Establishment of the reference intervals of lymphocyte subsets for healthy Chinese Han adults and its influencing factors

Background: Cellular immune monitoring is becoming more critical in the clinic, but its application has not yet become sufficiently widespread. One reason may be the different reference intervals among clinical laboratories due to several factors. Percentage and number of lymphocyte subsets are standard indicators of cellular immune detection. The present study aimed to establish standardized reference intervals of lymphocyte subsets in the healthy Chinese Han adult population and examine such influencing factors as age, gender, region, and measurement instruments. Methods: A total of 496 healthy Chinese Han people aged 18-59 years from 3 China Mainland regions (north, east, and south) were enrolled. The sample of each center was simultaneously examined by three flow cytometers (FACSCantoTMII, FACSLyricTM, and FACSCaliburTM). A single-platform flow cytometrybased absolute count technique was used to quantify the percentage and number of each lymphocyte subset. The flow cytometry results were analyzed by variance analysis and Z test to determine the influence of age, gender, and instruments on lymphocyte subsets. Results: Multi-center, age-specific, and gender-specific reference intervals of healthy Chinese Han adults' lymphocyte subsets were established. There was no statistical difference in the results from the three flow cytometers. Gender affected the results of CD4+ (%) and the absolute count of CD3-CD16+CD56+, where CD4+ (%) was higher in women, and the absolute count of CD3-CD16+CD56+ was higher in men. Age mainly affected the CD4+/CD8+ ratio, which was statistically higher in groups aged over 40 years; the percentage and number of CD3-CD19+ were more elevated in age groups below 30 years; however, the difference was not statistically significant. Conclusions: This study established the reference intervals of lymphocyte subsets for healthy Chinese Han adult populations under the standardized methods. This study was the first nationwide study in China to use a flow cytometry-based single-platform method to establish the reference intervals of lymphocyte subsets of the healthy Chinese Han adult population. Gender and age were shown to influence the results of lymphocyte subsets.