Age‐Matched Dendritic Cell Subpopulations Reference Values in Childhood

Dendritic cells (DCs) are the most potent antigen‐presenting cells and are the key link between the innate and adaptive immune response. Only a few reports with study populations of up to 50 individuals have been published with age‐based reference values for DC subpopulations in healthy children. Therefore, we aimed to establish reference ranges in a larger study population of 100 healthy children, which allowed age‐matched subgroups. Most previous studies were performed using a dual‐platform approach. In this study, a single‐platform approach in a lyse no‐wash procedure was used. DC subpopulations were defined as follows: CD45⁺CD85k⁺HLA‐DR⁺CD14^?CD16^?CD33⁺ cells as myeloid DCs (mDCs) and CD45⁺CD85k⁺HLA‐DR⁺CD14^?CD16^?CD123⁺ cells as plasmacytoid DCs (pDCs). Reference ranges were established using a semi‐parametric regression of age‐matched absolute and relative DC counts. We found a significant decline with increasing age in the medians of mDCs (P = 0.0003) and pDCs per μl peripheral blood (PB) (P = 0.004) and in the 50%, 90% and 95% reference ranges. We also identified significantly lower absolute cell counts of mDCs per μl PB in girls than in boys for all age groups (P = 0.0015). Due to the larger paediatric study population and single‐platform approach, this study may give a more precise overview of the normal age‐matched development of DC subpopulations and may provide a basis for analyzing abnormal DC counts in different illnesses or therapies such as post stem cell transplantation.