ADRENALINE-INDUCED LEUKOCYTOSIS - RECRUITMENT OF BLOOD-CELLS FROM RATSPLEEN, BONE-MARROW AND LYMPHATICS

It is well known that adrenaline causes leucocytosis, but the sources and the mechanisms of this have not been clarified. We investigated th e contributions of subpopulations of white blood cells to this leucocy tosis and the importance of the spleen, bone marrow and lymphatics in releasing leucocytes into the blood stream following an injection of a drenaline. We studied possible effects of adrenaline on blood flow to the spleen and bone marrow to see if any contribution to leucocytosis from these organs could be perfusion dependent. In intact awake rats, total blood leucocytes increased within 5 min to about 220% of baselin e concentration, the increases of lymphocytes and neutrophilic granulo cytes being about 250% and 160%, respectively. The T and B lymphocytes and natural killer cells were all mobilized, to about 230% to 250% of baseline concentrations. The leucocytosis was short-lasting, so that the cell concentrations returned to baseline within 25 min after adren aline injection. The bone marrow, spleen, and efferent lymphatics all contributed substantially to this leucocytosis, since band-nucleated g ranulocytes increased upon adrenaline injection, and splenectomized or thoracic duct drained rats showed a markedly reduced leucocytosis in response to adrenaline. Supplementary data were obtained with bone mar row depleted (with Sr-89 irradiation) rats. The release of leucocytes from these organs was apparently not blood-flow dependent in the contr ol rats since organ perfusion remained unaltered after adrenaline inje ction. Adrenaline was found to stimulate the release of both mono- and polymorphonuclear cells in the awake rat and the release of leucocyte s from the spleen, bone marrow and efferent lymphatics to contribute s ignificantly to the leucocytosis.