Release of β lysin from platelets caused by antigen antibody complexes, purified enzymes, and platelet aggregating substances

Abstract

The release of β-lysin, which followed the intravenous injection of antigen-antibody complexes, did not take place when these complexes were added to citrated whole blood but did occur in heparinized blood. β-Lysin release in heparinized blood was inhibited by citrate but was reversed by the addition of calcium ions that implicated complement reactions. Fourteen different enzymes were added to platelet-rich plasma (PRP). Streptokinase, neuraminidase, papain, phospholipase C, sulfatase, and trypsin caused platelets to release significant quantities of β-lysin, whereas elastase, phosphatase, protease, ribonuclease A, hyaluronidase, lipase, and pepsin caused little or no increase in the plasma β-lysin concentration. One enzyme, fibrinolysin, inactivated β-lysin faster than it was released. The enzyme-induced release of β-lysin from PRP was often accompanied by a reduction in the number of platelets. The intravenous injection of streptokinase, neuraminidase, and sulfatase caused in vivo releases of β-lysin into the plasma. The platelet-aggregating substances collagen, arachidonic acid, and adenosine 5'-diphosphate caused β-lysin to be released from PRP. The platelet-aggregating substances L-epinephrine, zymosan, fibrinogen, reserpine, and serotonin caused little or no release of β-lysin from platelets. The results of this study indicate that the release of β-lysin during antigen-antibody-complement reactions, blood coagulation, phagocytosis, and inflammation could be enzyme mediated.