Fetal loss due to Th1-skewed Th1/Th2 balance with increase (not decrease) of regulatory T cells in abortion-prone mouse model.

We used an abortion-prone mouse model, generated by mating female CBA/J mice with male DBA/2JJcl mice, to examine the effects of changes in the Th1/Th2 cell ratio and the percentage of regulatory T (Treg) cells on the maintenance of pregnancy. We subcutaneously injected female CBA/J mice once each with 50 μg/mouse of Dermatophagoides farinae (Df) extract and the squalene-based adjuvant (SquA); 10 days later, these mice were mated with male DBA/2JJcl mice. Compared with injection of vehicle or adjuvant, the Df treatment decreased the Th1/Th2 cell ratio and concomitantly increased the percentage of Treg cells in the spleen.