EFFECT OF ANTI-P1 A-1 ANTIBODY ON HUMAN-PLATELETS .1. ROLE OF COMPLEMENT

  • 1 January 1979
    • journal article
    • research article
    • Vol. 53  (4) , 567-577
Abstract
The interaction of complement with human platelets was studied. Complement was activated by Ig[immunoglobulin]G anti-P1A1 antibody obtained from 3 patients with the post-transfusion purpura syndrome. A heparin-plasma buffer system was used that permits complement activation and also preserves platelet function. With this system complement activation was efficient, and platelet immune alteration was extensive. Anti-P1A1 antibody was effective only in the presence of complement, in which case platelet lysis and serotonin release (release reaction) in the absence of lysis were observed. Platelet lysis, as assessed by 51Cr loss, required 10-fold more antibody than was necessary to induce platelet aggregation and release of 14C-serotonin. This platelet release reaction required an intact classic complement sequence through C6 [6th complement component]. The extent of platelet serotonin release paralleled the depletion of C1 and C4 from platelet-rich plasma. Concentrations of antibody insufficient to induce platelet aggregation and serotonin release could still activate C1 and deposit increased C3 on the platelet surface. Complement activation by anti-P1A1 antibody can alter human platelets in a nonlytic system. Several phases of complement-mediated human platelet alteration are possible, depending on the concentration of anti-P1A1 antibody.