Cytokines at different stratum corneum levels in normal and sodium lauryl sulphate-irritated skin

Background/purpose: Cytokines play an important role in inflammatory and repair processes occurring in the skin. The objectives of this study were to determine the amounts of cytokines and protein isolated by tape stripping in the different layers of the stratum corneum (SC), and to compare normal skin with skin exposed in vivo to the irritant sodium lauryl sulphate (SLS). Methods: In eight volunteers, we determined the amount of total and soluble protein and also interleukin-1 alpha (IL-1 alpha) in pooled tape strips obtained from the upper, intermediate and lower parts of the SC. Three different types of tape were compared (Diamond((R)), D-squame((R)) or Sentega((R)) tape). In a separate study, 20 volunteers were repeatedly exposed to 0.1% SLS over a 3-week period. The amounts of IL-1 alpha, IL-1RA and IL-8 in strips obtained from the three different SC levels of SLS-exposed skin were compared with an unexposed site. Results: For normal skin, the amounts of soluble protein and IL-1 alpha were similar for the three tapes. Diamond((R)) tape showed the highest yield of total protein. The total protein yield per strip decreased to lower SC levels, whereas soluble protein and IL-1 alpha normalized by soluble protein did not change across the SC. After SLS induced skin irritation, IL-1 alpha decreased and IL-1RA and IL-8 increased at increasing depth into the SC. Conclusion: Tape stripping is a suitable method to determine SC cytokine concentrations in human skin. With this technique, it is possible to study changes in cytokine concentrations at different SC layers after skin irritation.