EXTREMELY LOW-LEVELS OF EPIDERMAL SKIN-DERIVED ANTILEUCOPROTEINASE ELAFIN IN A PATIENT WITH IMPETIGO HERPETIFORMIS/

Impetigo herpetiformis (IH) is a rare pustular dermatosis with unknown aetiology, typically occurring during pregnancy. Based upon a similar clinical and histological presentation, i.e. spongiform accumulation of polymorphonuclear leucocytes in the stratum corneum, several author s consider IH as a variant of generalized pustular psoriasis (GPP), wh ile others state that IH is a separate entity, Skin-derived antileucop roteinase (SKALP) is a strong and specific inhibitor of human leucocyt e elastase (HLE) and proteinase 3, two neutral proteinases that have b een implicated in leucocyte migration and tissue destruction, Previous ly we reported decreased SKALP activity in pustular forms of psoriasis compared with plaque psoriasis. In this study we present a case study of a patient with IH, where SKALP activity was measured using biochem ical and immunochemical techniques, Epidermal scales and sera were col lected during the course of the disease, Comparison was made with thre e patients with GPP and six patients with plaque psoriasis, Initially, anti-HLE activity in epidermal scales of the patient with IH was comp arable with values in patients with GPP, i.e. decreased compared with plaque psoriasis. During the course of the disease, anti-elastase acti vity dropped to undetectable levels, concomitant with the appearance o f free elastase activity, This finding suggests a total saturation of epidermal anti-HLE activity, Low levels of SKALP, presumably complexed with HLE, could be measured immunochemically in scale extracts. Serum levels of total SKALP correlated with tile disease activity, We sugge st that a reduced amount of epidermal SKALP contributes to an imbalanc e between elastase and its inhibitor, resulting in the formation of ep idermal pustules. This mechanism of pustule formation could apply both to GPP and IH, suggesting a final common pathway in the pathogenic me chanisms of IH and GPP.