The Possible Role of Vasoactive Substances for the Hemodynamic Effects of Rapidly Injected Antilymphocyte Globulin

Abstract

A rapid intravenous injection of ALG into splenectomized dogs induced an almost complete elimination of lymphocytes and an extensive but partly reversible thrombocytopenia during which platelets were trapped in the lung. During this trapping there was a significant decrease in arterial blood pressure, pulmonary blood volume and cardiac output concomitant with a marked increase in the portal pressure. The pulmonary arterial pressure remained unchanged. The hemodynamic effects are probably caused by a release of vasoactive substances which induced a decreased venous return from splanchnic pooling and stasis. Prostaglandins and histamine seem to play a dominant role, since Aspirin, promethazine and 48/80 markedly reduced the side-effects.

Role of Platelets and Lymphocytes for the Hemodynamic Effects of Rapidly Injected Antilymphocyte Globulin

“…This reaction does, however, not occur or is markedly reduced if these substances are injected into animals made thrombocytopenic [5,16,19,29] or into animals pre-treated with a sero tonin antagonist [28], indicating that the platelets play a central role in these circulatory reactions. In the present study, as well as in a previous study [11], it was found that the thrombocytopenia induced by ALG was also accompanied by a rise in the portal pressure, suggesting that the cir culatory changes were due to splanchnic pooling and liver stasis. In the present study, it was found that not only the ventilatory changes but also the changes in splanchnic circulation induced by ALG were abolished if the dogs were made thrombocytopenic.…”

“…In a previous study, it was suggested that a release of prostaglandins and histamine played a dominant role for the circulatory responses to ALG, as indicated by the protection given by pretreatment with Aspirin, antihistamine or 48/80 [11]. The present study indicates that platelets as well as lymphocytes must be present to trigger such a release.…”

“…Rapid intravenous injection of xenogenic antithymocyte globulin (ATG) in pigs [25] and injection of ALG in rats [6] or dogs [11] induced an anaphylactoid response. This response may be triggered by the specific immune reaction between ATG and the lymphocytes [25].…”