RESUMO
<p><b>OBJECTIVE</b>To investigate the influence of divalent cation chelator EDTA and heparin sodium on the detection of ITP platelet-specific autoantibodies by the modified monoclonal antibody immobilization of platelet antigen assay (MAIPA) and to explore the relationship between types of platelet specific autoantibodies and glucocorticoid efficacy.</p><p><b>METHODS</b>The samples were obtained from EDTA- and heparin- anticoagulant ITP patients, respectively, so as to detect the platelet-specific autoantibodies (GPIIb/IIIa and GPIbα) in 140 ITP samples by modified MAIPA, then the differences between these two methods were compared.</p><p><b>RESULTS</b>Out of 140 cases in EDTA group, 55 cases were positive for GPIIb/IIIa, while 76 cases in heparin group were positive for GPIIb/IIIa, 42 cases in both group were repeatable; among them 13 cases were positive in EDTA group and negative in heparin group, while 34 cases were positive in heparin group and negative in EDTA group, there was significant difference between them (x (2) = 9.38, P < 0.05), 62 cases in 140 cases of EDTA group were positive for GPIba, while 51 cases in heparin group were positive for GPIba, 42 cases in both group were repeatabe; among them 20 cases were positive in EDTA group and negative in heparin group, while 9 cases were positive in heparin group and negative in EDTA group, there was no significant difference between them (x (2) = 3.44, P > 0.05). A total of 320 cases received a standard glucocorticoid treatment, out of them 143 cases were positive for GPIbα with effective rate 39.9%, 177 cases were negative for GPIbα with effective rate 79.7%, there was statisticalty significant difference between them (x (2) = 53.115, P < 0.05).</p><p><b>CONCLUSION</b>EDTA anticoagulant (a divalent cation chelator) has a significant influence on detection of ITP platelet-specific autoantibodies (GPIIb/IIIa) by a modified MAIPA method and the GPIbα antibody positive may be one of the important factors that results in un-sensitivity of ITP patients to glucocorticoid treatment.</p>
