Demonstration of leukotriene B4 in the scale extracts of psoriasis and inflammatory pustular dermatoses. Correlation with leukocyte chemotactic activity and C5a anaphylatoxin.

We carried out quantification of the levels of leukotriene B4 (LTB4), a highly potent cell membrane-derived leukocyte chemotactic factor, in scale extracts of psoriasis and related inflammatory dermatoses characterized by sterile subcorneal pustule formation by using radioimmunoassay. A small amount of LTB4 was demonstrable even in extracts from non-inflammatory stratum corneum, but larger amounts were detected in the scale extract from pustular psoriasis and in those from psoriasis vulgaris. There was a significant correlation between the LTB4 and C5a levels in scale extracts, suggesting that complement activation and generation of LTB4 are a closely related event in psoriatic lesions. However, in contrast to highly significant correlation noted between the amount of C5a and chemotactic activity for polymorphonuclear leukocytes (PMN) detectable in scale extracts, LTB4 levels correlated only marginally with the chemotactic activity.