[Current status of CD34⁺cell enumeration assay in clinical laboratories and its improvement]

Objective: To investigate the current status and problems of CD34⁺ cell enumeration in clinical laboratories and provide suggestions for the development of quality improvement programs. Methods: A total of 101 laboratories participating in the national external quality assessment program of CD34⁺cell enumeration were surveyed. Questionnaires and quality assessment materials were distributed to collect information on assay methodology and testing results. Quality control requirements for CD34⁺cell enumeration were determined according to the international guidelines, and the compliance of the surveyed laboratories was analyzed. Testing results were analyzed in groups and compared with the College of American Pathologists (CAP) quality assessment data. Results: A total of 97 laboratories returned the questionnaires and 99 laboratories returned the results of quality assessment materials. The questionnaire data showed high compliance rates of quality control requirements such as gating protocols, pipetting methods, and the number of cells acquired (92.8%, 83.9%, and 82.5% respectively). However, these laboratories had relatively low compliance rates such as the use of whole blood quality control materials for internal quality control, selection of erythrocyte lysing reagents, sample processing method, whether to report absolute count results, and quality control of equipment (5.2 %, 28.9%, 39.2%, 46.4%, and 55.7%, respectively). Testing results demonstrated that the coefficient of variation (CV) of percent counts was similar to the CAP quality assessment data, but the CV of absolute counts was greater than the CAP quality assessment data. Conclusions: Clinical laboratories have poor compliance with some quality control requirements and the variability of absolute count results between different laboratories is not satisfactory. Therefore, it is recommended that clinical laboratories should strengthen the training related to the quality control of CD34⁺cell enumeration, especially the absolute counting.