In Human Skin, UVB Initiates Early Induction of IL-10 Over IL-12 Preferentially in the Expanding Dermal Monocytic/Macrophagic Population

The study examined the effects of UVB radiation on immune responses in human skin, focusing on cytokine production by dermal monocytes/macrophages. It found that UVB exposure led to an early and significant increase in IL-10 production, while IL-12 production was downregulated. This shift towards an IL-10-dominant environment began as early as 6 hours post-exposure and peaked at 24-48 hours, contributing to an immunosuppressive state in the skin. The findings highlighted the role of IL-10 in modulating immune responses by maintaining low IL-12 levels and inhibiting cell-mediated immunity, suggesting a mechanism for limiting inflammatory injury in UV-exposed skin.