Characterization of lesional psoriatic skin T lymphocyte clones.

T cells are considered to play a role in the pathomechanism of psoriasis. Therefore we investigated the cytokine production patterns of T cell clones that were randomly prepared from chronic plaque psoriasis lesions of 2 patients. 67% of the 49 T lymphocyte clones (TLC) expressed CD4 and 33% expressed CD8 (ratio 2:1), while gamma delta-TCR expression was absent. The production of IL-4, IFN-gamma, IL-2 and IL-6 was measured in supernatants of TLC following PHA plus PMA stimulation. Different groups of clones could be distinguished according to their IL-4/IFN-gamma production ratio. In addition to Th0 cells (low IL-4/low IFN-gamma), low IL-4/high IFN-gamma producers as well as high IL-4/low IFN-gamma producing clones were found, suggesting the presence of Th1- and Th2-like subsets. Upon stimulation, all TLC secreted low levels of IL-2 whereas a minority of the TLC secreted low levels of IL-6. These results may imply that T cells in psoriasis lesions do not show shifts towards either a Th1 or a Th2 cytokine production profile.