CELLULAR INTERACTIONS AND ADHESION MOLECULES IN PSORIATIC SKIN

T-cell activation probably plays the most important role in hyperproliferation of keratinocytes in psoriasis. We present here our results concerning the interacting immunocompetent cells and their phenotypic and functional characteristics in relation to psoriasis pathology. Immunohistochemical analysis of skin biopsies from psoriasis patients, did indeed show that hyperproliferation of keratinocytes is associated with increased vasculature and increased influx of MHC class II molecules expressing immunocompetent cells. Furthermore, in psoriasis, several adhesion molecules and other relevant activation markers were found to be upregulated even in the non-lesional psoriatic skin, indicating that psoriatic skin in general is in an activated state. This interpretation is further supported by the observation that the expression of several AR and other relevant activation markers when compared with those in nonlesional skin from contact dermatitis are increased in a significant manner in the non-lesional skin of psoriasis patients. We have then followed up our investigations by generating T-cell lines from lesional psoriatic skin and studied their adhesion patterns on cultured endothelial cells in order to get better insight into the migration pattern of different T cell subsets in psoriasis pathology. Our results indicate that different T-cell subsets CD4(+), CD8(+) (both TCR-alpha beta(+)) CD4-/CD8(+) TCR-gamma delta(+) and CD4(-)CD8(-)TCR-gamma delta (V delta 1(-)) T-cells can easily be generated from psoriatic patients. In a comparative kinetic study using unstimulated and stimulated cultured human umbilical vein endothelial cells, we observed that TCR-gamma delta T cells showed different adhesion properties from that of TCR-alpha beta(+) T cell subsets. The overall results suggest that further studies on the cellular interactions (particularly concerning the expression and characteristics of the various adhesion receptors on different skin cells) together with the elaborate functional characteristics of T cells from psoriatic patients would help to elucidate the pathomechanism of psoriasis.