Regulation of lymphocytes redistribution via autonomic nervous activity during stochastic learning.

Several studies reported that redistribution of lymphocyte subsets, especially CD3-CD16+CD56+ natural killer (NK) cells, was elicited by acute psychological stress tasks. It is known that lymphocyte redistribution was regulated based on active or passive emotional coping strategies, which can be elicited dependent on controllability of a stressor. Controllability can be evaluated gradually by learning of a contingency between actions and outcomes. Therefore, lymphocyte redistribution can be determined by learning of the contingency. To examine this issue, we used a stochastic learning task as an acute stress task and divided twenty healthy participants into reinforcement or yoked groups. Between the two groups, only whether they could learn the contingency was manipulated. As a result, patterns of changes in the NK cell numbers differed between the groups; NK cells remarkably increased at first and then gradually decreased to the baseline in the reinforcement group while the yoked group showed a moderate but sustained increase of NK cells. These patterns of changes in the NK cells were completely parallel with changes of the cardiovascular parameters but not with secretion of catecholamines. The present results suggest that cardiovascular and immune reactivity can be modulated along with progresses of adaptation for an acute stressor.