Sera from patients with palmoplantar pustulosis show immunoreactivity against endothelial cells.

Palmoplantar pustulosis (PPP) is considered to be a variant of psoriasis, although recently it has been shown to be genetically different from psoriasis vulgaris (1). The majority of patients with PPP are women and smokers. The final target for inflammation in this condition is the palmoplantar sweat duct (2, 3), but the mechanisms underlying the inflammation are poorly characterized. PPP patients have co-morbidity, with an increased prevalence of autoimmune thyroid disease, coeliac disease (4), abnormal calcium homeostasis and a greatly increased risk for diabetes type 2 (5).The possibility that PPP might be an autoimmune disease has recently been suggested by us, as sera from 47% of PPP patients reacted with papil-lary endothelium in palmar skin from healthy subjects, as assessed by indirect immunofluorescence (IIF) (6). The main purpose of this study was to determine whether PPP sera also show immunoreactivity against non-palmar skin and non-dermal tissues. In addition, the immunoreactivity of PPP sera against cultured dermal endothelial cell and palmar skin proteins was studied using a Western blot technique. Sera were obtained from 43 women and 1 man with typical PPP on the palms and/or soles. Twenty-one of these 44 new sera (47.7%) induced IIF staining of the endothelium in the palmar skin from a healthy woman, which is in agreement with our first study (6). Sera from 18 PPP patients studied previously (6) were obtained 1–6 years after the first samples and were used for follow-up screening of the IIF pattern in palmar skin. With 16 of these 18 PPP sera the staining results were the same as in the first sample (7 were still negative, 9 still positive). The positive staining had the same pattern (chain-like) and intensity as before. Two sera previously giving weak IIF staining were now negative. There had been only mild changes in the clinical conditions in the majority of these patients. Two patients who had stopped smoking had unchanged , strong endothelial IIF, despite almost total clearance of the PPP lesions in one of them and marked improvement in the other. The IIF pattern induced by PPP sera in palmar skin thus persists over time regardless of variation in clinical activity. With the intention of screening for IIF in non-palmar skin and non-dermal tissues, sera from 10 PPP patients, 5 healthy non-smokers and 5 patients with eczema on the hands, were used. Five of the PPP sera had previously produced strong endothelial IIF …