DECIDUAL NATURAL-KILLER CYTOTOXICITY DECREASED IN NORMAL-PREGNANCY BUT NOT IN ANEMBRYONIC PREGNANCY AND RECURRENT SPONTANEOUS-ABORTION

PROBLEM: The natural killer (NK) cell activity is depressed in the dec idua of early normal pregnancy. Recently Morii et al. (Am J Reprod Imm unol 1993;29:1-4) found that all early intradecidual CD3(+) T cells ex pressed either T cell receptor (TCR) alpha/beta or gamma/delta but tha t the expression of the CD3(+)/TCR complex was down-regulated. METHOD: To test whether these changes in decidual cellular immunity are diffe rent among normal pregnancy, anembryonic pregnancy and recurrent spont aneous abortion, we examined the immune cell subpopulations in the dec idua from these three types of pregnancy using flow cytometry and an N K cytotoxicity assay. RESULTS: Intradecidual CD3(+) T cells expressed either TCR alpha/beta or gamma/delta and the level of expression of th e CD3/TCR complex was down-regulated in normal pregnancy, anembryonic pregnancy, and recurrent spontaneous abortion. Although the relative p roportion of decidual NK cells was increased to approximately the same extent in all three types of pregnancy, decidual NK activity was high er in anembryonic pregnancies and in recurrent spontaneous abortions t han it was in normal pregnancies. CONCLUSION: Decidual NK cell respons es are different in anembryonic pregnancies and in recurrent spontaneo us abortions than in normal pregnancies. Whether this difference is pa thogenic or is the response to a dead embryo remains to be elucidated.