Interleukin 2 Receptor Gamma Chain (γc) Knockout Mice Show Less Regularity in Estrous Cycle but Achieve Normal Pregnancy Without Fetal Compromise

PROBLEM: Implication of cytokines in pregnancy suggested but remains to be established. We studied the effect of cytokines on reproductive functions such as ovulation and pregnancy, with mutant mice lacking interleukin 2 receptor γ (IL‐2Rγ), the so‐called common γ chain (γc), which is shared among receptors for multiple cytokines such as IL‐2, IL‐4, IL‐7, IL‐9 and IL‐15. METHOD OF STUDY: Regularities of estrous cycles were observed by vaginal smear. Ovaries stimulated with postmenopausal serum gonadotropin (PMSG) were examined for the ovarian capacities. The uteri at 13 days of gestation were used for histological analysis of the maternal–fetal interface. RESULTS: The estrous cycles in γc knockout (γc KO) mice were irregular compared with wild‐type mice, although, the mutants could become pregnant. No uterine natural killer (uNK) cell was found in the uterus at 13 days of pregnancy, and poor decidual formation and thickness of blood vessel walls were observed. Apparent differences were not seen in the numbers and weight of the fetuses between wild type and mutant animals, and fetuses were not compromised throughout pregnancy. CONCLUSIONS: The γc KO mice showed irregular estrous cycle but they could carry out normal pregnancy despite lacking uNK and cytokines actions of IL‐2, 4, 7, 9 and 15.