Evidence for a contributory role of a xenogeneic immune response in experimental epidermolysis bullosa acquisita

Autoimmune diseases affect a large fraction of the population in Western countries. To elucidate the underlying causes, autoantibody transfer-induced mouse models have been established that greatly contributed to the understanding of the pathophysiology of these diseases. However, the role of a potentially co-occurring murine xenogeneic immune response to commonly utilized rabbit anti-mouse IgG remains poorly understood. Using the established rabbit anti-mouse type VII collagen (COL7) IgG-induced mouse model of the mucocutaneous blistering disorder epidermolysis bullosa acquisita (EBA), we found in this study a profound T- and B-cell response along with an altered cytokine expression profile in draining lymph nodes of mice injected with the xenogeneic IgG. This was associated with the formation of circulating and skin-bound mouse anti-rabbit IgG in wild-type but not CD154-deficient or B-cell-deficient JHT mice challenged with pathogenic rabbit IgG. Development of EBA skin lesions was attenuated in the two mouse strains lacking a B-cell response at later observation time points, but was not affected in mice treated with the T-cell trafficking blocker FTY720. Collectively, our results implicate a host's xenoreactive immune response to rabbit anti-mouse COL7 IgG, a confounding effect that may contribute to immune complex-driven inflammation and tissue damage in this antibody transfer-induced EBA mouse model, especially at later time points. In this regard, it may be recommended to finish the evaluation of results obtained by experiments employing antibody-transferred mouse models within the first 2 weeks after the pathogenic antibody injection.