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

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.