K-cell activity is enhanced intrapartum

The cytotoxic activity of killer (K)-cells was measured against O Rh(D)-positive human erythrocytes sensitized by anti-D antibodies, in 14 women during normal labor and compared with the K-cell activity of 20 pregnant women (in the 37-40th week of pregnancy) and 42 non-pregnant female controls. K-cell activity was determined by the enzyme-like kinetic cytotoxic model, which measured the maximum of killing capacity. Cytotoxic activity was found to be significantly higher intrapartum. Data are compatible with the possibility that immunologic mechanism(s) are contributing to the onset of parturition.