Cytokines: Important for implantation?

PROBLEM: Cytokines are obviously very important in an established pregnancy, but what about human embryo implantation? METHODS: Literature review. RESULTS: We first discuss the necessity and limits of animal models, and then review the few cytokines which have been demonstrated by knock-out methods to be absolutely necessary for embryo implantation using in animal models. We then review what is known or discussed about the role of other cytokines as deduced from quantitative and/or qualitative dysregulation in animals and in humans. CONCLUSIONS: Cytokines are indeed involved in implantation as they are in ongoing pregnancy and delivery. Relevance to infertility and recurrent pregnancy loss is discussed.