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

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.