title: Specific interaction of HLA antibodies (eluates) with washed platelets.
abstract: The mechanism of complement-independent action of HLA-A2 antibodies (eluates) on washed platelets was investigated. HLA-specific alteration was confirmed by serological (platelet micro-complement fixation), morphological (platelet spreading) and functional parameters (platelet aggregation, inhibition of collagen-induced platelet aggregation, [14C]serotonin release). In the presence of fibrinogen and calcium ions, HLA antibodies induced instantaneous platelet aggregation and release. Although no morphological (spreading) and functional changes (collagen-induded aggregation) were seen, these platelets did not aggregate or release when fibrinogen was subsequently added. When platelets--in the presence of fibrinogen--were incubated with antibody concentrations too low to induce platelet aggregation or release, specific reduction of platelet reactivity was observed by subsequent collagen aggregation. HLA-specific action of antibodies on washed platelets was inhibited by apyrase and acetyl-salicylic acid, indicating an active participation of platelets in HLA antibody-induced platelet alteration.
mesh_terms: D000906:Antibodies; D001792:Blood Platelets / Q000276:immunology* / Q000648:ultrastructure; D002118:Calcium / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology; D003165:Complement System Proteins; D005340:Fibrinogen / Q000494:pharmacology; D006680:HLA Antigens; D006649:Histocompatibility Antigens; D006801:Humans; D010974:Platelet Aggregation; D012701:Serotonin / Q000378:metabolism
chemical_list: D000906:Antibodies; D006680:HLA Antigens; D006649:Histocompatibility Antigens; D012701:Serotonin; D005340:Fibrinogen; D003094:Collagen; D003165:Complement System Proteins; D002118:Calcium