The temporal redistribution pattern of NK cells under acute stress based on CD62L adhesion molecule expression.

Recent studies demonstrated that an acute psychological stressor elicited transient changes in lymphocyte redistribution. Earlier studies had established that CD3-CD16+CD56+ natural killer cells (NK cells) increased remarkably in peripheral blood circulation and that the amount of lymphocyte redistribution in NK cells was dependent on the CD62L expression density. Specifically, CD62L- cells were mobilized more pronouncedly than were CD62L+ cells. These results led us to hypothesize that such different reactivity causes different temporal characteristics between CD62L+ and CD62L- lymphocyte subsets. The present study was conducted to examine this issue. Ten female participants experienced a 10-minute baseline period and performed a 10-minute mental arithmetic task as an acute psychological stressor. Blood samples for measuring the proportions of CD62L+ or CD62L- NK cells and CD62L+ or CD62L- T cells were obtained immediately after each period and every 2 min during the task. As expected, CD62L+ and CD62L- NK cells showed different reactivity in response to the stressor and showed different temporal characteristics. That is, the elevation of CD62L- NK cells reached a significant level at 1 min after the initiation of the stressor, while CD62L+ NK cells took 8 min to show a tendency of elevation. Although CD3+ T cells showed different reactivity between CD62L cell types, they did not show different temporal characteristics. These findings suggest that the expression of CD62L modulates not only the amount of redistribution but also the temporal characteristics of the redistribution of NK cells.

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.

Immune, endocrine and cardiovascular responses to controllable and uncontrollable acute stress.

This study, using a triadic-yoked design, clarified the effects of controllability of acute stress on responses of immune, cardiovascular (heart rate and blood pressure), and cortisol activities. Forty-three women in their follicular phase completed a mental arithmetic task as a stressor in which controllability was manipulated by correct or yoked-bogus feedback. The task decreased proportions of CD3+ T cells, CD4+ T cells, and CD19+ B cells, whereas it increased the numbers of white blood cells, lymphocytes, natural killer (NK) cells, and NK cell activity (NKCA). Our main hypothesis that greater immune and cardiovascular responses to the task would be obtained under the uncontrollable condition than under the controllable condition was not supported. However, the uncontrollable stress condition, but not the controllable situation, led to higher correlations between heart rate or blood pressure, and various immune parameters. On the other hand, parameters of heart rate variability reflecting sympathetic and parasympathetic activities showed significant correlations only with NKCA. These results suggest that immune responses were most directly associated with cardiovascular activities under the uncontrollable condition.

Temporal variation of acute stress responses in sympathetic nervous and immune systems.

Sympathetic nervous activity plays a prominent role in acute stress responses in the immune system, enhancement of innate immunity and suppression of specific immunity. The present study was conducted to examine the temporal characteristics of such immune responses to acute stress and to determine their association with sympathetic activity in detail. For this purpose, 15 female undergraduates engaged in a continuous mental arithmetic task for 14 min, and we collected their blood samples for immune indices (CD3+ T cells, CD4+ T cells, NK cells) each 3 min during the task and saliva samples before and after the task. Our results showed that the proportion of Natural Killer cells (NK cells) increased even 2 min after initiation of the task, whereas proportions of CD3+ and CD4+ lymphocytes decreased 8 min after initiation of the task. Moreover, we found significant correlations between cardiovascular activity and the variations of immune indices.

Reactivity of immune, endocrine and cardiovascular parameters to active and passive acute stress.

This study clarified associations among immune, autonomic, and endocrine activities during mental arithmetic and cold pressor stress tasks in 26 women in the follicular phase. Both tasks decreased CD3+ T cells, CD4+ T cells, and CD19+ B cells, whereas they increased lymphocytes, granulocytes, NK cells, and NK cell activity (NKCA). The mental arithmetic task had a greater impact than the cold pressor task on changes in CD3+ T cells and in NK cells. Cardiovascular reactivity to active stress was associated with increased NK cells and decreased CD3+ T cells. Reduced cortisol levels during passive stress were associated with decreased CD19+ B cells and with increased NK cells. The merits of this study are that it controlled the following factors. Perceived stress during the two tasks was matched; both tasks lasted long enough to elicit high-magnitude responses; and the length of the intervening rest period minimized probable carryover effects between tasks.