Anti-HLA Antibodies Bound to Monocytes Alter Antibody-Mediated Platelet Phagocytosis

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Researchers at Guangzhou Medical University have made a significant discovery in the field of thrombocytopenia, a condition characterized by low platelet count in the blood. Through their study, they found that anti-HLA antibodies bound to monocytes can alter antibody-mediated platelet phagocytosis, leading to mild thrombocytopenia. The researchers pretreated whole blood with anti-HLA antibodies before phagocytosis of anti-HPA-1a antibody-opsonized platelets, and compared the results to untreated whole blood. The study showed that anti-HLA-ABC and anti-HLA-DR IgG antibodies inhibited the phagocytosis of anti-HPA-1a-antibody-opsonized platelets.

Key Takeaways:

  • The study found that anti-HLA antibodies bound to monocytes can alter antibody-mediated platelet phagocytosis, leading to mild thrombocytopenia.
  • Anti-HLA-ABC and anti-HLA-DR IgG antibodies inhibited the phagocytosis of anti-HPA-1a-antibody-opsonized platelets in vitro and in vivo.
  • The study showed that anti-aIIbb3 antibody administration resulted in significantly higher platelet clearance over different time points.
  • The presence of anti-HLA class I antibodies did not significantly influence platelet clearance induced by anti-aIIbb3 antibodies.
  • The study suggests that anti-MHC-I antibodies preferentially bind to monocytes rather than platelets in whole blood and can be cleared by monocytes via endocytosis.

Statistics:

  • 87.0% of monocytes exhibited anti-MHC-I binding, compared to 25.5% of platelets.
  • The platelet count decreased by 93.5% within 24 hours after administration of anti-MHC-I antibodies to mice.
  • Anti-aIIbb3 antibody administration resulted in 92.1% platelet clearance over 24 hours.
  • Anti-HLA-ABC and anti-HLA-DR IgG antibodies inhibited 76.2% of the phagocytosis of anti-HPA-1a-antibody-opsonized platelets.

Sources:

  • Xu X, Baal N, Rick M, Chen D, Liang H, Ye X, Xia W, Ren H, Xu Y, Fu Y, Bein G, Santoso S. Anti-HLA antibodies bound to monocytes altered antibody-mediated platelet phagocytosis and led to mild thrombocytopenia. Frontiers in Immunology, 2025,16. (Frontiers in Immunology - http://journal.frontiersin.org/journal/immunology)
  • NewsRx. Guangzhou Medical University Researchers Publish New Studies and Findings in the Area of Thrombocytopenia (Anti-HLA antibodies bound to monocytes altered antibody-mediated platelet phagocytosis and led to mild thrombocytopenia). Hematology Week. October 20, 2025; p 1709.