Objective To detect the changes and clinical significance of the expression of anti‐GPⅡb/Ⅲa and anti‐GPⅠb/ⅠX on anti‐secreting B cells in patient with thrombocytopenia .Methods Expression of anti‐GPⅡb/Ⅲa and anti‐GPⅠb/ⅠX specific autoantibodies in thrombocytopenia were tested with (CBA) .Results There were significantly more circulating anti‐GPⅠ b/ⅠX and anti‐GPⅡb/Ⅲa antibody‐producing B cells in primary ITP(P<0 .05) for all comparisons .For diagnosing primary ITP ,the an‐ti‐GPⅠb/ⅠX had 43% sensitivity and 89% specificity ,whereas the anti‐GPⅡ b/Ⅲ a had 86% sensitivity and 83% specificity . When two tests were combined ,the sensitivity improved to 90% without a reduction in specificity .Conclusion The assay for detec‐ting anti‐GPⅠb/ⅠX is useful for identifying patients with ITP ,but its utility for diagnosing ITP is inferior to the anti‐GPⅡb/Ⅲa assay .