Platelet Auto-antibodies

In conditions associated with thrombocytopenia, platelet destruction may be mediated by auto-antibodies directed against platelet surface antigens. Although various methods such as radioimmunoassay and enzyme-based assays can detect platelet-associated IgG, flow cytometry provides a rapid, sensitive, and accurate method that requires only a small sample volume.

To detect immunoglobulins bound to platelet surfaces, platelets isolated from plasma are incubated with fluorescein (FITC)-conjugated anti-IgG, anti-IgM, or anti-IgA antibodies. After washing, samples are analyzed by flow cytometry to determine the percentage of immunoglobulin-positive platelets. Flow cytometry offers several advantages, including simplicity, high reproducibility, and the ability to analyze as few as 5,000 platelets per assay—particularly useful in cases of severe thrombocytopenia.

Patients with idiopathic thrombocytopenic purpura (ITP) may demonstrate platelet auto-antibodies, while patients with infections, sepsis associated with malignancy, acute leukemia, or drug-induced thrombocytopenia may not.

• Send at room temperature
• Do not refrigerate
• Deliver to the laboratory within 24 hours

Flow Cytometry

Negative
Reported as negative or positive

• Lazarchick, J. and Hall, S.  Platelet-associated IgG assay using flow cytometric analysis.  J. Immunol.  Meth. 87:275, 1986.

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