Volumen: 3 # Number : 3
Publication Date : Noviembre - Diciembre Year: 1999
Authors: Graciela S. Cerrato, Alicia I. Rovó, Dolores P. Puente, Gonzalo Pombo, Ricardo R. Forastiero, Marta E. Martinuzzo.
Abstract: Idiopathic thrombocytopenic purpura (ITP) is an autoinmune disorded caused by platelet-specific autoantibodies that bind to target antigens on membrane of autologous platelets, leading to a rapid clearance by the reticuloendothelial system. Purpose: to evalute the efficacy as diagnostic method of PAICA (Platelet Asociated IgG (Characterization Assay), and its correlation with PAIgG (Platelet Associated IgG) in ITP patients. Patients and Methods: a total of 37 consecutive ITP patients (28 females and 9 males) were diagnosed on the basis of thrombositopenia and bone marrow examination, wich showed normal or increased number of megacariocytes. The mean age was 42.4 years (range 15-89). They were examyned by PAIgG (Leporrier M et al, Br J Haematol 1979) detecting only the total IgG associated to the surface of platelets, and PAICA, a new method for detecting autoantibodies boun to specific membrane glycoproteins in total platelets lysates (Laurent Macchi et al, Throm Haemost 1996). We have used murine monoclonal antibodies directed against two of the major glycoproteins of the platelets: GPllb-lla and lb-IX. Results: 13 of 37 patients showed negative results for PAIgG and PAICA. Twenty were positive for PAICA and 15 of them were also PAIgG positive. The specificity of these antibodies were found in 4 patients. There was a small group of 4 patients who were only posityve for PAIgG. Conclusions: diagnosis of ITP requires laboratory test capable of detecting platelet-reactive antibodies. PAIgG test allows only to identify total IgG boun to the surface of platelets, and in some cases it reflects the thrombocytopenia of non-inmune origin. PAICA is a more useful test to confirm the autoinmune etiology, and takes into account the surface bound and internal pools of antibodies in platelets. This suggest that identifying the antigen to wich antibodies are directed would probide an important advantage in the diagnosis of ITP. Nevertheless, none of these test is sensitive enough to detect the presence of antiplatelets antibodies in all patients samples.
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Pages : 270-276
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