Increased IgG Fc and C3 rosette-forming capacity of granulocytes from patients with psoriasis

Reduced expression of surface receptors for synthetic N-formylated chemotactic oligopeptides by stimulated peripheral blood neutrophils in psoriasis

Receptors for synthetic N-formylated chemotactic peptides on peripheral blood neutrophils were studied by the binding of fluorescein-labeled hexapeptide (N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys) to the cells in vitro at the range of concentrations 0.01-100 nM. Mean fluorescence of neutrophils was quantitated by a flow cytometry using FACS III. Comparison was made between 27 patients with psoriasis vulgaris and 14 normal controls. Various receptor states related to cell activities were induced by different temperatures, by incubation of cells with cytochalasin B and by preincubation with nonlabeled N-formyl-Met-Leu-Phe. This allowed us to distinguish between the specific binding of fluoresceinated hexapeptide to plasma membrane receptor already present (0 degree C), modulation of receptors by peptide and cytochalasin B stimulated degranulation (25 degrees C), and net binding, including internalization of peptide and receptor recycling system (37 degrees C). At peptide concentrations of 1-10 nM, the labeling of neutrophils at 25 degrees C and 37 degrees C, but not at 0 degree C, was found to be about 10-35% lower in psoriatic than in healthy subjects (p less than 0.002). The amount of fluorescein-labeled peptide bound to the cells at 25 degrees C was markedly increased by cytochalasin B, but to a much lower extent in psoriatic patients than in normal controls. Although the number of plasma membrane receptor for chemotactic peptides in the nonstimulated neutrophils was not altered in psoriasis, the receptor up-regulation induced by preincubation of the cells with 1-10 nM of nonlabeled N-formyl-Met-Leu-Phe at 37 degrees C was reduced when measured by subsequent fluoresceinated hexapeptide uptake at 0 degree C. Receptor recycling, as measured by an increase with time (0-30 min) in the binding of chemotactic peptide by neutrophils in which receptors had been down-regulated, was found to be within normal range in patients with psoriasis. These data indicate that nonstimulated, circulating neutrophils have a normal number of chemotactic peptide receptors on the cell surface, but are less able to recruit intracellular receptors to the cell surface. This finding may be related to smaller internal pools or less efficient translocation of these receptors.

Decreased extracellular release of granule enzymes from in vitro-stimulated polymorphonuclear leukocytes in guttate psoriasis

In vitro degranulation of polymorphonuclear leukocytes, which were stimulated either with synthetic chemotactic peptide (N-formyl-methionyl-leucyl-phenylalanine, FMLP) or with C3b-opsonized zymosan as a promotor of phagocytosis, was studied in 66 patients with psoriasis, 18 lesion-free psoriatics, 18 healthy subjects, and 14 other dermatological disorder controls. Stimulated release of lysozyme (from specific granules and azurophil granules) and beta-glucuronidase (from azurophil granules) in the presence of both FMLP and serum-activated zymosan was markedly reduced in patients with actively spreading guttate psoriatic lesions, in whom relapse of lesions lasted for less than 1 month and papules involved about 13-25% of skin surface. In contrast, stimulated degranulation was within normal range in active plaque psoriasis, stationary plaque psoriasis, symptomless psoriatics, and patients with disseminated eczema. Spontaneous release of lysozyme and beta-glucuronidase (background) was found to be not different in all groups studied; however, patients with active guttate psoriasis had significantly lower total lysozyme activity than those with active and stationary plaque psoriasis as well as psoriatics in the remission. These data are in favor of in vivo activation of neutrophils in active guttate psoriasis by some factors related to the early relapse of the lesions. This results in a possible combination of the following phenomena: (1) in vivo partial degranulation of neutrophils; (2) induction of "unresponsiveness state" of these cells to subsequent in vitro stimulation; and/or (3) migration of highly responsive neutrophils to skin lesions, which leaves in the circulation the subpopulation less reactive to chemotactic and phagocytic stimuli.