A subset of CD56+ large granular lymphocytes in first-trimester human decidua are proliferating cells

Objective: To determine whether the unusually high number of CD56+ large gr anular lymphocytes (LGL) in the decidua of early human pregnancy arises fro m selective migration or in situ proliferation. Design: Controlled clinical study. Setting: Academic research environment. Patient(s): Thirty healthy women undergoing therapeutic abortion of an inta ct pregnancy at 5-11 weeks' gestation. Intervention(s): Decidua was obtained by suction curettage; tissue and isol ated cells were subjected to immunohistochemical and flow cytometric invest igation. Main Outcome Measure(s): Proliferation rate of LGL. Result(s): The proportion of CD56+ cells positive for the proliferation-ass ociated Ki-67 antigen was found to be 7%-23.5% by three different methods o f investigation. These findings are consistent with those of how cytometric analysis of the nuclear phase, which revealed 6%-22% of the LGL nuclei to be in the phases S + G(2) + M. Conclusion(s): The various methods of investigation revealed marked prolife rative activity in the LGL of early pregnancy decidua. This finding suggest s that in situ proliferation may be responsible for the high density of the se cells in the decidua. (C) 1998 by American Society for Reproductive Medi cine.