Differential expression and in vivo secretion of the antimicrobial peptides psoriasin (S100A7), RNase 7, human beta‐defensin‐2 and ‐3 in healthy human skin

Antimicrobial peptides (AMP) are key players in the skin's defense system. Previous observations suggest a site‐ and age‐dependent expression of individual AMP. We investigated the expression and secretion patterns of four important AMP in a representative collective of healthy human skin samples. Levels of psoriasin, RNase 7 and hBD‐3 expression – assessed by immunohistochemistry – varied between different body localisations. Older individuals expressed hBD‐2 more frequently. No gender‐related expression was observed. The in vivo secretion of psoriasin, measured in skin washing fluids using ELISA, was related to body localisation and age, whereas RNase 7 secretion showed no significant differences regarding these variables. HBD‐2 and ‐3 secretion could not be detected. Our findings suggest the usage of control samples matching localisation and approximate age (in the case of hBD‐2) for comparative immunohistochemical analysis. To avoid bias through great interindividual differences, sufficient large collectives should be used for in vivo secretion analyses.