PROBLEM The purpose of this study is to clarify whether IL-2 expressed in the decidua in preeclampsia affects the angiogenesis of the placenta. METHOD OF STUDY We investigated the angiogenic substances released from human trophoblasts obtained from early pregnancy that had been pretreated with either IL-2, non-activated lymphocytes from peripheral blood mononuclear cells (PBMCs), decidual lymphocytes, or these lymphocytes activated by lymphokine (LAK cells). Angiogenic activity was determined by evaluating the ability of growth-promotion of cultured human microvascular endothelial cells (HMvECs) using MTT assay. RESULTS Trophoblasts pretreated with IL-2 or non-activated lymphocytes, irrespective of their origin, released angiogenic factor similar to those without pretreatment. However, trophoblasts pretreated with LAK cells released less angiogenic factor compared with those without pretreatment. CONCLUSIONS Interleukin-2 (IL-2) expressed in preeclamptic decidua might reduce the angiogenic substances arising from trophoblasts by inducing LAK-cells from decidual lymphocytes, which might be relevant to deranged vasculature of the placenta, a characteristic histology in preeclampsia.