Significant age- and gender-related variability of main lymphocyte subsets in paediatric patients: Latvian data.

Age- and gender-related variability of main lymphocyte subsets (T, B and NK cell absolute counts and percentages from Ly; T4, T8 and DN cell absolute counts and percentages from lymphocytes and from T cells; T4:T8 and T:B ratios) was studied in a large cohort of paediatric patients (2 days-17 years) at yearly intervals. A total of 4128 six-color TBNK tests performed on BD FACSCanto II flow cytometer were assessed; patients with immune deficiencies and tumours were not included. The study revealed significant age- and gender-related changes in all subsets. Absolute counts of T, B, T4 cells dropped from neonates to adolescents, decrease in T8 and NK cells was milder; relative count of T cells increased with age and that of B cells decreased; T4:T8 ratio went down and T:B ratio grew. Total T, T4 cells and T4:T8 ratio were significantly higher in girls, while T8, NK and DN cells were significantly higher in boys; significantly higher relative and absolute B cell counts in boys appeared in adolescence. We compared our results with reference values for healthy children (Tosato et al, Cytometry A. 2015;87:81); there was a good concordance, except for DN cells. Advantages of using patient cohort instead of healthy children as reference, possibilities for adjusting age- and gender-specific reference ranges and potential international data pooling are discussed.