Suppression of Natural Killer Cell Cytotoxicity in Postpartum Women

Abstract

Little is known about the recovery of the immune system from normal pregnancy and whether the postpartum period is a uniquely adapted immune state. This report extends previous observations from our group of decreased natural killer (NK) cell cytotoxicity in the postpartum period. NK cytotoxicity was measured from 1 week through 9 months postpartum. In addition, NK cytotoxicity was assayed in the presence or absence of pooled plasmas collected from either postpartum or nonpostpartum women. Samples of cells were stained for inhibitory receptors and analyzed by flow cytometry. NK cytotoxicity remained decreased in postpartum women compared to controls through the first 6 postpartum months, returned to normal levels by 9 months and remained normal at 12 months. NK cytotoxicity during the first 6 months was further inhibited by the addition of pooled plasma to NK cultures from postpartum women, but the addition of pooled plasma from the control group did not affect that group’s NK cultures. There were differences in inhibitory receptor staining between the two groups, with decreased CD158a and CD158b and increased NKG2A expression on postpartum NK cells during the first 3 postpartum months. These data suggest that NK cytotoxicity postpartum inhibition lasts 6 months and is influenced by unidentified postpartum plasma components. The effect may also involve receptors on NK cells.

Natural killer cell activity irreversibly decreases after Cryptosporidium gastroenteritis in neonatal mice

“…The other methods, including 51 Cr assay, operate with a high effector-target ratio (of 50:1, 100:1 and even 400:1 and more). 27,28 Also, 3 H-uridine cytotoxic test demonstrates no spontaneous release of this isotope from cells, in contrast to 51 Cr with spontaneous release of about 20%. [29][30][31] All these advantages of 3 H-uridine assay over 51 Cr assay prompted us to apply this simple and accurate test to obtain the reliable data.…”

“…3 H‐uridine assay enables to use the ratio of cell effectors to targets as low as 20:1 giving opportunity to conduct as many as 6‐8 repeats per neonatal mice. The other methods, including 51 Cr assay, operate with a high effector‐target ratio (of 50:1, 100:1 and even 400:1 and more) . Also, 3 H‐uridine cytotoxic test demonstrates no spontaneous release of this isotope from cells, in contrast to 51 Cr with spontaneous release of about 20% .…”

Hemophagocytic Lymphohistiocytosis during the Postpartum Stage of Pregnancy: A Report of Eight Cases

“…In addition to a possible sustained T cell immunomodulation disorder from pregnancy, the suppression of NK cell cytotoxicity during the postpartum period may also contribute to HLH. One study determined that NKG2A was markedly increased in postpartum women [14]. NKG2A is an inhibitor of NK cytotoxicity and has been considered as being related to HLH in the recent literature.…”

Immune Changes and Dysphoric Moods Across the Postpartum

“…Return to a “normal” prepregnant immune state is not well characterized and may take as long as one year after the birth 6 . Natural Killer cell cytotoxicity, suppressed during pregnancy, remains suppressed for over 6 months in postpartum women 7 . T cells expressing the CXCR3 or CCR4 marker, CD4+CD25+ cells (T regs) and HLA-DR+ cells increase across the postpartum.…”

“…6 Natural Killer cell cytotoxicity, suppressed during pregnancy, remains suppressed for over 6 months in postpartum women. 7 T cells expressing the CXCR3 or CCR4 marker, CD4 + CD25 + cells (T regs), and HLA-DR + cells increase across the postpartum. 8 The interactions of immunology and behavioral phenomena (moods and stress) are also important to understand, as the postpartum is a stressful time of adjustment for women and is also characterized by higher than normal levels of depression and fatigue.…”