Polymorphonuclear leukocyte function in psoriasis: chemotaxis, chemokinesis, beta-adrenergic receptors, and proteolytic enzymes of polymorphonuclear leukocytes in the peripheral blood from psoriatic patients

Oral dimethyl fumarate induces changes within the peripheral neutrophil compartment of patients with psoriasis that are linked with skin improvement

BACKGROUND

Dimethyl fumarate (DMF) is a treatment for moderate-to-severe psoriasis and multiple sclerosis. DMF therapy typically improves skin inflammation within the first 3 months of treatment. DMF is a prodrug that generates the hydroxycarboxylic acid receptor 2 (HCA2) agonist, monomethyl fumarate (MMF). Despite widespread clinical use, DMF's mechanism of action is not fully understood.

OBJECTIVES

We wished to characterize the changes induced by DMF in peripheral neutrophils within the first 3 months of treatment to better understand its early antipsoriatic effects.

METHODS

Flow cytometry was used to assess T-cell and neutrophil frequencies, apoptosis and activation phenotype. In vitro culture of neutrophils with DMF and MMF was used to evaluate apoptosis and HCA2 internalization. Serum levels of neutrophil degranulation products were measured by enzyme-linked immunosorbent assay.

RESULTS

Patients with psoriasis had significantly higher leucocyte counts at baseline compared with controls, with a large population of pro-inflammatory CD62L^lo  CD11b^bright neutrophils. Analysis revealed that DMF treatment reduced the frequency of CD62L^lo  CD11b^bright neutrophils and serum levels of neutrophil activation markers. This reduction was not linked to increased apoptosis.

CONCLUSIONS

Our results reveal a novel in vivo effect of DMF therapy on pro-inflammatory neutrophils that likely contributes to this treatment's antipsoriatic efficacy.

The role of neutrophils in neuro-immune modulation

Neutrophils are peripheral immune cells that represent the first recruited innate immune defense against infections and tissue injury. However, these cells can also induce overzealous responses and cause tissue damage. Although the role of neutrophils activating the immune system is well established, only recently their critical implications in neuro-immune interactions are becoming more relevant. Here, we review several aspects of neutrophils in the bidirectional regulation between the nervous and immune systems. First, the role of neutrophils as a diffuse source of acetylcholine and catecholamines is controversial as well as the effects of these neurotransmitters in neutrophil's functions. Second, neutrophils contribute for the activation and sensitization of sensory neurons, and thereby, in events of nociception and pain. In addition, nociceptor activation promotes an axon reflex triggering a local release of neural mediators and provoking neutrophil activation. Third, the recruitment of neutrophils in inflammatory responses in the nervous system suggests these immune cells as innovative targets in the treatment of central infectious, neurological and neurodegenerative disorders. Multidisciplinary studies involving immunologists and neuroscientists are required to define the role of the neurons-neutrophils communication in the pathophysiology of infectious, inflammatory, and neurological disorders.

Decreased expression levels of L-selectin on subsets of leucocytes and increased serum L-selectin in severe psoriasis

L-selectin is a leucocyte adhesion molecule involved in leucocyte interactions with vascular endothelial cells. Following leucocyte activation L-selectin is endoproteolytically released from the cell surface. To assess whether psoriasis vulgaris results in systemic leucocyte activation, we examined expression levels of L-selectin on subsets of peripheral blood leucocytes from patients with psoriasis (n = 25) and normal control subjects. Serum levels of soluble L-selectin were quantified by ELISA in patients with psoriasis (n = 75), pustulosis palmaris et plantaris, and contact dermatitis, as well as normal control subjects. Psoriasis severity was evaluated by psoriasis area and severity index (PASI). L-selectin expression levels on CD4+ T cells, B cells, monocytes, and neutrophils from patients with severe-type psoriasis (PASI > or = 15) was significantly decreased compared with leucocytes from normal control subjects. Furthermore, L-selectin expression on CD4+ T cells showed good inverse correlation with PASI scores. Monocyte L-selectin expression was restored when the skin lesions of psoriasis were remitted. The frequencies of L-selectin+ CD4+ T cells or L-selectin+ CD8+ T cells from patients with psoriasis were almost normal. Serum L-selectin levels in patients with severe-type psoriasis were significantly higher than those in normal control subjects. These results suggest that subsets of leucocytes may be activated in psoriasis, and that L-selectin expression levels on some leucocyte subsets, especially CD4+ T cells, tend to correlate with disease severity of psoriasis.

Neutrophil functions and IL-8 in psoriatic arthritis and in cutaneous psoriasis

The aim of this study is to determine some functions of neutrophil in patients affected by psoriatic arthritis and to compare them to those of patients affected by cutaneous psoriasis and to normal controls. We used a model of experimental cutaneous inflammation allowing to separate a cluster of purified and viable PMN cells. Then we analyzed, within the three groups, the IL-8 concentration in serum and in the supernatant obtained from the inflammatory site to gather data on the possible pathogenic role played by this cytokine in psoriatic arthritis. We studied neutrophil functions in patients with cutaneous psoriasis and psoriatic arthritis, in acute phase, in comparison with healthy control subjects. We investigated in vivo neutrophil migration by Senn's skin window technique and measured adhesion assay and superoxide production in circulating and migrating neutrophils after different stimuli. We also measured IL-8 concentration in serum and in the supernatant obtained from the inflammatory site, artificially created through the skin window scrape. Neutrophil migration in vivo was significantly higher in both groups of patients than in controls. In the presence of fMLP, blood cells showed a burst of superoxide release, which was significantly more pronounced in patients when compared to healthy controls. Neutrophils from skin window scrape showed a much higher response to fMLP as compared to blood cells of all subject groups, but no differences were observed between patients and controls. No correlation was found between the three groups in adhesion ability under basal condition or in response to different stimuli by circulating and migrating neutrophils. Our results also show a great increase of IL-8 in the exudate from patients compared to controls. Our study shows that there is no difference in neutrophil functions between patients with psoriatic arthritis and cutaneous psoriasis; moreover we suggest that the source of high IL-8 levels are neutrophils rather than the keratinocytes.

Eosinophil cationic protein (ECP) level and its correlation with eosinophil number or IgE level of peripheral blood in patients with various skin diseases

Eosinophil cationic protein (ECP) is a cationic protein derived from eosinophil granulocytes, and has been studied mainly in atopic diseases and considered as a useful marker of disease activity in atopic dermatitis. We measured the serum ECP levels in patients with various skin diseases (n = 875) and in normal healthy controls (n = 79), and evaluated the correlation between ECP level and blood eosinophil number, or ECP and IgE levels. Serum ECP levels were significantly higher in patients with drug eruption (15.8 +/- 1.7 micrograms/l), psoriasis (15.1 +/- 6.0 micrograms/l), acute urticaria (13.9 +/- 1.4 micrograms/l) than in healthy controls (4.5 +/- 0.3 micrograms/l) (P < 0.05) and also significantly elevated in patients with elevated eosinophil numbers (15.2 +/- 1.0 micrograms/l) compared to those in patients with normal eosinophil numbers (8.8 +/- 0.3 micrograms/l) (P < 0.001). Serum ECP level and eosinophil number in peripheral blood were also correlated in patients with psoriasis (gamma = 0.82, P < 0.01), drug eruption (gamma = 0.31, P < 0.01) and acute urticaria (gamma = 0.20, P < 0.05). However, no correlation between ECP and IgE levels in all of the patients was found. Among the patients with chronic urticaria, ECP levels showed an increasing trend in patients with angioedema, cold urticaria and dermographic urticaria as compared with those in healthy controls. Our results suggest that, even though the role of ECP released from activated eosinophils is still unknown, its measurement might be of help to understand the pathogenesis of some skin disorders.

The eosinophil granulocyte in psoriasis

The presence of eosinophils and eosinophil cationic protein (ECP) in the involved and non-involved skin in patients with psoriasis was studied using a polyclonal antibody specific for ECP and a monoclonal antibody (EG2) specific for activated eosinophils and secreted ECP. ECP immunoreactive eosinophils were found in all the specimens from involved psoriatic skin. In new lesions in patients with rapidly progressive disease, intense ECP immunoreactivity was detected both intra- and extracellularly, particularly in the upper third of the epidermis and usually in association with granulocytes. In stable or slowly progressive lesions, less ECP was observed. The EG2-immunoreactivity was positive in the same areas. ECP was also determined in suction-blister fluid from lesional and non-involved skin in psoriasis patients and in healthy subjects. The ECP concentration was greatly elevated in the fluid from lesions in patients with more acute and progressive disease.

Leukotriene B4-induced permeability increase in postcapillary venules and its inhibition by three different antiinflammatory drugs

Leukotriene B4 (LTB4) is a potent chemotactic and chemokinetic substance that causes leukocyte accumulation and increases vascular permeability. We have used the hamster cheek pouch model to study the effect of some different antiinflammatory drugs on the LTB4-induced microvascular permeability. Intravascular fluorescein-labeled dextran (mol wt 150,000) was used as a tracer of macromolecular leakage, which was measured as the number of venular leaky sites and as efflux of the vascular tracer. Topical application of LTB4 (10(-8) M, 5 min) resulted in a reversible increase of the vascular permeability and could be repeated with 40-min intervals without any significant reduction in permeability response. The LTB4-induced response could be inhibited by budesonide (a glucocorticoid) given locally, by iloprost (a prostacyclin analog) given intravenously and by a combined local and intravenous treatment with terbutaline (a beta 2-receptor agonist) but not by local terbutaline treatment only.

Superoxide dismutase and myeloperoxidase activity in polymorphonuclear leukocytes, and serum ceruloplasmin and copper levels, in psoriasis

The levels of superoxide dismutase (SOD) and myeloperoxidase (MPO) in polymorphonuclear leukocytes (PMN), and serum ceruloplasmin activity and copper content, were measured in 60 patients with psoriasis and 33 healthy controls. There were no significant differences in the activity of MPO between the patients and the controls. However, SOD activity in PMN was significantly lower in the patients than in the controls. Serum ceruloplasmin activity and copper levels were significantly higher in the psoriatics than in the controls.

Studies of polymorphonuclear migration into psoriatic skin using a new in vivo method

A new method, employing a skin-implanted cell trap already used to study chemotaxis in cancer patients, was applied to 35 healthy volunteers and 12 psoriatic patients. A dacron disk impregnated with 10 microliters of 4-6.10(6) live BCG suspension was implanted in the deep dermis. After 24 h the disk was removed, and five sections of each disk were counted for polymorphonuclear leukocytes (PMNs) and monocytes. Involved and uninvolved psoriatic skin showed a decrease of PMN migration into the disk as compared with controls. No difference could be demonstrated between involved and uninvolved skin. Mononuclear cell chemotaxis was the same in psoriasis as in controls. These results are in agreement with other in vivo data using mainly the skin chamber technique indicating a decrease of PMN chemotaxis in psoriatic skin at 24 h.

Plasma lactoferrin reflects neutrophil activation in psoriasis

We used a biotinylated antibody ELISA technique to measure plasma levels of lactoferrin (LF) and the LF content of peripheral blood PMN in 20 patients with psoriasis, 21 with eczema or other inflammatory skin conditions, 19 patients with malignant skin tumours and 20 healthy control individuals. In psoriasis, plasma LF levels were significantly increased compared with levels in the other skin conditions and in the healthy controls (P less than 0.01). Furthermore, in psoriasis the LF content of circulating PMN was decreased. These findings provide further evidence that in psoriasis systemic activation ('priming') of circulating PMN may take place.

A speculative on psoriasis as an evolutionary consequence

I speculate that if the inflammatory reactivity of all humans were quantitated, the results would fall on a bell-shaped curve. Psoriasis or the psoriatic trait is the most reactive 3%. Any attempt by evolution to shift the general inflammatory response to lesser activity would result in consequences more significant than psoriasis. This speculation predicts that we might have to settle for quantitative rather than qualitative changes in inflammation in 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.

Circulating immune complexes in untreated psoriasis. A comparison of Raji-cell radioimmunoassay and polymorphonuclear leukocyte phagocytosis

Three different in vitro assays for the demonstration of circulating immune complexes were compared in 49 patients with psoriasis. Granulocytes from psoriatic subjects contained immune complex-like material in 25 patients (51%). When psoriatic serum was incubated with granulocytes from healthy blood donors, phagocytosed material was found in 18 patients (37%). The Raji-cell assay was only positive in two of 27 subjects (7%). Of the patients 71% tested positively with one of the granulocyte phagocytosis tests. Both tests were positive simultaneously in 16% and negative in 29% of the patients. The pathogenetic significance of the immune complex-like material is unclear.

SC-39026, a specific human neutrophil elastase inhibitor

SC-39026, (+/-) 2-chloro-4-(1-hydroxyoctadecyl)benzoic acid, inhibits human neutrophil elastase with an IC50 of 0.5 microM (KI of 1.5 microM). Its inhibition of elastase is reversible and noncompetitive at low concentrations (0.5-1.25 microM). Inhibition is "mixed" at higher inhibitor concentrations. SC-39026 is inactive against hog pancreatic elastase, bovine alpha-chymotrypsin and Pseudomonas aeruginosa elastase, but does inhibit human neutrophil cathepsin G with an IC50 of approximately 2.5 microM. Neutrophil elastases isolated from rat, hamster, rabbit and hog are also inhibited by SC-39026.

Neutrophil leukocyte morphology, cigarette smoking, and palmoplantar pustulosis

Neutrophil leukocyte morphology was examined in whole blood films from 20 patients with palmoplantar pustulosis (PPP) and 32 healthy controls. In the PPP patients, there was a significant increase in the number of neutrophils having polarized morphology or membrane ruffling; however, there was no significant difference in neutrophil morphology between cigarette smokers and nonsmokers, suggesting that the epidemiologic link between smoking and PPP is not explained by increased polarization of peripheral blood neutrophils.

Polymorphonuclear leukocyte function in psoriasis vulgaris

Polymorphonuclear leukocyte (PMN) migration was assessed in vitro using the agarose plate method in patients with psoriasis vulgaris, and compared with an age- and sex-matched control group. No significant difference was found between the two groups in the PMN response to the chemotactic substances F-Met-Leu-Phe (FMLP) or zymosan activated serum (ZAS). Equally, the chemokinetic or chemotactic potential of psoriatic serum did not differ from control serum. Our results do not support a primary abnormality of PMN function in psoriasis.

Neutrophil locomotion and serum chemotactic and chemokinetic activities in pustulosis palmoplantaris compared with psoriasis

Twenty patients with palmoplantar pustulosis (PPP) and 21 patients with psoriasis were compared with respect to the chemotactic response and random migration of their neutrophils (PMNs) and to the chemotactic and chemokinetic activities of their serum. The Boyden chamber technique was used. Compared with the reference group, the PPP neutrophils showed a significant decrease in random migration (p = 0.036) and chemotactic response to casein (p = 0.031), but not to zymosan-activated serum. The psoriasis PMNs had normal chemotactic response, but decreased random migration (p = 0.001). The chemokinetic effects of serum from PPP and psoriatic patients on normal neutrophils were increased (for PPP, p = 0.019 and for psoriasis p = 0.024). The chemokinetic activity of the heated sera was decreased and inversely correlated to the serum level of IgA in both disorders (PPP, p = 0.021; psoriasis, p = 0.013). The chemotactic activity of serum on normal PMNs was decreased in both conditions (PPP, p = 0.001; psoriasis, p = 0.047); this was due to the presence of chemotactic factor inhibitors in 34% of the sera. It seems likely that the high chemokinetic effect of serum both from the PPP and from the psoriasis patients compensates for the slightly low or normal migratory activity of neutrophils from these patients.

The enhanced monocyte and neutrophil chemotaxis in psoriasis is normalized after treatment with psoralens plus ultraviolet A and anthralin

The chemotactic activity of purified monocytes and neutrophils was studied in twenty-two psoriatic patients prior to the initiation of psoralens plus ultraviolet A (PUVA) or anthralin therapy and during the treatment. Patients with untreated, active psoriasis had increased chemotactic response of their monocytes and neutrophils to N-formyl-methionyl-leucyl-phenylalanine. Plasma from untreated psoriasis patients had an enhanced chemotactic activity toward neutrophils from persons without psoriasis. Treatment with PUVA or anthralin resulted in a progressive clearing of psoriatic lesions and in a significant depression of leukocyte chemotaxis 2 weeks after the start of the respective therapy. The chemotactic activity of both monocytes and neutrophils was normalized after 4 weeks of anthralin therapy and after 6 weeks of PUVA treatment. The chemotaxis-enhancing properties of plasma from psoriasis patients returned to normal values already after 2 weeks of treatment.

Psoriasis and leukocyte chemotaxis

Transepidermal migration of leukocytes, with resultant formation of microscopic or macroscopic sterile subcorneal pustules is a phenomenon characteristically noted in psoriasis and related sterile pustular dermatoses. It is natural to assume the presence of potent neutrophil chemotactic substances in the subcorneal portion of the lesional epidermis, because this location is the target of the in vivo leukocyte chemotaxis. In fact, crude psoriasis scale extracts show remarkably high neutrophil chemotactic and activating properties as compared with those of other non-psoriatic inflammatory dermatoses. We isolated a psoriatic leukotactic factor (PLF) having a molecular mass of around 12 kD, distinct from those common to other inflammatory changes involving the skin or those released by bacteria. Further analysis of PLF identified C5 cleavage fragments, together with other chemotactic peptides, such as those derived from monocytes. Likewise, potent low-molecular-mass chemotactic factors, including cell membrane lipid derived chemotactic factor, e.g. leukotriene B4, are also increased in psoriatic lesions, as in other nonpsoriatic inflammatory dermatoses. However, their activity to stimulate the generation of oxygen radicals in neutrophils was found to be much weaker than that of PLF. The peripheral blood leukocytes from active psoriatic patients show enhanced function in chemotaxis, phagocytosis, active oxygen production, and enzyme release; patients' sera contain substances such as anaphylatoxins that activate leukocyte function. Further research is required for clearer understanding of the series of events resulting in the leukocyte chemotaxis, as well as for the elucidation of the background immunoregulatory mechanisms.

Monocyte and neutrophil chemotaxis in psoriasis. Relation to the clinical status and the type of psoriasis

Chemotactic activity of purified monocytes and polymorphonuclear leukocytes was studied in fifty patients with psoriasis vulgaris and in forty-five healthy individuals by an objective in vitro assay with the use of a 51Cr-labeling technic. Both monocytes and polymorphonuclear leukocytes showed a statistically significant increase in chemotactic response, which was positively correlated with disease activity but not with the extent of the cutaneous lesions. The chemotactic activity of monocytes correlated with that of polymorphonuclear leukocytes in the same patients. Exacerbation of psoriasis was preceded by a rapid increase of polymorphonuclear leukocyte chemotaxis, and a decline of chemotaxis occurred during clinical improvement. The psoriatic leukocytes were 22% more sensitive than normal leukocytes to leukotriene B4 than to N-formyl-methionyl-leucyl-phenylalanine. Psoriatic plasma showed chemotaxis-enhancing properties, but only in patients with widespread cutaneous lesions. Additionally, monocyte and polymorphonuclear leukocyte chemotaxis was studied in twenty patients with pustular psoriasis and in fifteen patients with psoriatic arthritis. The chemotactic profiles in pustular psoriasis were different from those in psoriasis vulgaris. Patients with pustular psoriasis had significantly higher polymorphonuclear leukocyte chemotaxis than patients with psoriasis vulgaris, but the chemotactic activity of monocytes was normal. The presence of seronegative arthritis had no influence on chemotactic activity of psoriatic leukocytes.

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.

Arachidonic acid metabolism by peripheral blood cells in psoriasis

The metabolism of arachidonic acid by mixed suspensions of leukocytes and platelets prepared from peripheral blood has been studied in 20 patients with psoriasis and 21 healthy controls. A lipoxygenase-derived product, identified as 12,20-dihydroxy-5,8,10,14-eicosatetraenoic acid was formed in increased amounts by the cell suspension from the psoriatic patients. This product results from the metabolism of platelet-derived 12-hydroxy-5,8,10,14-eicosatetraenoic acid by the polymorphonuclear leukocyte 20-hydroxylase enzyme. By contrast, synthesis of the cyclo-oxygenase products 12-hydroxy-5,8,10-heptadecatrienoic acid and thromboxane B2 was diminished. Benoxaprofen, which is known to be beneficial in psoriasis, diminished the levels of 12,20-dihydroxy-5,8,10,14-eicosatetraenoic acid formed in vitro.

Stress, symmetry, and psoriasis: possible role of neuropeptides

The role of stress as a triggering factor in the exacerbation of psoriasis and the clinically symmetric distribution of psoriatic plaques suggested a possible role for neuropeptides in the etiopathogenesis of psoriasis. Several observations by other investigators involving substance P suggested to us a possible role for substance P as a modulator of the inflammatory response in psoriasis. A hypothesis for the role of substance P that would account for the temporal onset with stress, the clinical symmetry of lesions, and the histopathologic features of psoriasis is presented.

Arachidonic acid metabolism by polymorphonuclear leukocytes in psoriasis

The metabolism of endogenous arachidonic acid by human polymorphonuclear leukocytes (PMNL) isolated from peripheral blood has been studied in 19 patients with chronic plaque psoriasis and 19 healthy controls. Using calcium ionophore A23187 as a stimulus, the PMNL synthesized leukotriene B4 (LTB4), 6-trans-leukotriene B4, 12-epi-6-trans-LTB4, and 5-hydroxy-6,8,11,14-eicosatetraenoic acid. There was no significant difference in the amounts of the products formed between the psoriatic and control groups. The elevated levels of LTB4 that have been described in psoriatic skin may therefore be due to the PMNL infiltrate or to enhanced synthesis by another cell type. The reported increase in activity of the circulating PMNL in psoriasis does not appear to be due to increased 5-lipoxygenase activity in these cells.

Leukopheresis for treatment of psoriasis: is therapeutical benefit related to reduced activities of neutral proteinases of polymorphonuclear leukocytes?

Ten patients were treated with repeated leukophereses performed one to three times per week for 2-5 weeks. Two of the patients was cleared completely, four exhibited regression of more than one-half of the lesions, and four showed only a slight improvement. The therapy did not markedly affect the granulocyte count in peripheral blood, and the beneficial clinical response was not related to the number of polymorphonuclear leukocytes (PMNs) removed by leukophereses. During therapy, the activities of elastase, cathepsin G, lysozyme, and myeloperoxidase in PMNs were determined by spectrophotometry. PMNs isolated using a Haemonetics 30 blood-cell separator were about 50% deficient in these activities in comparison to cells obtained directly from peripheral blood. Thus, leukopheresis induces a marked degranulation of PMNs. Repeated leukophereses were found to generate significant variations in the activities of circulating PMN granule enzymes and in the levels of acid-soluble proteins. Remission or great improvement were observed in patients who, during therapy, exhibited decreased PMN elastase and cathepsin G activities, whereas a poor clinical response was accompanied by high enzymatic activities.

Methotrexate inhibits the leukotriene B4 induced intraepidermal accumulation of polymorphonuclear leukocytes

The penetration of polymorphonuclear leukocytes (PMNs) into the epidermis following topical application of leukotriene B4 was assessed in the clinically uninvolved skin of psoriatic patients treated with methotrexate and of psoriatic patients without treatment, and in normal controls. Inhibition of PMN infiltration was observed in those patients treated with methotrexate while there was no significant difference between untreated psoriatic patients and normal controls.

Etretinate therapy reduces polymorphonuclear leukocyte chemotaxis--enhancing properties of psoriatic serum

Using a Boyden chamber technic, we measured the directed chemotaxis of polymorphonuclear leukocytes obtained from control subjects or psoriasis patients when the leukocytes were placed in sera obtained from control subjects or psoriasis patients. The samples from patients were obtained before therapy and after 2 and 4 weeks of etretinate administration. Compared with control sera, the sera from seven untreated psoriasis patients significantly enhanced the chemotaxis of polymorphonuclear leukocytes from control subjects toward a chemotaxin (p less than 0.05). After 4 weeks of etretinate therapy, the chemotaxis-stimulating ability of the sera from psoriasis patients was no longer significantly greater than that of the control sera. This decline in the chemotaxis-stimulating activity of our patients' sera preceded significant clearing of their psoriasis. The levels of circulating etretinate in the blood of our patients could not account for the reduction. Etretinate therapy had no apparent direct effect on the chemotactic activity of polymorphonuclear leukocytes from the psoriasis patients but may act in part by reducing the inflammatory effects of psoriatic sera.

The 'metabolic burst' in polymorphonuclear leukocytes from patients with quiescent psoriasis

We report an investigation of peripheral blood polymorphonuclear leukocytes (PMN) from untreated patients with mild, quiescent psoriasis. Four aspects of the 'metabolic burst' were measured to illustrate phagocytosis-related events. These were: myeloperoxidase activity, hydrogen peroxide release, superoxide production and luminol-amplified chemiluminescence. Our study does not support the concept of an intrinsic abnormality of the PMN in psoriasis, but provides additional evidence for disease activity-dependent changes in phagocytic behaviour. Possible interactions with certain humoral factors, the so-called opsonins, are discussed.

Increased in vivo secretory activity of neutrophil granulocytes in patients with psoriasis and palmoplantar pustulosis

The relationship between psoriasis and palmoplantar pustulosis (PPP) is uncertain, as is the role of the neutrophil granulocyte in these conditions. In a previous comparative study of the rate of polymorphonuclear leucocyte (PMN) phagocytosis of IgG- and IgG-C3b-coated particles, an increased uptake rate was found in both diseases. Further information on the in vivo activity of PMNs in these conditions may be obtainable by determining the level of lactoferrin (LF) in serum from such patients, since LF serves as a specific marker of the turnover and activity of the circulating pool of neutrophils. In this study on 19 patients with psoriasis and 20 patients with PPP, elevated levels of LF were found in both conditions. In contrast, the levels of lysozyme and beta 2-microglobulin, which are markers of monocyte-macrophage and lymphocyte activity, respectively, were normal. This suggests the selective activation of neutrophils in these disorders. LF was significantly correlated (P less than 0.05 and 0.001, respectively) to the rates of phagocytosis of IgG- and IgG-C3b-coated particles, but not to the chemotaxis of isolated PMNs. There was no correlation between the severity of the disease and the levels of serum LF. The data suggest the increased in vivo activity of neutrophils in psoriasis and PPP.

Alpha 1-antitrypsin deficiency genes: contributory defect in a subset of psoriatics?

Since proteolytic processes are prominent in psoriasis, sera of forty-five psoriatics were examined for alpha 1-antitrypsin (alpha 1-AT) phenotype and eighteen sera, for alpha 1-AT content and function. Five sera (11.1%) had heterozygous phenotypes (2 MZ and 3 MS), a prevalence of Z and S variants similar to that reported in nonpsoriatic populations. Two of three variants examined for content and function exhibited marked reductions. Since MZ heterozygotes are almost always, and MS phenotypes sometimes, associated with decreased serum alpha 1-AT levels, and since Z and MZ phenotypes are associated with increased hepatic fibrosis or cirrhosis, these variants may be relevant to problems of spontaneous fibrosis or methotrexate-induced hepatotoxicity in psoriasis. alpha 1-AT deficiency may also contribute to guttate flares with infection and to increased O-2 . production by psoriatic sera-stimulated polymorphonuclear leukocytes (PMNs). Although no evidence exists that psoriasis is more prevalent among persons with hypomorphic alpha 1-AT phenotypes, such defects may contribute to severity of inflammation and hyperplasia.

Neutral proteinases and other neutrophil enzymes in psoriasis, and their relation to disease activity

The activities of elastase, cathepsin G, lysozyme and myeloperoxidase of polymorphonuclear leukocytes were determined by spectrophotometry in thirty-six patients with psoriatic lesions, twelve symptom-free patients with psoriasis and fifteen normal controls. The mean activities of cathepsin G, elastase and lysozyme were found to be increased by 55 to 70% in patients with actively spreading plaque lesions compared with healthy controls (P less than 0.01). Most patients with guttate lesions had total enzyme activities within the normal range. Those with stationary plaque psoriasis had activities of both neutral proteinases (cathepsin G and elastase) which were about 40% lower than normal controls (P less than 0.05). In the lesion-free psoriatics, the activities of neutral proteinases were about 70% of control values. Our findings emphasize the importance of assessment of disease activity in this sort of investigation. The present data may help to resolve much of the confusion regarding PMN function in psoriasis.