cytochalasin-b and 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.

Topics: Adolescent; Adult; Aged; Cytochalasin B; Female; Gene Expression Regulation; Humans; Male; Middle Aged; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Oligopeptides; Protein Processing, Post-Translational; Psoriasis; Receptors, Formyl Peptide; Receptors, Immunologic; Temperature

Chemotactic activities of circulating polymorphonuclear leukocytes (PMN) were determined in twenty patients with psoriasis and twenty healthy control persons. After serial dilution of the complement split product C5a and the formylated tripeptide f-met-leu-phe (FMLP), chemotaxis profiles showed that PMN migration toward both chemotaxins was significantly increased in psoriasis. In addition, PMN from psoriatic patients responded to chemotaxins at much lower concentrations compared with controls. The liberation of (lysosomal) beta-glucuronidase was also determined in cytochalasin B-treated cells confronted with increased concentrations of the chemotaxins. Secretion of this marker enzyme started at lower concentrations in PMN derived from psoriatic patients. Our observations demonstrate migratory and secretory hyper-responsiveness of PMN from psoriatic patients. This may play a role in perpetuating the psoriatic tissue reaction.

Topics: Adult; Aged; Chemotactic Factors; Chemotaxis, Leukocyte; Complement C5; Complement C5a; Cytochalasin B; Cytoplasmic Granules; Female; Glucuronidase; Humans; Male; Middle Aged; N-Formylmethionine; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Oligopeptides; Psoriasis