Disturbed platelet aggregation to collagen associated with an antibody against an 85- to 90-Kd platelet glycoprotein in a patient with prolonged bleeding time.

摘要: We studied a 5-year-old girl presenting with markedly prolonged bleeding time. Her platelets were refractory to collagen stimulation, but the response other agonists was normal. There no coagulation abnormalities as measured by standard tests. Two-dimensional electrophoresis showed of patient's platelet membrane glycoproteins. When plasma or purified IgG mixed normal platelets, collagen-induced aggregation blocked. Western blotting presence an antibody in directed against protein molecular weight 85 90 Kd under both UMEROUS MEMBRANE proteins have been proN posed receptor on blood platelets. Most evidence so far has obtained favor integrin complex glycoprotein (GP) Ia/IIa. Human that do not express surface GPIa adhere aggregate collagen.'" The GPIa/IIa complex, specific adsorption fibers Mg2',4,5 and incorporated into phosphatidylcholine liposomes, supports adhesion these liposomes collagen! Both GPIa/IIa-bearing liposome can be inhibited murine monoclonal anti-GPIa antib~dy.~.~ Furthermore, we recently described patient whose unresponsive collagen, agonists. This phenomenon associated autoantibody GPIa." GPVI implicated following description deficiency failed react collagen." also did human isolated from another defective plateletcollagen interaction.'* Recently, strong GPIV act receptor." Rabbit antibodies inhibit interaction collagen; competes membrane-bound activation induced binds fibrils. report here studies collagen. her plasma, which 85-