Recent unpublished work from our laboratory showed, that JAM-C expression of lymphocytes can be up-regulated through specific activators. Hence, we hypothesize, that JAM-C expression is elevated in patients with psoriasis. As it is currently not know, which factors may influence the expression of JAM-C, we intend to analyse JAM-C expression on CD3+CD41- cells at several time-points during the treatment of psoriatic patients. Expression of JAM-C will then be correlated to disease activity (PASI).