Age‐related changes in lymphocyte subpopulations in healthy Thai children

BACKGROUND: Ethnicity and environmental factors can influence the percentages of lymphocyte subpopulations. This study aimed to assess the percentages of lymphocyte subpopulations according to age in Thai children. METHODS: This was a cross‐sectional study. The percentages of lymphocyte subpopulations were measured in umbilical cord blood and peripheral blood of healthy Thai children aged 1 month‐15 years. The participants were stratified into five age groups: (a) cord blood; (b) age < 2 years; (c) age 2‐5 years; (d) age 5‐10 years; and (e) age 10‐15 years. RESULTS: Of 182 total samples, 32, 39, 41, 28, and 42 were from cord blood, children aged <2 years, children aged 2‐5 years, children aged 5‐10 years, and children aged 10‐15 years, respectively. The percentages of most lymphocyte subpopulations including CD8 + T cells, CD19 + cells, γδ T cells, double‐negative T cells, NK cells, and NK T cells increased significantly with age. Only the CD4+ T‐cell percentage decreased in older children. Moderate correlations were observed between age and the percentages of CD4+ T cells, γδ T cells, NK cells, NK T cells, and double‐negative T cells. Weak correlations were observed between age and the percentages of CD8+ T cells and CD19+ cells. CONCLUSION: Our study demonstrated age‐related changes in the percentages of lymphocyte subpopulations in Thai children, which differed from those described in other countries. Therefore, the establishment of age‐specific reference values for lymphocyte subsets in each country is recommended.