Reproduction in mice lacking a functional type 1 IL-1 receptor

Growth factors and cytokines have been identified in having critical roles at mediating maternal-fetal interactions during pregnancy, with interleukin-1 being a recently implicated factor. Previous experiments indicated that repeated intraperitoneal injections of the Il-1 receptor antagonist (Il-1Ra), which inhibits binding of interleukin-1 (Il-1) to the type 1 Il-1 receptor (Il-1Rt1) blocks blastocyst implantation in superovulated mice, To, gain a greater insight into the role of Il-1 and type 1 Il-1 receptor in implantation, we analyzed the reproduction of mice deficient for the Il-1Rt1. Our results show that mice lacking this receptor do not exhibit any profound alterations in their reproduction, apart from a slight reduction in mean litter size. Furthermore, repeated intraperitoneal injections of either IL-1Ra or the monoclonal antibody 35F5, which also blocks ligand binding to the Il-1Rt1, did not affect embryo implantation in either wild type and Il-1 receptor deficient mice.