CELLULAR INTERACTIONS AND ADHESION MOLECULES IN PSORIATIC SKIN

T-cell activation probably plays the most important role in hyperproli feration of keratinocytes in psoriasis. We present here our results co ncerning the interacting immunocompetent cells and their phenotypic an d functional characteristics in relation to psoriasis pathology. Immun ohistochemical analysis of skin biopsies from psoriasis patients, did indeed show that hyperproliferation of keratinocytes is associated wit h 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 th at psoriatic skin in general is in an activated state. This interpreta tion is further supported by the observation that the expression of se veral AR and other relevant activation markers when compared with thos e in nonlesional skin from contact dermatitis are increased in a signi ficant manner in the non-lesional skin of psoriasis patients. We have then followed up our investigations by generating T-cell lines from le sional psoriatic skin and studied their adhesion patterns on cultured endothelial cells in order to get better insight into the migration pa ttern 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 delt a (V delta 1(-)) T-cells can easily be generated from psoriatic patien ts. In a comparative kinetic study using unstimulated and stimulated c ultured human umbilical vein endothelial cells, we observed that TCR-g amma delta T cells showed different adhesion properties from that of T CR-alpha beta(+) T cell subsets. The overall results suggest that furt her studies on the cellular interactions (particularly concerning the expression and characteristics of the various adhesion receptors on di fferent skin cells) together with the elaborate functional characteris tics of T cells from psoriatic patients would help to elucidate the pa thomechanism of psoriasis.