Numerical, phenotypic and functional differences in human dermal resident memory T cells between reticular dermal layers

Abstract

Background: Resident memory T (T_RM) cells and immunosuppressive Foxp3-expressing regulatory T_RM (regT_RM) cells are present in healthy, non-inflamed and inflamed human skin. Both types of cells are found in both the epidermis and dermis with the dermis being much thicker than the epidermis. However, it is unclear if T_RM and regT_RM cells differ between reticular dermal layers in terms of number, function or characteristics.

Methods: This study examined numerical, phenotypic and functional differences in T_RM and regT_RM cells between the upper and lower reticular dermis in healthy, non-inflamed human skin using flow cytometry.

Results: The phenotype and cytokine expressions of both types of cells were similar between reticular dermal layers. However, the cell count of both T_RM and regT_RM cells was significantly higher in the upper reticular dermis than in the lower reticular dermis.

Conclusions: T_RM and regT_RM cells are phenotypically and functionally identical between reticular dermal layers. However, both types of cells are more abundant in the upper reticular dermis.