Galectin-1 Expression in CD8 T Lymphocytes Controls Inflammation in Contact Hypersensitivity.

Allergic contact dermatitis, also known as contact hypersensitivity, is a frequent T-cell‒mediated inflammatory skin disease characterized by red, itchy, swollen, and cracked skin. It is caused by the direct contact with an allergen and/or irritant hapten. Galectin-1 (Gal-1) is a β-galactoside‒binding lectin, which is highly expressed in several types of immune cells. The role of endogenous Gal-1 in contact hypersensitivity is not known. We found that Gal-1‒deficient mice display more sustained and prolonged skin inflammation than wild-type mice after oxazolone treatment. Gal-1‒deficient mice have increased CD8 T cells and neutrophilic infiltration in the skin. After the sensitization phase, Gal-1‒depleted mice showed an increased frequency of central memory CD8 T cells and IFN-γ secretion by CD8 T cells. The absence of Gal-1 does not affect the migration of transferred CD4 and CD8 T cells from the blood to the lymph nodes or to the skin. The depletion of CD4 T lymphocytes as well as adoptive transfer experiments demonstrated that endogenous expression of Gal-1 on CD8 T lymphocytes exerts a major role in the control of contact hypersensitivity model. These data underscore the protective role of endogenous Gal-1 in CD8 but not CD4 T cells in the development of allergic contact dermatitis.