Plasma Protein Requirements for Human Platelet Aggregation

Abstract

Summary 1. Three cationic proteins–fibrinogen, Hageman factor, and gamma globulin‐are all capable of restoring aggregation capability of washed human platelets. 2. The aggregation‐restoring effect of gamma globulin is inhibited by acetic proteins in subfractions of Cohn fraction IV and fractions V and VI. 3. Artificial enhancement of the net negative charge of plasma proteins through acylation produces derivatives capable of inhibiting platelet aggregation in platelet‐rich plasma. 4. It is proposed that the rate of platelet aggregation is regulated in part by the equilibrium between cationic and anionic proteins in plasma and on the platelet membrane surface. This concept finds support in the following clinical observations. 5. Platelets of Glanzmann's thrombasthenia incapable of aggregation fail to adsorb cationic proteins to their surface. 6. Purified myeloma proteins from patients with platelet dysfunction do not restore aggregation of normal washed platelets and inhibit the aggregation‐restoring effect of normal IgG. 7. Enhanced platelet aggregation demonstrable in chronic, active glomerular disease may result from the loss in the urine of plasma proteins normally inhibiting platelet aggregation.

The Effect of Trypsin and Storage on Aggregation and Release of Human Gel-Filtered Platelets

“…The need for fibrinogen is in accord with observations of Bang et al (2) and of Levy-Toledano etal. (15).…”

Pneumococcus-induced serotonin release from human platelets. Identification of the participating plasma/serum factor as immunoglobulin.

“…The method of preparing washed platelets was modified from methods described previously (10,11). Venous blood (45 ml) was taken into 5 ml of acid citrate dextrose (ACD formula A) in 50-ml conical plastic culture tubes.…”

Isolation of plasma co‐factor in adenosine diphosphate‐induced aggregation of bovine platelets

“…Studies on plasma proteins participating in ADP-induced aggregation of platelets have been done by several workers; Born and Cross [l] reported a heat labile protein from pig plasma which may be present in euglobulin fraction and in a preparation of blood coagulation factor VIII, and Deykin et al found two plasma proteins in human blood, fibrinogen and a heat stable protein [2]. Bang et al [3] reported that fibrinogen, Hageman factor and gamma globulin in human blood are capable of restoring aggregation capability of washed human platelets. Ardlie et al [4] demonstrated that ADP-induced aggregation of washed platelets from rabbit blood occurs in modified Tyrode's solution containing bovine serum albumin.…”