INTER-LABORATORY COMPARISON OF CD34⁺ CELL ENUMERATION

Abstract

Accurate enumeration of CD34⁺ cells is crucial for peripheral blood stem cell transplantation. However, there is currently no standardization or external quality control of CD34⁺ cell enumeration technics in Japan. To assess data variability among laboratories, we quantified CD34⁺ cells isolated from the same fresh peripheral blood stem cell samples at six expert laboratories on the same day that they were harvested from patients. The coefficient of variation was less than 25%, and data from all laboratories were closely correlated. However, data obtained from one laboratory were significantly lower than data from other laboratories. Inappropriate methods of erythrocyte lysis and cell washing-rather than non-ISHAGE gating or dual platform methods-may have caused these significantly lower counts. However, expected results were obtained when fixed control cells were enumerated. External quality assessment using appropriate samples and standardization of methodologies for CD34⁺ enumeration are important for reducing inter-laboratory variation in results.