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Intravenous immunoglobulins induce CD32-mediated platelet aggregation in vitro
A Pollreisz1, A Assinger, S Hacker
1Department of Surgery, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria.
The British Journal of Dermatology
|June 21, 2008
Summary
Intravenous immunoglobulins (IVIg) and cytomegalovirus immunoglobulins (CMVIg) can cause platelet aggregation by binding to CD32 receptors. This mechanism may explain thrombosis risk and suggests caution when using IVIg with platelets.
Area of Science:
- Immunology
- Hematology
- Pharmacology
Background:
- Intravenous immunoglobulins (IVIg) and cytomegalovirus immunoglobulins (CMVIg) are increasingly used in immunocompromised patients.
- A rare side effect is intravascular thrombosis, potentially linked to hyperviscosity.
- Previous research indicated rabbit antithymocyte globulin induces platelet aggregation via CD32.
Purpose of the Study:
- To determine if IVIg and CMVIg induce CD32-dependent platelet aggregation.
- Investigate the role of the Fc IgG receptor (CD32) in immunoglobulin-mediated platelet activation.
Main Methods:
- Platelet aggregation was measured using an aggregometer with CMVIg or IVIg.
- Platelet activation markers (CD62P) and soluble CD40L (sCD40L) were assessed via flow cytometry and ELISA.
- Experiments utilized therapeutic concentrations of immunoglobulins and a blocking antibody (AT10) against CD32.
Main Results:
- CMVIg and IVIg significantly induced platelet aggregation in vitro.
- Increased expression of CD62P and secretion of sCD40L were observed upon incubation with CMVIg and IVIg.
- The platelet aggregation induced by CMVIg and IVIg was completely blocked by the anti-CD32 antibody AT10.
Conclusions:
- CMVIg and IVIg activate platelets via CD32 binding, leading to aggregation.
- This Fc-dependent mechanism provides a potential explanation for in vivo thrombosis.
- Clinical caution is advised for concurrent use of packed platelets and IVIg in autoimmune conditions.
