The effect of ageing on phenotype and function of monocyte-derived Langerhans cells

Background With increasing age the immune system shows functional decline. In the skin this is associated with an increased incidence of epidermal malignancies and infections. Epidermal Langerhans cells (LCs) act as sentinels of the immune system, recognizing, processing and presenting antigen and inducing T-cell responses. Previous investigations have demonstrated a reduction in the number of epidermal LCs in elderly subjects. Moreover, the ability of LCs to migrate in response to tumour necrosis factor (TNF)-alpha, but not interleukin (IL)-1 beta, is significantly impaired in the elderly. Objectives To characterize further the changes in LC function that are associated with increasing chronological age, we have evaluated age-related changes in the response of monocyte-derived LCs (mLCs) to IL-1 beta and TNF-alpha. Methods The phenotype and function of mLCs were compared in six young (<= 30 years) and six aged (>= 70 years) healthy individuals using a combination of flow cytometry, cytokine and chemokine array, and a Transwell migration assay. Results Monocytes from aged individuals were able to differentiate into LCs. There were no significant differences in expression of activation markers, or in baseline or inducible cytokine secretion, by mLCs derived from aged or young subjects. Furthermore, migration in response to a chemokine ligand, CCL19, was equivalent in both age groups. Conclusions These data demonstrate that changes in LC function in the elderly are not associated with changes in systemic dendritic cell phenotype and function. Conditioning of LCs in situ by the epidermal microenvironment is likely to be more important.