EXCESSIVE COSTIMULATION OF CD3-DEPENDENT LYMPHOCYTE-RESPONSE BY EXTRACELLULAR-MATRIX PROTEINS IN SEVERE WIDESPREAD PSORIASIS

Costimulation of anti-CD3-triggered proliferative T-cell responses by type I and type IV collagen and fibronectin was studied in 25 patients with psoriasis and 12 healthy subjects. The stimulation index of anti -CD3-mediated responses in the presence of type I collagen was about h alf that in the controls. Although the CD3-dependent proliferative res ponse of psoriatic lymphocytes in patients with active widespread plaq ue psoriasis was reduced by about 50%, costimulatory responses induced by type IV collagen and fibronectin were found to be enhanced in rela tion to the controls. The degree of costimulation by type IV collagen and fibronectin was related to disease severity. The highest values of the stimulation index were found in patients with a PASI greater than 24, skin involvement of more than 40% of body surface area, and a dur ation of psoriatic lesions of more than 3 months. The results indicate d that in active widespread plaque psoriasis subpopulations of T cells bearing receptors for some extracellular matrix proteins were increas ed in the peripheral blood. A factor responsible for this phenomenon m ay be trafficking of T cells through the basement membrane zone of pso riatic lesions, which presumably causes modification of T cell immunol ogical responsiveness after recirculation.