Topical application of F991, an immunoglobulin free light chain antagonist, prevents development of contact sensitivity in mice

Summary Background Exposure to reactive chemicals or environmental allergens can lead to hypersensitivity reactions in the skin of predisposed people. Most of these reactions are of atopic origin, but a subgroup of patients exhibits skin hypersensitivity reactions without features of atopy. Objective This study was undertaken to examine the effect of inhibiting the action of Ig‐free light chains in a murine model for non‐atopic skin hypersensitivity by dermal application of the free light chain antagonist F991. Methods To study the efficacy of F991, BALB/c mice were either passively immunized with trinitrophenyl (TNP)‐specific immunoglobulin light chains (IgLC) and challenged with the hapten picryl chloride (PCl) or actively skin‐sensitized and challenged with dinitrofluorobenzene (DNFB). The effect of F991 or control treatment was investigated by measuring local edema formation and the production of pro‐inflammatory cytokines. Results Passive immunization with TNP‐specific IgLC resulted in an increase in ear swelling 2 h after PCl challenge. F991 inhibited this enhanced ear swelling in a dose‐dependent manner when applied 4 h before the sensitization with IgLC. F991 also inhibited DNFB‐induced contact hypersensitivity reaction in the mouse skin 2 and 24 h after challenge when applied before challenge. Besides the prophylactic action, F991 when applied 2 h after DNFB‐challenge, it was also able to attenuate symptoms of the DNFB‐induced hypersensitivity reaction at 24 h after challenge. We showed that the beneficial effects of F991 are restricted to the side of application. Conclusion F991 is able to effectively alleviate symptoms of contact sensitivity in mice. Our study suggests that local interference with IgLC‐induced allergic symptoms may be attractive in the treatment of hypersensitivity responses.