Animal experiments by Hoa et al. (2024) demonstrated that Bifidobacterium longum KACC91563 alleviated allergic contact dermatitis in mice by downregulating serum levels of key pro-inflammatory and Th2/Th17 associated cytokines, including IgE, IL-4, IL-5, IL-13, IL-17, and TNF-α. Here, IL5 is linked to allergic contact dermatitis.