Significance Of Specific Autoantibodies Against Platelet Glycoprotein And Lymphocyte Subpopulations In Idiopathic Thrombocytopenic Purpura

Objective To evaluate the clinical significance of specific autoantibodies against platelet glycoprotein and lymphocyte subpopulations in idiopathic thrombocytopenic purpura .Methods part 1: Specific autoantibodies against platelet glycoprotein were measured by a monoclonal antibody immobilization of platelet antigen assay (MAIPA). part 2: The ratios of lymphocyte subpopulations (CD3+,CD3+CD4+,CD3+CD8+,CD19+, CD19+CD5+) in peripheral blood were analyzed by flow cytometry (FCM). Results part 1: We found that 75% (30/40) and 65% (26/40) patients had specific antibodies to GPIIbIIIa and GPIbα. 25% (10/40) of patients had mono-specific antibodies to GPIIbIIIa and 15% (6/40) had mono-specific antibodies to GPIbα. Another 50% of the patients (20/40) had antibodies to both antigens and 10% (4/40) of patients had no detectable antibody to either platelet antigen. There was a significant inverse correlation between the positive possibility of autoantibody against GPIIbIIIa and platelet counts (b=-0.071, P<0.01), and similar results were observed in autoantibody against GPIbα(b=-0.092, P<0.01). After treatments, we found that the frequency of refractory cases in patients with antibodies to both antigens (8/20) was significantly higher than that in patients with mono-specific antibodies (1/16) (χ2=6.09,P<0.05) in ITP. part 2: Compared with the ratios of lymphocyte subpopulations in healthy controls, CD3+, CD3+CD4+ subsets and CD3+CD4+/ CD3+CD8+ in ITP patients(36) significantly decreased and CD3+CD8+, CD19+ and CD19+CD5+ subsets obviously increased(P<0.05). After treatments, the effective cases in ITP patients were twenty-seven and the refractory cases were nine. CD3+, CD3+CD4+ subsets and CD3+CD4+/CD3+CD8+ in effective cases increased but CD3+CD8+, CD19+, CD19+CD5+ subsets decreased compared with that of the ITP patients before treatments(P<0.05). At the same time, the ratios of lymphocyte subpopulations after treatments in refractory cases did not obviously changed (P>0.05).Conclusions 1. Severity and the frequency of refractory cases in ITP patients were related with specific autoantibodies against platelet glycoprotein. 2. We suggest that the specific autoantibodies against platelet glycoprotein and the changes of lymphocyte subpopulations in idiopathic thrombocytopenic purpura might play a significant role in the pathogenesis and therapeutics of patients with ITP.