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.