Influence of thermal stress on lymphocyte migration pattern in rats

In order to study an influence of thermal stress on lymphocyte migration, isotope-labelled lymphocytes, harvested from syngeneic donor rats, were injected intravenously into recipients, thus mimicking the traffic of autogeneic lymphocytes. Corticosterone, adrenaline and noradrenaline serum levels and hemodynamic parameters were measured in stressed and control rats. In thermal-stressed rats significantly less lymphocytes could be found in the spleen, mesenteric and peripheral lymph nodes. In contrary, a significant increase of lymphocyte quantity in the bone marrow of limbs and spine was observed. There was a tendency of lymphocytes to migrate to the dorsal and hypogastric skin of stressed animals. The change in lymphocyte traffic was accompanied by an increase in serum corticosterone and a decrease in serum noradrenaline. Although no direct cause and effect-relationship between hypercorticosteronemia and redistribution of migrating lymphocytes was found, the obtained data and review of pertinent literature are highly suggestive of a functional link of both observations.