RETICULOCYTES AND RETICULATED PLATELETS - SIMULTANEOUS MEASUREMENT INWHOLE-BLOOD BY FLOW-CYTOMETRY

Reticulated platelets are a fraction of newly released circulating ele ments characterized by a residual amount of RNA. It has been suggested that the reticulated platelet count, providing an estimate of thrombo poiesis in the same way as erythrocyte reticulocyte count is a measure of erythropoiesis, may be useful in the study of thrombocytopenic dis orders. Reticulated red cells and platelets can be analyzed by flow cy tometry using specific stains for nucleic acids such as Thiazole Orang e and Auramine-O. The aim of our work was to perform the simultaneous evaluation of reticulated elements in whole blood using a standard flo w cytometer and to correlate the results obtained with a dedicated cyt ometer. A group of 14 patients with abnormal absolute reticulocyte cou nts (range 1.1-11%) and a group of 41 patients showing a platelet disc rimination error when analyzed with a dedicated flow cytometer (Sysmex R1000) were enrolled. Linear amplification of both scatter and fluore scence was used to perform reticulocyte count. A gate was set on plate let dimensions, and logarithmic amplification of scatter and fluoresce nce was used to count reticulated platelets. A good correlation was ob tained both for results of reticulocyte count (r(2)=0.9825) and for re ticulated platelets (r(2)=0.8717) between our method and those using d edicated instruments. These data show that reticulated platelet count may be easily introduced in clinical laboratories that routinely perfo rm reticulocyte count by flow cytometry.