Characterization of skin-resident T cells using a crawl-out method and flow cytometry.

A large fraction of the skin-homing T-cell population resides in the skin even under resting, non-inflammatory conditions. Here, we used a crawl-out culture method to retrieve T cells from human skin and characterized them using flow cytometric analysis. On average, 48000 viable, non-proliferating cells were retrieved per biopsy. We found that human skin contains a larger fraction of IL-17-, IL-4-, IL-10- and IL-22-positive T cells as compared with paired blood samples. Our research indicates that it is feasible to use the crawl-out method in combination with flow cytometry to characterize T-cell subpopulations in patient-derived skin biopsies. This method enables further study of the skin immune system and could function as a valuable tool for evaluation of the effects of immunotherapy in skin diseases.