Evaluation of Platelet count by the CELL-DYN Sapphire CD61 Immunoplatelet Method in Patients with Hematologic Diseases Receiving Chemotherapy

ABSTRACT

BACKGROUND: The automated hematologic analyzer has increased the precision and accuracy for platelet counting. However, spurious elevations of automated platelet counts occur occasionally in patients receiving chemotherapy or radiotherapy for solid organ tumors, leukemia, and other lymphomas. The CELL-DYN Sapphire analyzer (Abbott, USA) detects platelets with a CD61 monoclonal antibody and uses both impedance and optical technologies; thus, it is expected to present more accurate platelet counts. METHODS: We evaluated platelet counts obtained with the CELL-DYN Sapphire impedance, optical, and CD61 methods and compared them with the results obtained with the XE-2100 analyzer (Sysmex, Japan). We analyzed 111 samples from hospitalized patients with various hematologic diseases, who were receiving chemotherapy or radiotherapy. RESULTS: The results from the impedance, optical, and CD61 methods of CELL-DYN Sapphire and those from XE-2100 showed significant linearity, with correlation coefficients greater than 0.99. Three cases had significantly different platelet counts among the different methods used. Microscopic examination of these three cases showed very low platelet counts that corresponded with the low counts from the CD61 methods. It should be noted that because the automated blood counter assesses cell populations by their dimensions, many cellular fragments that were of the same size or smaller than platelets were thus counted as platelets. CONCLUSIONS: The CELL-DYN Sapphire analyzer has good precision, linearity and performance, comparable with the XE-2100 analyzer. As the CD61 methods of CELL-DYN Sapphire is specific for platelet, this method may reduce the interference from other blood components and count the exact platelet numbers.