Part E: The Role of Cytotoxic Natural Killer (NK) Cells and Regulatory NK Cells in Pregnancy

Author(s): Shigeru Saito, Tomoko Shima, Akitoshi Nakashima and Yi Lin

Pp: 578-591 (14)

* (Excluding Mailing and Handling)

Abstract

During the early phases of pregnancy, natural killer (NK) cells are the predominant lymphoid cells in the uterus. Uterine NK (uNK; decidual NK) cells contribute to vascular formation and placentation, and play an important role in induction of tolerance toward the fetus allograft by interaction with regulatory T (Treg) cells, dendritic cells (DCs) and CD14⁺ monocytic cells.

On the other hand, uNK cells have been shown to induce abortion by attacking the fetus or Placenta.We propose that CD25⁺IL-10⁺NK cells play a pivotal role in successful pregnancy and granulysin⁺ NK cells attack extra-villous trophoblasts (EVTs), causing their death due to apoptosis. A deeper understanding of the balance between cytotoxic NK cells and regulatory NK cells during pregnancy may increase understanding of normal pregnancy and complicated pregnancy.

Keywords: Natural killer (NK) cells, uterine NK cells, regulatory T (Treg) cells, NK cells, cytotoxic NK cells, regulatory NK cells, normal pregnancy, complicated pregnancy, Toll-like receptors (TLRs), CD16-CD56^brightNK cells, Granulysin, indoleamine 2, 3-dioxygenase (IDO), CLTA-4, thymic stromal lymphopoietin (TSLP), unexplained recurrent miscarriage patients.