The response of human decidual leukocytes to IL-2

The phenotype of human decidual leukocytes, composed predominantly of CD3-CD16(-)-CD56bright cells, was examined after culture with IL-2 by immunofluorescence and flow cytometry. After IL-2 stimulation the phenotype became like that found on classical NK cells, with an increased proportion of cells expressing CD16. The IL-2R alpha was absent before and after IL-2 stimulation. However, the intermediate affinity receptor, IL-2R beta, was expressed by CD56bright decidual cells, but this receptor was downregulated after IL-2 stimulation. IL-2-induced proliferation of CD56+ decidual cells could be blocked using TU27, a monoclonal antibody to the IL-2R beta. These findings indicate activation of decidual leukocytes by IL-2 occurs through the IL-2R beta alone.