Abstract
Changes in numbers of peripheral blood lymphocytes from healthy individuals were calculated from samples collected before and after parenteral administration of adrenaline, insulin and hydrocortisone, respectively. A marked increase in circulating lymphocytes was noted in response to adrenaline and insulin. However, subpopulation analysis showed a decrease in the proportion of T-lymphocytes, estimated as cells forming rosettes with sheep red blood cells after incubation in the cold and a corresponding increase in proportion of lymphocytes having receptors for C3 (non-T lymphocytes). In contrast, lymphocyte numbers were unaffected by hydrocortisone. The results indicate that a decreased proportion of circulating T-lymphocytes and an increase of non-T lymphocytes may be the result of adaptive changes in response to various forms of stress and hence is to be expected in several clinical conditions.