Prevalence of anti-beta(2) glycoprotein-I antibody in patients with primary or secondary immune thrombocytopenia

We determined the prevalence of antibodies to beta(2) glycoprotein-I (beta( 2)GPI) in sera of 57 patients with primary or secondary immune thrombocytop enia positive for platelet antibody (PAIgG) and in 16 healthy control subje cts. Both isotypes (IgG and IgM) of anti-beta(2)GPI were detected by means of semiquantitative ELISA and platelet antibodies were measured by means of flow cytometry using FITC-labeled anti-human Igc. Six (10.5 %) of 57 patie nts with immune thrombocytopenia had anti-beta(2)GPI, whereas none of the 1 6 healthy subjects had anti-beta(2)GPI, Four were positive for IgM anti-bet a(2)GPI, one for Ige anti-beta(2)GPI, and one was positive both for IgM and IgG anti-beta(2)GPI, There was no significant association between the pres ence of anti-beta(2)GPI and the severity of thrombocytopenia. Our findings suggest that some patients with immune thrombocytopenia have anti-beta(2)GP I in addition to the increased PAIgG; however, the results do not support a major role for anti-beta(2)GPI in the pathogenesis of immune thrombocytope nia.