Several approaches have recently been carried out to attempt to establish a mouse transplantation model of psoriasis. To study the effects of superantigen-driven peripheral blood mononuclear cells (PBMCs) on the persistence of psoriasiform epidermis and cytokine gene expression of the grafted psoriatic skin, staphylococcal enterotoxin B (SEB)-stimulated PBMCs (SEB-PBMCs) from psoriatic patients were subcutaneously injected once or repeatedly under the grafted full-thickness involved psoriatic skin onto severe combined immunodeficient (SCID) mice. After 5 weeks, the persistence of a psoriasiform epidermis was most distinct in mice with repeated injection of SEB-PBMCs. E-selectin expression was observed on endothelial cells in the upper dermis in mice with repeated injection of both SEB-stimulated and unstimulated PBMCs, while mice with single injection of unstimulated or SEB-PBMCs did not show positive staining. Both interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma) mRNA were detected after 5 weeks, only in mice with repeated injection of SEB-PBMCs. It is concluded that continuous supply of the activated PBMCs may help the persistence of psoriasiform architecture more clearly, and that this transplantation mouse model may serve as an in vivo model for the study of the pathogenesis and therapy of psoriasis.