Stimulus-dependent increased generation of oxygen intermediates in monocytes and polymorphonuclear leukocytes in psoriasis.

Based on recent findings indicating increased respiratory burst activity of monocytes (M phi) and polymorphonuclear leukocytes (PMN) in psoriasis upon stimulation with zymosan particles, we examined the question of whether incubation with various stimuli always results in augmented oxidative metabolism in psoriatic phagocytes. We compared M phi and PMN isolated from the peripheral blood of 12 patients with psoriasis and 12 control individuals. We measured the generation of oxygen intermediates of resting and stimulated M phi and PMN by luminol-enhanced chemiluminescence. The stimulants applied were: (1) aggregated immunoglobulin (aggIg), (2) zymosan, (3) zymosan opsonized with autologous serum, (4) phorbol myristate acetate (PMA), and (5) concanavalin A (ConA). We found no difference between patients and controls in the generation of oxygen intermediates by resting M phi and PMN. Stimulation by aggIg and zymosan yielded an increased chemiluminescent response in psoriatic M phi and PMN. Serum-treated zymosan effected increased light generation in M phi but not in PMN of patients. By contrast, PMA, and in particular ConA, brought about markedly increased generation of oxygen intermediates in PMN only of patients with psoriasis. Our results indicate control of the increased generation of oxygen intermediates of M phi and PMN by different stimuli. The metabolic events underlying the augmented phagocytic response may be similar to abnormalities found in involved psoriatic skin.