Immunohistochemical stainings of a keratome biopsy before (A, B and C) transplantation and after (D, E and F) transplantation and treatment in the psoriasis xenograft SCID mouse. Before transplantation the expression of CD3 (A), CD4 (B) and CD8 (C) is seen in follicular structures and diffusely distributed in the skin. However, the intensity of CD4 expression is slightly decreased compared to freshly excised and fixed psoriatic skin (data not shown). Five weeks after transplantation including a three week treatment with vehicle the expression of CD3 (D) expression in the skin seems to be increased. In contrast, CD4 (E) and CD8 (F; arrows) expression is down regulated after vehicle treatment. The skin from A, B, C, D, E and F is from the same donor.