Induction of psoriasiform inflammation by a bacterial superantigen in the SCID-hu xenogeneic transplantation model.

Psoriasis is a chronic skin disease affecting about 2% of the Caucasian population, characterized by co-existing inflammation and epidermal hyperproliferation. A T-lymphocyte-mediated autoimmune reaction induced by bacterial superantigens might be central in its pathogenesis. To model psoriasiform inflammation, we transplanted clinically uninvolved skin from psoriatic patients onto SCID mice. Repetitive intradermal injections with a bacterial superantigen and simultaneous intraperitoneal injections with the patients superantigen-stimulated peripheral mononuclear blood cells resulted in an inflammatory reaction exhibiting some of the hallmarks of psoriasis, e.g. epidermal hyperproliferation, papillomatosis, focal neo-expression of ICAMI, and an exocytotic T-lymphocytic infiltrate characterized by the expression of the cutaneous lymphocyte-associated antigen. These observations document the potential of superantigens to trigger psoriasiform dermatitis and provide a model to study lymphocyte homing.