Elevated plasma levels of specific antiplatelet glycoprotein autoantibodies in patients with primary Sjögren syndrome with thrombocytopenia.

INTRODUCTION: Thrombocytopenia is one of the primary Sjögren's syndrome (pSS) hematological manifestations. The objective of this study was to evaluate the possible roles of antiplatelet glycoprotein autoantibodies in the pathogenesis of thrombocytopenia in primary Sjögren's syndrome (pSS).

METHODS: The level of plasma anti-glycoprotein Ib, IIIa and IIb/IIIa autoantibodies in 36 pSS patients without thrombocytopenia and 35 pSS patients with thrombocytopenia, 36 Idiopathic thrombocytopenic purpura (ITP) patients and 39 normal control were measured with enzyme-linked immunosorbent assay (ELISA).

RESULTS: The level of anti-GPIb, GPIIIa, GPIIb/IIIa autoantibodies (A490) in the pSS with thrombocytopenia was significantly higher than that of pSS without thrombocytopenia (0.813 ± 0.161 vs 0.688 ± 0.133; 0.917 ± 0.094 vs 0.802 ± 0.070; 0.911 ± 0.125 vs 0.782 ± 0.109). Incidences of the anti-GPIb, GPIIIa, GPIIb/IIIa autoantibodies in the pSS with thrombocytopenia was significantly higher than that of pSS without thrombocytopenia (25.7% vs 0%; 65.7% vs 11.1%; 31.4% vs 0%). In patients with pSS, there was a lower platelet count in anti-GPIb, GPIIIa, GPIIb/IIIa autoantibodies positive patients ((25.67 ± 5.5) × 10^9/L vs (116.8 ± 84.52) × 10^9/L; 29.04 ± 11.33 × 10^9/L vs (152.0 ± 75.47) × 10^9/L; (31.55 ± 14.0) × 10^9/L vs (118.8 ± 85.24) × 10^9/L).

CONCLUSION: Elevated plasma levels of anti-platelet glycoprotein autoantibodies may play a role in the pathogenesis of thrombocytopenia in pSS. Key Points • The level of anti-GPIb, GPIIIa, GPIIb/IIIa autoantibodies (A490) in the pSS with thrombocytopenia was increased. • Incidences of the anti-GPIb, GPIIIa, GPIIb/IIIa autoantibodies in the pSS with thrombocytopenia was increased. • In patients with pSS, there was a lower platelet count in anti-GPIb, GPIIIa, GPIIb/IIIa autoantibodies positive patients.