Role of platelets and lymphocytes for the hemodynamic effects of rapidly injected antilymphocyte globulin.

Xenogenic antilymphocyte globulin (ALG) given as a rapid intravenous injection into dogs caused a significant decrease in arterial blood pressure and oxygenation as well as an increase in portal pressure. At the same time, there was an almost complete elimination of lymphocytes and an extensive but almost completely reversible thrombocytopenia. Lymphocytopenia induced by a previous injection of ALG was found to eliminate completely the circulatory response to a second injection of ALG in spite of the fact that an extensive thrombocytopenia was induced. Extensive thrombocytopenia induced by injection of an antiplatelet globulin was also found to prevent completely the hemodynamic effects of ALG although as many lymphocytes were eliminated as in the intact dogs. Thus both platelets and lymphocytes are necessary to trigger the circulatory response induced by ALG.