Are adhesion molecules involved in stress-induced changes in lymphocyte distribution?

Acute psychological stress is associated with important changes in circulat ing cell populations and reductions in cell-mediated immune responses. Howe ver, the mechanisms underlying these phenomena are poorly understood. In th is study, we investigated (i) acute and chronic restraint stress effects in Sprague-Dawley rats on peripheral lymphocyte subsets and (ii) adhesion mol ecule (beta2 integrins) expression and (iii) also determined whether glucoc orticoids could underlie stress-related changes in cellular redistribution. We observed time-dependent changes in lymphocyte distribution including de creased (-21%) percentages of peripheral T helper cells and increased (88%) NK cell numbers following acute brief restraint. Acute stress was also fou nd to overall upregulate beta2-integrin (CD I I a and CD11b) expression on T cells and to raise (1049%) plasma corticosterone levels. However, this st ress response was found habituated (-75% vs. acute) in the animals previous ly exposed to chronic restraint stress. Stress effects on circulating lymph ocytes were not observed in animals previously exposed to chronic intermitt ent restraint stress or chronically stressed animals re-exposed to the same stressor. Our results indicate that 1) stress alters lymphocyte distributi on, 2) that adhesion molecules may be involved in stress-induced alteration s of T-cell distribution and 3) that these changes may be related to circul ating glucocorticoids and subjected to adaptation with repeated stress expo sure. (C) 2001 Elsevier Science Inc. All rights reserved.