Bullous pemphigoid blister fluid stimulates eosinophil colony formation and activates eosinophils

An eosinophil stimulating material (ESM) is described in the blister fluids (BF) of six patients with bullous pemphigoid (BP). This ESM is similar in function to a subspecies of human colony stimulating factor (CSF), CSF-alpha, since (i) it stimulated the production from bone marrow cells of day 14 colonies (31 +/- 15, arithmetic mean +/- 1 s.e.m. colonies, n = 5) in semi-solid agar, (ii) a large proportion (47 +/- 12%, n = 5) of these colonies were eosinophilic and (iii) it activated purified peripheral eosinophils as judged by increased autofluorescence (a mean increase of 23.6 +/- 6.6 units measured by flow cytometry, n = 10). BF from patients with four other blistering diseases, burn blisters, suction blisters from normal, eosinophilic or BP patients, various sera, histamine and eosinophil chemotactic factor (ECF-A) lacked activities in these assays. This description of a tissue accumulation of a CSF like substance suggests that there exists a physiological role for CSF in the periphery. In addition it supports the concept that local activation of eosinophils contributes to the pathogenesis of BP.