Rapid Isolation of Functional ex vivo Human Skin Tissue-Resident Memory T Lymphocytes

Studies in animal models have shown that skin tissue-resident memory T (T-RM) cells provide enhanced and immediate effector function at the site of infection. However, analyses of skin T-RM cells in humans have been hindered by the lack of an optimized isolation protocol. Here, we present a combinatorial strategy-the 6-h collagenase IV digestion and gentle tissue dissociation - for rapid and efficient isolation of skin T-RM cells with skin tissue-specific immune features. In comparison with paired blood circulating memory T cells, these ex vivo isolated skin T cells express typical T-RM cell markers and display higher polyfunctional properties. Moreover, these isolated cells can also be assessed for longer periods of time in ex vivo cultures. Thus, the optimized isolation protocol provides a valuable tool for further understanding of human skin T-RM cells, especially for direct comparison with peripheral blood T cells at the same sample collection time.