Conditioned increase of natural killer cell activity (NKCA) in humans.

Abstract

Cumulating evidence suggests that immune parameters can be modified by behavioral conditioning processes in animals. The present results suggest that this also holds true for a human immune parameter. Healthy subjects were exposed to a conditioning procedure in which a neutral sherbet sweet (conditioned stimulus) was repeatedly paired with a subcutaneous injection of 0.2 mg epinephrine (unconditioned stimulus). After epinephrine administration an increase of natural killer (NK) cell activity could be observed (unconditioned response). On the conditioning test day the conditioned group showed increased NK cell activity after reexposure of the sherbet sweet combined with saline injection. No increase was found in control groups that previously received the sherbet sweet in combination with saline (saline control) or with epinephrine in an unpaired manner (unpaired control). This study supports previous findings of conditioned modulation of immune responses and represents a model to investigate conditioning processes of a human immune function.

Conditioning Immune and Endocrine Parameters in Humans: A Systematic Review

“…Eleven of the 16 studies were aimed at conditioning of immune functions (69%) and 5 studies were aimed at conditioning of endocrine functions (31%). Concerning the studies on conditioning of immune functions, 5 studies addressed conditioned immunosuppression (31% of all studies) [19][20][21][22][23] , 3 studies addressed conditioned immunostimulation (19%) [24][25][26] , and 3 studies addressed conditioned allergic responses (19%) [9,27,28] . Of the studies on conditioning of endocrine outcomes, 4 (25%) addressed conditioned glycemic responses [29][30][31][32] and the remaining study addressed conditioned cortisol (6%) [33] .…”

“…Regarding the general conditioning paradigm, all but one [26] of the studies (94%) [9,[19][20][21][22][23][24][25][27][28][29][30][31][32][33] employed a design with an acquisition phase, in which the UCS was repeatedly paired with the CS, and an evocation phase, in which the CS was presented together with a placebo. The remaining study on immunostimulation employed an intermittent treatment schedule in which the CS was consistently paired with the UCS in the first phase of the study (acquisition phase) and was administered intermittently with or without the UCS in the second phase of the study [26] .…”

“…The participants in 13 studies were healthy volunteers (81%) [19][20][21][22][23][24][25][26][29][30][31][32][33] , whereas 3 studies (19%) included participants who were allergic to either pollen [27] or house dust mites [9,28] .…”

“…Two studies (13%) did not provide information on the age of the participants [24,27] . Concerning the gender of the participants, 10 studies (63%) included only male participants [19-23, 25, 29, 30, 32, 33] , while 1 study included only female participants (6%) [31] and 3 studies (19%) included male as well as female participants [9,26,28] (60% female [9,26] and 76% female [28] ).…”

“…Concerning the gender of the participants, 10 studies (63%) included only male participants [19-23, 25, 29, 30, 32, 33] , while 1 study included only female participants (6%) [31] and 3 studies (19%) included male as well as female participants [9,26,28] (60% female [9,26] and 76% female [28] ). The 2 remaining studies (13%) did not report the gender of the participants [24,27] .…”