Interleukin-8-positive neutrophils in psoriasis

We performed an immunohistochemical study to try to determine the cellular source of interleukin-8 (IL-8) in psoriatic skin lesions. IL-8 was positive ly stained in the vast majority of neutrophils but not in the mononuclear c ells, macrophages, or keratinocytes. IL-8-positive neutrophils were seen bo th in Munro's microabcesses in cases of psoriasis vulgaris and in a small s pongiform pustule and much larger macropustules of Kogoj in cases of pustul ar psoriasis. Some IL-8-positive neutrophils were observed in the upper der mis of pustular psoriasis. The staining was considered to be specific becau se it could be completely blocked by preabsorption with recombinant IL-8. I n addition, stimulation of human neutrophils with lipopolysaccharide (LPS) or tumor necrosis factor-alpha. (TNF-alpha) for 18 h induced IL-8 productio n in vitro. In our study, IL-8 was expressed in the neutrophils of psoriasi s, suggesting that neutrophils are one of the sources of IL-8 in psoriasis. The expression of IL-8 and the influx of neutrophils led us to speculate t hat the IL-8 autocrine and/or paracrine system functions in the formation o f the microabcesses and pustules in proriasis. (C) 2001 Elsevier Science Ir eland Ltd. All rights reserved.