Antiplatelet antibodies in patients with ITP and patient with platelet refractoriness

Abstract

Background: Immune thrombocytopenic purpura is an acquired disorder, in which accelerated platelet consumption is due to PLT autoantibodies. The diagnosis of immune thrombocytopenic purpura is a diagnosis of exclusion. Nevertheless, the assessment of platelet antibodies has been reported as helpful for the diagnosis and the follow-up of ITP patients. Refractoriness to platelet transfusion is generally considered one of the major obstacles in treating thrombocytopenic patients with hematologic disorders. Refractoriness is mostly due to anti-HLA antibodies and rarely due to platelet specific antibodies. This study was meant to asses the role of flowcytometry in detection of antiplatelet antibodies in comparison to monoclonal antibodies Immbolization of platelet antigens (MAIPA). Methods: PAIgs were determined in 18 ITP patients and in 5 healthy controls in parallel. MAIPA testing was performed in all patients and controls. HLA antibodies (FPRA) were determined in 12 PTR patients and 5 matched control with no PTR. Results: FCM detect high level of PAIgs in acute ITP patients than those who develops chronic form and those in remission. MAIPA found platelet specific antibodies in 15/18 (83.3%) of ITP patients. In the platelet refractoriness FCM detect significant elevation of all HLA antibodies groups between platelet refractoriness patients as compared to control. The highest frequency was 33.3% for HLA group I, 41.7% for HLA group 2, HLA group 3 and 16.7% for HLA group 4 in PTR patients. However, the frequency of total PAIgs was 25% in patients with platelet refractoriness Conclusions: FCM is a useful tool in the diagnosis and follow-up of ITP patients so can be used as a screening method. Platelet glycoprotein antibody assay by MAIPA is a specific assay for the diagnosis of idiopathic thrombocytopenic purpura.

Keywords

• Platelets antibodies