCA mediated by allogeneic IgE monoclonal antibodies differed greatly according to the strain; SJL/J, A.SW/J and DS/Shi mice being highly susceptible and C57BL/6JShi, BALB/cCrj, DBA/2Crj, C3H/HeShi and CBA/JNCrj mice insusceptible. Based on the marked difference between DS/Shi and C3H/HeShi strains, the mode of inheritance of the susceptibility to IgE PCA was studied using their F₁, F₂ and F₁ x parent backcross offspring. All the F₁ hybrids by reciprocal crosses between these two strains and F₁ x DS backcross mice were highly susceptible like DS/Shi mice. Backcross mice between F₁ and C3H/HeShi showed approximately 1:1 segregation into the susceptible and insusceptible. Segregation was also observed in the F₂ generation; 32% being insusceptible. These results suggest that the high susceptibility is a dominant phenotype controlled mainly by a single gene on an autosomal chromosome; this was statistically supported by tests of the segregation ratios obtained. However, in the PCA-positive recipients of F₁ x C3H backcross and F₂ generations, dye leakage into the skin was tended to be diffuse and less compact than in DS/Shi, F₁ and F₁ x DS backcross mice. This suggests the presence of some additional genes which modify the expression of the main gene.