Anti-α_vβ₃ Antibodies in Chronic Immune Thrombocytopenic Purpura

Summary

In chronic immune thrombocytopenic purpura (ITP), anti-GPIIb-IIIa (α_IIbβ₃) autoantibodies have been detected in serum and/or platelet-associated IgG (PAIgG) and considered as one of the major causes. We examined whether anti-α_vβ₃ antibodies might be present in ITP cases because of the similarity between α_vβ₃ and GPIIb-IIIa (α_IIbβ₃). Modified antigen capture ELISA (MACE) using human umbilical vein endothelial cells (HUVEC) showed the presence of serum anti-α_vβ₃ antibodies in 23 of 80 ITP patients (29%). Cross-adsorption studies between platelets and HUVEC demonstrated that most of anti-α_vβ₃ and anti-GPIIb-IIIa antibodies exclusively reacted with α_vβ₃ and GPIIb-IIIa, respectively. Platelet-associated anti-GPIIb-IIIa antibodies did not react with α_vβ₃, either. Interestingly, patients having anti-α_vβ₃ antibodies showed significantly lower platelet counts than negative patients. These results indicate the serum anti-α_vβ₃ antibodies are different ones from the classical anti-GPIIb-IIIa (α_IIbβ₃) antibodies and would provide a new insight into the pathophysiology of ITP as well as the autoantigenic epitopes on β₃ integrins.

Keywords

ITP - autoantibody - β₃ integrin - GPIIb-IIIa - α_vβ₃

• References

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