Influence of sex, age, pubertal maturation and body mass index on circulating white blood cell counts in healthy European adolescents—the HELENA study

Percentiles 10th, 25th, 50th, 75th and 90th are presented for circulating white blood cells (WBC), neutrophils, lymphocytes, monocytes, eosinophils and basophils in healthy European adolescents (12.5–17.5 years, n = 405, 48.9 % boys), considering age, sex, puberty and body mass index (BMI). CD3 + (mature T cells), CD4 + (T helper), CD8 + (T cytotoxic), CD16 + 56 + (natural killer), CD19 + (B cells), CD3 + CD45RA + , CD4 + CD45RA + , CD8 + CD45RA + (naïve), CD3 + CD45RO + , CD4 + CD45RO + and CD8 + CD45RO + (memory) lymphocytes were also analysed by immunophenotyping. Girls presented higher WBC, neutrophil, CD3 + CD45RO + and CD4 + CD45RO + cell counts and CD3 + /CD19 + ratio, and lower CD3 + CD45RA + and CD4 + CD45RA + counts than boys. Age was associated with higher neutrophil counts and CD3 + /CD19 + , and lower CD19 + counts; in boys, with lower CD3 + CD45RA + , CD4 + CD45RA + and CD8 + CD45RA + counts as well; in girls, with higher WBC, CD3 + CD45RO + and CD4 + CD45RO + counts. Pubertal maturation in boys was associated with lower WBC and lymphocyte counts; in girls, with higher basophil, CD3 + CD45RO + and CD4 + CD45RO + values. BMI was associated with higher WBC counts; in boys, also with higher lymphocyte counts; in girls, with higher neutrophil, CD4 + , CD3 + CD45RO + and CD4 + CD45RO + counts. Conclusion : Our study provides normative values for circulating immune cells in adolescents, highlighting the importance of considering sex, age, pubertal maturation and BMI when establishing reference ranges for WBC in paediatric populations. What is known: • Reference values for white blood cell counts and immunophenotyping of lymphocyte subsets can constitute useful clinical tools and health indicators in both adult and paediatric populations. • Immune cell counts vary between childhood and adulthood . What is new: • Age and female sex were associated with higher WBC, neutrophil and T memory cell values . • Pubertal maturation was associated,with lower WBC and lymphocytes in boys and higher T memory cell counts in girls, while BMI was associated with higher WBC, mainly due to greater lymphocyte counts in boys, and to neutrophil and T memory cell counts in girls .