Increased soluble human leukocyte antigen-G levels in peripheral blood from climbers on Mount Everest.

Soluble human leukocyte antigen-G (HLA-G) is involved in maternal-fetal tolerance, transplant acceptance, and tumor escape from immunosurveillance, operating by inhibiting activity of T, antigen presenting cells (APC), and natural killer (NK) cells. HLA-G gene expression is modulated in vitro after hypoxic conditions, a situation evidenced during pregnancy and tumor progression. In extreme altitude, mountaineers are in hypoxic conditions that generate physiologic adaptative responses, some of them giving rise to pathologic signs.