Interactions Between Natural Killer Cells, Cortisol and Prolactin in Malaria During Pregnancy

Abstract

Natural killer cells derived from pluripotent hematopoietic stem cells are important cells of the immune system that have two main functions: a cytolytic activity and a cytokine-producing capacity. These functions are tightly regulated by numerous activating and inhibitory receptors, including newly discovered receptors that selectively trigger the cytolytic activity in a major histocompatibility complex independent manner. Based on their defining function of spontaneous cytotoxicity without prior immunization, natural killer (NK) cells have been thought to play a critical role in immune surveillance and cancer therapy. New insights into NK cell biology have suggested their major roles in the control of infections, particularly in Plasmodium falciparum infection and in fetal implantation. P. falciparum is the main protozoan parasite responsible for malaria causing 200-300 million clinical cases and killing over 3 million people each year. This review provides an update on NK cell function, ontogeny and biology in order to better understand the role of NK cells in pregnancy in regions where malaria is endemic. Understanding mechanisms of NK cell functions may lead to novel therapeutic strategies for the treatment of human disease, in general, and particularly in the fight against malaria.

Alterations of natural killer cells in traumatic brain injury

“…The cortisol concentrations fell to borderline low values on day 3 after TBI, and the changes resembled those of NK cells. However, cortisol can suppress the immune system and directly inhibit NK cell activity, as described in some reports [35][36][37] . Therefore, we cannot yet eliminate the possibility that changes of NK cell number were the consequence of stress cortisol imbalance in our patients.…”

Relationship between hair and salivary cortisol and pregnancy in women undergoing IVF

“…With regard to the HPA-immune pathway it is well established that cortisol can regulate the activity of the immune system (Tsigos and Chrousos, 2002), including effects on the production of proinflammatory cytokines, tumour necrosis factor (TNF) and natural killer (NK) cell activity (Gatti et al 1987;Mavoungou, 2006) all of which have been implicated in reproductive outcomes (Daher et al 1999). However, the precise role of the immune system in pregnancy continues to be an area of debate.…”

Chronic steroid administration does not suppress Plasmodium development and maturation

“…The low NK cell cytotoxic activity has been postulated to correlate with the depression of cellular immune responses to P. falciparum antigens in pregnant women. Interestingly, the levels of cortisol, an adrenocortical hormone, were elevated in pregnancy, and the inhibition of NK cell functions were observed at the same time (Mavoungou 2006). Moreover, the exogenous cortisol suppressed the immune system and directly inhibited NK cell activity (Matera et al 1988).…”