Effects of psoriatic scale extracts on oxidative metabolic responses in granulocytes assessed by chemiluminescence

Abstract

The peptide fractions containing C5a des arg and anionic neutrophil activating peptide (ANAP) and the low-molecular-weight fractions containing LTB4 in psoriatic scale extracts exert a potent polymorphonuclear leukocyte (PMN) chemotactic activity. To evaluate whether any of these components in the psoriatic scale extracts stimulate a respiratory burst in PMNs, we studied luminol-dependent chemiluminescence (CL) in PMNs under their direct stimulation. After fractionation by molecular sieve chromatography, pooled peptide fractions eluting near the cytochrome c marker from eight samples induced high CL in PMNs, whereas those eluted in low-molecular-weight fractions after vitamin B12 marker were very weak in this response. Moreover, in six samples such low-molecular-weight fractions eluting near the vitamin B12 marker were found to have a suppressive effect on the oxidative metabolism of neutrophils induced by other stimulators. These findings suggest that the fraction of chemotactic peptides in psoriatic scales plays a major role in the activation of PMNs, inducing tissue damage in the psoriatic lesional epidermis. On the other hand, at least some low-molecular-weight components in psoriatic scales seem to exert an inhibitory effect on the respiratory burst induced by other activators.