Modulation of CD3-dependent lymphocyte proliferation by extracellular matrix proteins in atopic dermatitis.

Patients with atopic dermatitis were found to have an about 7-fold increased spontaneous proliferative response of peripheral blood lymphocytes and an about 4-fold elevation of CD3-dependent lymphocyte transformation as compared to normal controls. The CD3-dependent lymphocyte response in patients with severe atopic dermatitis lesions was increased to a lower degree than in those with mild skin lesions. Despite a highly increased CD3-dependent lymphocyte response, the extracellular matrix proteins could induce further co-stimulation of lymphocytes in patients with atopic dermatitis, similar to that in normal controls. However, co-activation by type IV collagen was markedly increased in patients with severe lesions, whereas co-stimulations by both type I collagen and fibronectin were decreased in patients with mild lesions. This finding reflects presumably the changes in lymphocyte subpopulations and their activities related to the recirculation of these cells through the active skin lesions and to the contact of T cells with extracellular matrix proteins. The percentage of CD26-positive lymphocytes was also significantly (p < 0.05) increased in patients with severe atopic dermatitis. These data indicate that helper T cells are excessively activated in atopic dermatitis and that the function of beta-1-integrin receptors underlying the extracellular matrix protein-mediated co-activation of CD3-dependent lymphocyte responses is modified by disease severity.