A study of local immunity in psoriasis.

We have studied biopsies of lesional skin with monoclonal and polyclonal antibodies to determine the nature of the infiltrate in different forms of psoriasis. In guttate psoriasis the number of Langerhans cells (LC) was not increased and CD8+ cells predominated, however, most CD4+ cells were activated. In erythrodermal psoriasis some CDI+ cells were found in the dermis although CD8+ cells predominated and were activated. In palmo-plantar psoriasis LC were found in the epidermis and superficial dermis and CD4+ cells were more numerous than CD8+ cells, some in turn expressing HLA-DR. In flexural psoriasis the LC formed clusters in the epidermis, and activated CD4+ cells predominated. In psoriasis vulgaris CD4+ cells predominated over CD8+ although the latter were activated. Our observations tend to support Valdimarsson's hypothesis on the immune basis of psoriasis, but we believe that two cycles coexist in psoriasis--one inflammatory and the other immunological--and that interaction between these leads to epidermal hyperproliferation.