Peripheral K cells in normal human pregnancy: decrease during pregnancy and increase after delivery

Abstract

Peripheral blood levels of K cells were measured in normal pregnant and postpartum women by a plaque-forming cell technique that detects K cells on the basis of their activity of antibody-dependent cell-mediated cytotoxicity (ADCC). Peripheral K cells decreased throughout normal pregnancy ( n = 46; 7.8 ± 3.4%, P < 0.01; 0.13 ± 0.08 × 10 9/1, P < 0.001) and increased in the post-partum period ( n = 17; 14.2 ± 6.1%, P < 0.05; 0.32 ± 0.20 × 10 9/1, P < 0.01) in comparison with those in normal non-pregnant controls ( n = 29; 10.5 ± 4.2%; 0.20 ± 0.09 × 10 9/1). These findings suggest that a decrease of K cells during pregnancy may contribute in part to maternal acceptance of the fetal allograft and that the post-partum increase of K cells may represent a post-partum increase of cell-mediated cytotoxicity, which may contribute to natural defense against puerperal infection.