Halo 194 (Jan 2018)
Application of new parameters of platelets (CD61 and reticulated platelets) in laboratory monitoring trombocytopenia
Abstract
INTRODUCTION. Reticulated platelets are the youngest form of circulating platelets characterized by a residual amount of iRNA. It has been suggested that the reticulated platelet count, providing an estimate of thrombopoiesis. The platelet receptor CD61 is a receptor for fibrinogen, fibronectin, prothrombin, thrombospondin, vitronectin and von Willebrand factor. Flow-cytometric immunological determination of platelets number is proposed by the International Council for Standardization in Hematology (ICSH) as reference. The method is developed using monoclonal antibodies against platelets membrane antigens. The antibody directed against platelet receptor CD61 is the most used. OBJECTIVE. To determine significance of reticular platelets and platelet receptor CD61 testing in laboratorical diagnosis of platelets diseases. MATERIALS AND METHODS. A group of patients with thrombocytopenia in the Clinical Center of Serbia is examined. The experimental group 1 consisted of 28 patients (12 men and 16 women) with chronic thrombocytopenia, which are divided into two subgroups: with hypoplastic thrombocytopenia (12 patients) and destructive thrombocytopenia with hyperactive platelet lineage (16 patients). The experimental group 2 consisted of 30 patients (18 men, 12 women) with acute thrombocytopenia with platelets less than 50 x 109 /l, which are divided into two subgroups: with hypoplastic thrombocytopenia (18 patients) and destructive thrombocytopenia with hyperactive platelet lineage (12 patients). The control group consisted of 20 volunteers (9 men and 11 women), in which the platelet parameters (the number and medium platelets volume - MPV) were within the normal limits and therefore they did not take any treatment. The blood samples are collected in aliquots of 3 ml by venipuncture in Becton Dickinson's vacuum tubes with K-2 EDTA anticoagulant. The number of platelets (determined by the optical method-platelet count in the in the platelet counting chamber) and medium platelets' volume - MPV and the percentage of reticular platelets - rP% (is determined by flow-cytometric method) which are examined by hematological parameters. In the second part of the test, platelets' counting using monoclonal antibodies is directed to platelet receptor CD61 analyzer 'Cell Dyn Sapphire' (Abbott Diagnostics, USA) is added. RESULTS. There was a statistically significant difference between the percentage of reticular platelets between the control group and the patients with thrombocytopenia (13,31% against 1,78%). There was also a statistically significant difference against between reticular platelets from the patients with destructive thrombocytopenia (18,78%) and hypoplastic thrombocytopenia (6,02%). There was no statistically significant difference (p = 0.9431) between the number and and medium platelet volume (MPV) between levels of platelets and platelet receptor CD61, which is determined by PLTo method. The platelets values are determined by specific PLTi method which is statisticaly higher than the PLTo value (p = 0.0071) and platelet receptor CD61 values (p = 0.0049). CONCLUSION. Differential diagnostic methods are limited and the biopsy of bone marrow is considered as the 'gold standard' for diagnosis of thrombocytopenia. 'Flow'- cytometric analysis of reticulted platelets are additional, non-invasive diagnostic method. The task of biochemical laboratory is to encourage this type of test, in order to obtain more complete information of the diagnosis, treatment and thrombocytopenia' prognosis.
