Anti-allergic drug olopatadine suppresses murine contact hypersensitivity and downmodulates antigen-presenting ability of epidermal Langerhans cells

Olopatadine hydrochloride is an H1-receptor-blocker but has other anti-allergic pharmacological potencies. We investigated whether olopatadine inhibits murine contact hypersensitivity, focussing on its modulatory action on epidermal Langerhans cells serving as antigen-presenting cells. While BALB/c mice were sensitized and challenged epicutaneously with hapten, they were administered intraperitoneally with olopatadine. Olopatadine at 1 or 0.2 mg/kg of weight significantly suppressed the sensitivity when injected at least once before sensitization or challenge. In olopatadine-injected mice, the ability of Langerhans cells to present hapten to primed T cells was reduced with decreased expression of MHC class II and co-stimulatory molecules. Langerhans cells exposed in vitro to 10−5 or 10−6 M olopatadine had less antigen-presenting activity than control, whereas neither T cell proliferation nor keratinocyte production of IL-1α and IP-10 was affected at these doses. These findings suggest that olopatadine downmodulates contact hypersensitivity at least partly by interfering with the antigen-presenting ability of Langerhans cells.