Maternal lymphocyte subpopulations (CD45RA+ and CD45RO+) in preeclampsia

Objective: The maternal syndrome of preeclampsia has been attributed to a systemic intravascular inflammatory response and endothelial cell dysfunction. The stimulus responsible for intravascular inflammation in preeclampsia has not been determined. The expression of CD45 isoforms on the surface of human T cells has been used to classify CD4+ T lymphocytes into naı̈ve cells (CD45RA+) and memory T cells (CD45RO+). An increased percentage of CD45RO+ cells has been interpreted as consistent with previous exposure to microbial products or other antigens. The purpose of this study was to determine whether preeclampsia is associated with a change in the proportion of CD45RA+ and CD45RO+. Study Design: A prospective study was conducted in patients with preeclampsia (n = 24) and normal pregnancy (n = 75). The percentage of CD45RA+ and CD45RO+ on CD4+ T lymphocytes in peripheral blood was determined using flow cytometry and monoclonal antibodies. Results were reported as a percentage of CD4+ lymphocytes. Parametric statistics were used for analysis. A probability value of <.05 was considered statistically significant. Results: Patients with preeclampsia had a significantly higher percentage of CD45RO+ than normal pregnant women (P< .01). A significantly lower percentage of CD45RA+ was found in patients with preeclampsia than in normal pregnant women (P< .01). Conclusion: Preeclampsia is associated with an increase in the percentage of CD45RO+ and a decrease in the CD45RA+ lymphocyte subpopulation. Therefore, patients with preeclampsia have evidence of previous antigenic exposure, the nature of which remains to be established. (Am J Obstet Gynecol 2002;187:889-93.)