The Antiheparin And Antiplatelet-Aggregating Effects Of Human α₁-Acid Glycoprotein; Influence On Heparin Tolerance In Acute Phase Reactions

The antiheparin effect of human α₁-n-acid glycoprotein (α₁-acid GP), in thrmbin clotting time systems, was originally observed after the addition of purified α₁-acid GP to heparinized, citrated human plasma. The α₁-acid GP used in that and other studies was rather crude. In the present study, however, a similar antiheparin effect has been observed with highly purified, non-desialyzed α₁-n-acid GP. Furthermore, the inhibitory effect of this highly purified α₁-acid GP on the thronbin-induced platelet aggregation was identical to that of the less purified preparation. The antiheparin effect of highly purified α₁-acid GP isolated in parallel frcm pooled plasma of patients with acute phase reactions and from healthy controls was likewise identical.

In patients (n=10), with acute phase reaction, only the concentration of α₁-acid GP was negatively correlated with the heparin thrcrnbin clotting time (r=0.42), indicating α₁-acid GP to be a major contributor to the increased heparin tolerance observed during such disease states.

Removal of α₁-acid GP by precipitating with rabbit anti- human α₁-acid GP antibodies failed to danonstrate the heparin-neutralizing effect of α₁-acid GP, probably because inmunoglobulins per se possess heparin-neutralizing activity.

Our findings suggest that α₁-acid GP, during the acute phase reaction, interacts in a way to reduce untimely consequences of plasma hypercoagulability and/or platelet reactivity.