Psoriasis is a visible manifestation of the skin's defense against micro-organisms

The recent discovery that human epidermal cells themselves make and secrete the components necessary for activation of the alternative complement pathway appears to provide an explanation for how human skin is ordinarily able to avoid colonization by molds and other organisms. It also helps clarify the mechanisms underlying clinical and laboratory findings seen in chronic mucocutaneous candidiasis, dandruff, and psoriasis. Psoriasis seems best explainable as a visible, late stage of the inflammatory sequelae of activation of the alternative complement pathway in the epidermis.