Interleukin 17 is a T cell‐derived cytokine that induces the release of pro‐inflammatory mediators in a wide range of cell types. Recently, a subset of IL‐17‐producing T helper cells (Th17) distinct from Th1 and Th2 cells has been described, which constitutes a new T cell polarization state. Aberrant Th17 responses and overexpression of IL‐17 have been implicated in a number of autoimmune disorders including rheumatoid arthritis and multiple sclerosis. Molecules blocking IL‐17 such as IL‐17‐specific monoclonal antibodies have proved to be effective in ameliorating disease in animal models. Hitherto, active immunization targeting IL‐17 is an untried approach. Herein we explore the potential of neutralizing IL‐17 by active immunization using virus‐like particles conjugated with recombinant IL‐17 (IL‐17‐VLP). Immunization with IL‐17‐VLP induced high levels of anti‐IL‐17 antibodies thereby overcoming natural tolerance, even in the absence of added adjuvant. Mice immunized with IL‐17‐VLP had lower incidence of disease, slower progression to disease and reduced scores of disease severity in both collagen‐induced arthritis and experimental autoimmune encephalomyelitis. Active immunization against IL‐17 therefore represents a novel therapeutic approach for the treatment of chronic inflammatory diseases.

See accompanying commentary at http://dx.doi.org/10.1002/eji.200636760