A leukotactic factor in the stratum corneum of pustulosis palmaris et plantaris: a possible mechanism for the formation of intra-epidermal sterile pustules.

Previous studies on the chemotactic properties of soluble substances from psoriatic scales demonstrated the presence of complement-derived chemotactic factors (anaphylatoxins) that seem to play a crucial role in the production of typical psoriasiform tissue changes. The crude extract from the stratum corneum of lesions of pustulosis palmaris et plantaris (PPP) was also noted to contain highly chemotactic components for polymorphonuclear leukocytes (PMN's) as compared with a crude callus extract in the present study. The leukotactic factors contained in the major chemotactic fractions isolated by Sephadex G-75 chromatography revealed in vitro characteristics and in vivo biological activities very similar to those of the leukotactic factor derived from psoriasis scale reported in earlier work, i.e. complement cleavage products (C3a and C5a). On the basis of these findings we have reason to believe that pustule formation in PPP occurs through a mechanism that has a strong resemblance to that in pustular psoriasis. We hypothesize further that similar mechanism may be operative in other dermatoses in which the formation of sterile subcorneal pustules is a characteristic feature.