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Comparison of the direct platelet immunofluorescence test (direct PIFT) with a modified direct monoclonal antibody‐specific immobilization of platelet antigens (direct MAIPA) in detection of platelet‐associated IgG
Author(s) -
Joutsi Lotta,
Kekomäki Riitta
Publication year - 1997
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1046/j.1365-2141.1997.d01-1995.x
Subject(s) - platelet , direct fluorescent antibody , monoclonal antibody , immunofluorescence , medicine , antigen , immunology , antibody , indirect immunofluorescence
Glycoprotein (GP)‐specific platelet‐associated IgG (PA‐IgG) may be demonstrable in autoimmune‐mediated thrombocytopenia. We studied 159 consecutive patients with histories of thrombocytopenia by a modified direct monoclonal antibody‐specific immobilization of platelet antigens (direct MAIPA) assay, which immobilizes GP IIb/IIIa, GP Ib/IX and GP Ia/IIa simultaneously. This modification requires smaller quantities of platelets than standard measurements performed separately. PA‐IgG was present in 84/159 (53%) patients, as shown by the direct platelet immunofluorescence test (PIFT) with flow cytometry as a reference. PA‐IgG against GP IIb/IIIa and/or GP Ib/IX and/or GP Ia/IIa was noted in 46 patients (29%), of whom 93% (43/46) were also PA‐IgG positive. The amount of PA‐IgG detected by PIFT correlated directly with that detected by direct MAIPA ( r =0.71; P <0.0001). Only three patients 12548 with negative direct PIFT had GP‐specific PA‐IgG. GPV‐specific PA‐IgG was detected in 13 (10%) of the 125 patients, in whom further studies could be performed. In the subgroup of patients with GP‐specific PA‐IgG, the median fluorescence intensities of direct PIFT were higher than in patients with no GP‐specific PA‐IgG ( P <0.001). Direct PIFT and direct MAIPA divided the patients into asymmetric subgroups. However, the relative roles of these tests in the diagnosis of autoimmune‐mediated thrombocytopenia await further studies.