RESUMEN
OBJECTIVE: To study the distribution of peripheral blood lymphocyte subsets in healthy children aged 0-6 years. METHODS: A total of 826 healthy Han children aged 0-6 years were recruited. According to their age, the children were divided into four groups: newborn, infant, toddler and preschool. Their peripheral blood samples were collected to measure the percentages of lymphocyte subsets by flow cytometry. RESULTS: There were significant differences in the percentages of CD3+ T cells, CD3+CD4+ T cells and CD3-CD19+ B cells and the CD4+/CD8+ ratio between boys and girls (P<0.05). The girls had a lower percentage of CD3-CD19+ B cells, higher percentages of CD3+ T cells and CD3+CD4+ T cells and a higher CD4+/CD8+ ratio than the boys. The newborn group had the highest percentages of CD3+ T cells and CD3+CD4+ T cells and the highest CD4+/CD8+ ratio (P<0.05). The percentage of CD3+CD4+ T cells and the CD4+/CD8+ ratio gradually decreased with age and the preschool group had the lowest values (P<0.05). The newborn group had the lowest percentages of CD3-CD19+ B cells and CD3-CD16+CD56+ NK cells (P<0.05). The percentage of CD3-CD16+CD56+ NK cells gradually increased with age and the preschool group had the highest percentage (P<0.05). The percentage of CD3-CD19+ B cells reached the peak in the toddler period and then decreased with age (P<0.05). The preschool group had the highest percentage of CD3+CD8+ T cells (P<0.05). The variation trend of distribution of lymphocyte subsets in boys from different age groups was consistent with that in children from different age groups. For girls, the newborn group had the highest percentage of CD3+CD4+ T cells and CD4+/CD8+ ratio (P<0.05). CONCLUSIONS: The distribution of peripheral blood lymphocyte subsets in healthy children is significantly different across ages and sexes. Therefore, the reference values should be established according to age and sex.