Natural killer cells responsiveness to physical exercise: A brief review

Abstract

Natural killer cells (NK) are a group of peripheral blood lymphocytes which display cytotoxic activity against a wide range of tumour cells. They are a consistent part of the inflammatory response that is activated when either internal or external injuries occur as they are able to synthesize perforins. An important role is played by NK cells in the host defence against tumours without expressing any antigen-binding recaptor in their membrane which, however, distinguish T and B lymphocytes. NK activity appears early in the immune response, thus providing immediate protection during the time required for the activation and proliferation of cytotoxic T lymphocytes and for their differentiation into functional cells. Even though much research regarding the effects of aerobic training exercise on NK cell numbers and function, there appears to be much controversy regarding its effect. NK cells are rapidly mobilized into circulation in response to acute exercise, most likely by increased shear stress and catecholamine-induced down-regulation of adhesion molecule expression. However, tissue injury and inflammation which often accompanies strenuous exercise have been associated to post-exercise NK cell suppression. Scientific evidence indicates exercise-induced changes in NK cell redistribution and function should be strongly influenced by stress hormones including catecholamines, cortisol and prolactin as well as by soluble mediators such as cytokines and prostaglandins. The role of exercise therapy in cancer patients and survivors rehabilitation is becoming increasingly important as it is thought to modulate immunity and inflammation. However, more knowledge about the effects of exercise on immune function in these patients is needed.

The Effects of Age and Latent Cytomegalovirus Infection on NK-Cell Phenotype and Exercise Responsiveness in Man

“…The rapid redeployment of NK-cells between the tissues and the peripheral circulation is an archetypal feature of the acute stress response. The response can be evoked using acute bouts of dynamic exercise [ 1 , 2 ], laboratory-based psychological stress tasks [ 3 ], or beta-agonist (i.e., epinephrine) infusion [ 4 ] and is often considered to be an accurate representation of an organism's ability to mount an effective immune response during fight-or-flight scenarios when tissue injury and infection are likely to occur. Acute exercise is associated with increased plasma levels of stress hormones including the catecholamines epinephrine and norepinephrine [ 5 ], which interact with β -adrenergic receptors ( β -AR) on the surface of lymphocytes.…”

Physical exercise modulates the level of serum MMP-2 and MMP-9 in patients with breast cancer

“…The mechanism underlying the health benefits of regular exercise may involve the cumulative anti-inflammatory effects of repeated physical exercise (12,13). Regular exercise promotes the synthesis of myokines that modulate the inflammatory response (14).…”

POSITIVE study: physical exercise program in non-operable lung cancer patients undergoing palliative treatment

“…However, no decline in the specific immune parameters has been reported. Recommendations refer to the increasingly important role of physical exercise in cancer patients due to the ability to modulate immunity and inflammation [ 81 ]. In this context, we expect to observe beneficial effects on immune functions caused by physical activity both after 12 weeks and after 24 weeks.…”