Expression of high-affinity IgE receptor on human peripheral blood dendritic cells in children.

Background: In a mouse model of viral induced atopic disease, expression of FcεRI on dendritic cells is critical. While adult human conventional (cDC) and plasmacytoid (pDC) dendritic cells have been shown to express FcεRI, it is not known if this receptor is expressed in childhood and how its expression is governed by IgE.

Methods: Following informed consent of subjects (n = 27, aged 12-188 months), peripheral blood was stained for surface expression of CD19, ILT7, CD1c, IgE, FcεRI and analyzed by flow cytometry (cDC: CD19(-) ILT7(-) CD1c(+); pDC: CD19(-) ILT7(+) CD1c(-)). Total and specific serum IgE levels to food and inhalant allergens were determined by ImmunoCAP, and the relationship between FcεRI expression on dendritic cells and sensitization, free IgE, cell bound IgE, and age was determined.

Results: Independent of sensitization status, FcεRI expression was noted on cDC and pDC as early as 12 months of age. Serum IgE level correlated with expression of FcεRI on cDC, but not pDC. Based on the concentration of IgE, a complex relationship was found between surface bound IgE and expression of FcεRI on cDC. pDC exhibited a linear relationship of FcεRI expression and bound IgE that was consistent through all IgE concentrations.

Conclusions: In children, FcεRI expression on cDC and pDC is modulated differently by serum and cell bound IgE. IgE governance of FcεRI expression on cDC depends upon a complex relationship. Further studies are needed to determine the functional roles of FcεRI on cDC and pDC.