Abstract: Objective To establish the reference ranges of peripheral blood lymphocyte subpopulations values in Gansu children of preschool age.Methods Gansu Han children who received a preoperative, postoperative or routine physical examination aged from 0 to 7 years old were enrolled into the study. The children, who have cardio-cerebral vascular disease, abnormal blood routine, liver and kidney dysfunction, infection within 3 weeks of lymphocyte subpopulation detection, primary immunodeficiency disease, were excluded. Included children were divided into neonatal group (0 to 28 d), infant group (28 d to 12 months), toddler age group (1 to 3 years) and preschool age group (3 to 7 years). Peripheral blood was collected, and relative counts of lymphocyte subpopulations were detected by flow four, color cytometric analysis within 24 h. The (P_2.5, P_97.5) was used as the normal reference range of each index.Results ①A total of 792 children were enrolled into the analysis of this article, including 472 boys, 320 girls, 174 newborns, 216 infants, 170 toddlers, and 232 preschoolers. ②The interior group comparison between males and females showed there was a statistically significant difference between males and females in CD4⁺T、CD8⁺T、B、NK lymphocyte percentages and CD4⁺/CD8⁺ value in the neonatal group; in CD4⁺T、CD8⁺T、B lymphocyte percentages and CD4⁺/CD8⁺ value in the infant group; in T、CD4⁺T、B、NK lymphocyte percentages in the preschool age group. ③The percentages of lymphocyte subpopulations were statistically significant in the distribution of girls and boys in all age groups. The T and CD4⁺T lymphocyte percentages declined with age, and the trend in decreasing degree was similar between boys and girls. The CD8⁺T lymphocyte percentage increased with age, and the trend of girls in increasing degree was more obvious. B lymphocyte percentage showed a marked rise in children within 1 year old (from neonatal group to infant group), followed by a gradual decline, and the trend of girls was more moderate. NK lymphocyte percentage, on the other hand, displayed a pattern of change almost opposite that for B lymphocyte,which decreased within 1 year and then increased, and the trend of boys was more obvious.Conclusion The distribution of lymphocyte subpopulations percentages in healthy children is related to region, age and gender.

Key words: Children, Flowcytometry, Lymphocyte subpopulations, Preschool age, Reference range