Flow cytometry for the diagnosis of autoimmune thrombocytopenia.

Autoimmune thrombocytopenia is a disorder characterized by antibody-mediated accelerated platelet destruction. Despite its clinical importance, the diagnosis of autoimmune thrombocytopenia is one of exclusion, thus inevitably associated with potential difficulties. Current clinically applicable methods used to determine antigen-specific antibodies, primarily directed to GPIIb/IIIa (CD41a) and GPIb (CD42b), include the monoclonal antibody-specific immobilization of platelet antigen (MAIPA) assay and the radioactive immunobead assay. Neither of these assays is commonly used by clinical laboratories, however, because of methodologic and practical limitations. As a result, diagnoses are generally based on clinical impression despite patient presentations that are sometimes complex. To overcome some of these difficulties, flow cytometric techniques have been developed, employing standard methods and equipment suitable for testing a single sample or multiple samples, as may occur in cases of autoimmune thrombocytopenia. The availability of a feasible technique such as flow cytometry, with improved sensitivity and specificity, should facilitate the routine use of a diagnostic method in the evaluation of thrombo-cytopenic patients suspected of having an autoimmune disorder and permit follow-up to determine immune remission.