Inflammatory and immune cell function in psoriasis--a subtle disorder I. In vivo and in vitro survey

Immunotherapy of Psoriasis

Background:

Psoriasis is a common inflammatory skin disease, characterized by epidermal keratinocyte hyperproliferation and an inflammatory infiltrate. Current research indicates that epidermal hyperproliferation is, in part, dependent upon the milieu of cytokines and growth factors produced chiefly by T cells within the infiltrate and that the T cells play a central role in the pathogenesis of psoriasis.

Objective:

Recent developments in the treatment of psoriasis are discussed in the context of current understanding of the pathogenesis of this condition.

Conclusion:

Significant advances are being made in the treatment directed against these specific immunologic aberrations. Efficacy of immunosuppressive agents such as cyclosporine, FK506 (tacrolimus), anti-CD4 monoclonal antibodies, and IL-2 fusion-toxin in the treatment of psoriasis underscore its probable immune basis. Highly specific treatment directed against cytokines, angiogenesis, and adhesion molecules remains experimental, but shows promise for safer systemic treatment in the future.

Disease concomitance in psoriasis

BACKGROUND

Psoriasis is a multifactorial disease of unknown origin.

OBJECTIVE

Our purpose was to determine the frequency of skin disorders concomitantly seen in patients with psoriasis.

METHODS

We analyzed data from more than 40,000 patients and calculated sex- and age-adjusted ratios of expected and observed incidence rates of associated disorders.

RESULTS

The results demonstrate that, compared with age-matched control patients without psoriasis, cutaneous immune disorders such as allergic contact dermatitis, atopic dermatitis, and urticaria are underrepresented in patients with psoriasis. In contrast, certain systemic disorders such as diabetes, heart insufficiency, and obesity occur significantly more often in patients with psoriasis than in control subjects. Increased resistance to cutaneous bacterial infections was noted only in patients with early-onset psoriasis.

CONCLUSION

Our observations show that a distinct pattern of associated diseases exists in patients with psoriasis. Although systemic disorders such as obesity, diabetes, and heart disease may be related to dietary habits and nutritional status, the relative resistance to cutaneous infections together with decreased immune responsiveness suggest a genetically determined selection.

Monocyte adhesion to fibronectin in psoriasis

BACKGROUND

After vascular extravasation, mononuclear cells (MNC) undergo chemotaxis and adhesion to extracellular matrix proteins, resulting in their differentiation into macrophages. Although endothelial adhesion and chemotaxis are altered in psoriasis, MNC adhesion to extracellular matrix proteins has not been previously studied in the disease. Since MNC adhesion to endothelial cells is abnormally regulated in psoriasis by TGF-beta, we tested they hypothesis that in psoriasis substance P also regulates the adhesion of monocytes to the extracellular matrix protein fibronectin.

METHODS

Monocytes from 16 normal controls and 11 psoriatic individuals were isolated and purified using a two-step gradient centrifugation procedure. Adhesion to fibronectin was studied by plating monocyte suspensions onto fibronectin-precoated microtiter plates. The number of adherent cells was quantified by measuring their hexosaminidase activity.

RESULTS

Although statistically significant differences in the basal (unstimulated) adhesion or in the substance P-stimulated adhesion between normal control monocytes and those obtained from psoriatic individuals were not observed, a subpopulation of psoriatics was identified who responded to substance P. Furthermore, this in vitro response to substance P was correlated with the clinical status of the subpopulation which was characterized by unstable psoriasis triggered by stressful life events.

CONCLUSIONS

The results of this study indicate that priming of monocytes by the extracellular matrix protein fibronectin or by elevated levels of substance P are not critical steps in the pathogenesis of stable, chronic psoriasis. Substance P may contribute to the appearance of new lesions in some individuals with unstable psoriasis.

Increased IL-6 production by monocytes and keratinocytes in patients with psoriasis

Interleukin-6 (IL-6) is a multifunctional inflammatory cytokine that is produced by monocytes and keratinocytes upon stimulation. Because psoriasis is a skin disease characterized by a hyperproliferative activity of keratinocytes and an inflammatory infiltrate, in the present study IL-6 production of monocytes and keratinocytes of patients with psoriasis was investigated. Peripheral blood mononuclear cells (PBMC) derived from psoriatics, atopics, and healthy controls were incubated for 24 h and, subsequently, supernatant IL-6 activity was measured using an IL-6-dependent hybridoma cell line (B9). Compared to controls and atopics, PBMC of psoriatics produced significantly increased amounts of biologically active IL-6. These findings were also confirmed by Western blot analysis using a specific antiserum directed against IL-6. Moreover, when the sera of the same patients were tested for IL-6 activity, sera of psoriatics contained significantly elevated amounts of circulating IL-6 in comparison to samples from atopics and healthy controls. In contrast to normal or uninvolved skin, keratinocytes in psoriatic lesions were remarkably positive for IL-6 as detected by immunohistochemistry and in situ hybridization. In addition, IL-6 also was found to induce its own synthesis and release by monocytes. These findings indicate that keratinocytes and monocytes in psoriasis are activated to produce increased amounts of IL-6, which may be one of the mediators involved in the regulation of both local and systemic inflammatory reactions occurring in skin diseases such as psoriasis.

Altered cell-mediated immunity to group A haemolytic streptococcal antigens in chronic plaque psoriasis

The proliferative lymphocyte response to sonicated group A, beta-haemolytic streptococci (Strep-A) was measured by thymidine incorporation in 78 patients with psoriasis (guttate, chronic plaque or both). Lymphocytes from 72 of these patients were also cultured with streptokinase/streptodornase (SK/SD), and 20 of the patients with chronic plaque psoriasis were further tested with PPD, Candida albicans and sonicated Streptococcus mutans, a bacterial type not associated clinically with psoriasis. The median stimulation index (SI) of the psoriasis group to the Strep-A preparation was significantly higher than that of a group of 27 non-psoriatic individuals (P less than 0.05). Within this group, only the patients with chronic plaque psoriasis (n = 42) showed a significantly increased proliferative response compared to the non-psoriatic controls (median SI = 123.8 and 31.9, respectively, P less than 0.01). Although the lymphocyte response of the chronic plaque group to SK/SD was also markedly higher than that of the control group, this difference did not reach statistical significance. In addition, these patients did not show significantly increased responses to any of the other antigens tested, including S. mutans. No correlation was observed between the degree of proliferation to Strep-A and disease extent or activity. Similarly, ASO titres, which were raised in 11 out of 23 guttate and three out of nine chronic plaque psoriasis patients tested, did not correlate with the proliferative responses observed.

Cyclosporine for plaque-type psoriasis. Results of a multidose, double-blind trial

BACKGROUND

Severe plaque-type psoriasis has been successfully treated with orally administered cyclosporine, but there has been no comparative, controlled evaluation of various dosages and their efficacy and side effects.

METHODS

In a 16-week, double-blind trial, we randomly assigned 85 patients with severe psoriasis to receive 3, 5, or 7.5 mg of cyclosporine per kilogram of body weight per day or a placebo consisting of the vehicle for the drug. After eight weeks the dose could be adjusted to improve safety or efficacy while maintaining blinding.

RESULTS

The psoriasis improved in a dose-dependent fashion. After eight weeks of fixed-dose therapy, 36, 65, and 80 percent of the patients receiving 3, 5, and 7.5 mg of cyclosporine per kilogram per day, respectively, were rated as being clear or almost clear of psoriasis; each group had significant improvement (P less than 0.0001) as compared with the group receiving vehicle, in which none of the patients were rated as clear or almost clear. The patients who received 5 mg per kilogram were the least likely to require dosage adjustments because of side effects or a lack of efficacy. The glomerular filtration rate, measured in a subgroup of 34 patients receiving cyclosporine, decreased by a median of 16 percent. Higher doses of cyclosporine had greater adverse effects on systolic blood pressure, glomerular filtration rate, and serum levels of creatinine, uric acid, bilirubin, and cholesterol. Delayed-type hypersensitivity reactions to skin-test antigens were reduced by cyclosporine administration. Cyclosporine appears to become concentrated in skin.

CONCLUSIONS

Cyclosporine therapy leads to a rapid and thorough clearing of psoriasis; an initial dose of 5 mg per kilogram per day seems to be appropriate. However, the safety of cyclosporine for the long-term treatment of psoriasis remains to be determined.

Characterization of skin-infiltrating lymphocytes in patients with psoriasis

In this study, skin-infiltrating cells in psoriasis patients were characterized in biopsies from both involved and uninvolved skin. Histologic examination of biopsies showed the presence of both CD4+ and CD8+ T cells and the lack of B lymphocytes. Skin biopsies were also placed in tissue culture medium supplemented with human serum, interleukin-2 (IL-2), and irradiated autologous blood lymphocytes. T lymphocytes grew from both plaques and univolved skin biopsies and consisted of a heterogeneous population of T-cell subsets. The immunophenotypic analysis of cultured cells was comparable to the histologic examination on frozen section, i.e., there was a greater number of CD4/CDw29+ cells than CD8+/CD45+ cells. Cultures were tested in the primed lymphocyte test (PLT) and cell-mediated lympholysis (CML) assays. All cultures tested demonstrated secondary proliferative but not cytolytic reactivity. The PLT results indicate that the cell cultures generated are autoreactive. This autoreactivity was found to be directed against non-human leukocyte antigens (HLA), i.e., minor HLA with some restriction to major HLA antigens.

Differential effects of cyclosporine A on Langerhans cells and regulatory T-cell populations in severe psoriasis: an immunohistochemical and flow cytometric analysis

Systemic administration of cyclosporine A (Cy-A; initial dose 5 or 2.5 mg/kg/day) to patients with severe chronic plaque psoriasis produced marked reductions in psoriasis area and severity index within 4 weeks. The clinical response was accompanied, within 1 week, by progressive reductions in T-cell subpopulations (CD3+ and CD4+) and in numbers of interleukin-2 receptor (IL-2-R)-positive (CD25+) cells within lesional skin. Over the first 4 weeks of treatment, these changes were accompanied by reductions in DR+ cells within the epidermis (minor) and dermis (substantial). In contrast, numbers of epidermal CD1+ cells increased substantially during resolution of the skin lesions. Unlike lesional skin, however, no significant changes in absolute numbers of circulating immunoregulatory T-cell populations, including helper/inducer (CD45R) and suppressor/inducer (CD29W) subsets, quantified by dual immunofluorescence labelling, were detected. Moreover, numbers of blood-borne HLA-DR, IL-2-R and transferrin receptor (CD71) positive lymphocytes were unaffected by Cy-A therapy, nor were any differences detected between psoriatic patients and normal controls using these cell markers. Our data suggest that the immunoregulatory effects of Cy-A in psoriasis are mediated via lesional T lymphocytes and that epidermal CD1+ DR- dendritic cells may play an influential role in the regulation of T-cell function and keratinocyte growth during resolution of the skin lesions.

Hypothesis--the natural selection of psoriasis

The high genetic frequency of some inherited disorders may in part be related to a survival advantage conferred against an environmental hazard. Psoriasis is an inherited disorder which is common amongst populations of northern latitudes. Cutaneous delayed-type hypersensitivity response to streptococcal antigen is altered in such patients with a decrease in induration and erythema. Scarlet fever has until recently been associated with a high childhood mortality, the pathogenesis of which is related to interdependent primary toxicity and secondary toxicity (including delayed-type hypersensitivity) to streptococcal antigen (erythrogenic toxin), leading to cellular damage and potentially lethal shock. Streptococcal infection, usually presenting as pharyngitis, is a classical trigger for both scarlet fever and psoriasis. Individual susceptibility to scarlet fever has been clinically assessed in the past by the Dick test--an intradermal injection of the filtrate of a broth culture of scarlatina-producing strains of Streptococcus giving an erythematous reaction at 24-48 h (Dick-positive). The degree of reaction is directly related to susceptibility to scarlet fever. The severity of and mortality from scarlet fever may be ameliorated by immunological mechanisms also found in psoriatic patients. The high prevalence of psoriasis amongst some populations today may be related to such a protective factor.

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.

Psoriatic arthritis and acquired immunodeficiency syndrome

We describe 2 patients who developed psoriatic arthritis during the course of acquired immunodeficiency syndrome. Both patients developed skin and articular involvement characteristic of psoriatic arthritis; these manifestations were refractory to conventional therapy. Our findings suggest that psoriatic arthritis should be added to the expanding spectrum of musculoskeletal manifestations of the acquired immunodeficiency syndrome.

Immunologic mechanisms in psoriasis

This review presents evidence for the immunopathogenesis of psoriasis. T lymphocytes with human lymphocyte antigen (HLA)-DR molecules and receptors for interleukin 2 were found in the dermis of psoriatic plaques, suggesting the presence of activated T cells in these lesions. Keratinocytes in active plaques demonstrated HLA-DR molecules on their surfaces. These immunologic abnormalities were reversible with medical therapy. Keratinocyte HLA-DR expression was associated with an increased incidence of psoriatic arthritis. We propose that HLA-DR + keratinocytes and Langerhans cells in plaques could activate dermal T cells directly in an autologous mixed leucocyte/epithelial cell reaction. Alternatively, they could present an unknown autologous or exogenous antigen to T lymphocytes. T cell activation would then lead to the release of mediators of inflammation, and possibly of epidermal growth factors. This hypothesis also provides an explanation for the chronicity of psoriasis. Most of the therapies used to treat psoriasis suppress cellular immune function and inflammation. These include ultraviolet irradiation, cyclosporine, corticosteroids, methotrexate, anthralin, and retinoids.

Decreased production of interferon in whole blood cultures derived from patients with psoriasis

Patients suffering from psoriasis show many alterations with respect to their immune system as documented by in vitro test systems. In the present study we investigated the in vitro production of interferons (IFN) of leukocytes from psoriatic patients to stimulation with a variety of IFN inducers. Furthermore, the lymphoproliferative responses were tested. Whole blood cultures of 30 psoriatic patients showing moderate to severe disease activity and 21 cultures from healthy controls were stimulated with the mitogens PHA, ConA, and PWM, with PPD and Tetanus Antigen as IFN gamma inducers and with C. parvum, PolyI-PolyC, and Herpes simplex virus as inducers of IFN alpha. Interferon activity was tested in the supernatant of 48-h cultures by using an antiviral assay. Lymphoproliferation was assayed in 5-d cultures in parallel. Psoriatic patients showed a significantly decreased IFN production to all the stimuli tested. There were no significant differences in the lymphoproliferative responses; only the response to PWM was slightly decreased. The decreased IFN production by leukocytes from psoriatic patients seems to be very remarkable since increased susceptibility to infections is not generally known in these patients.

Enhanced chemiluminescence production by phagocytosing neutrophils in psoriasis

Using serum-coated zymosan, the generation of reactive oxidants by measurement of chemiluminescence was shown to be significantly enhanced in isolated peripheral psoriatic neutrophils compared to normal controls. This response was observed irrespective of whether zymosan was opsonized with fresh autologous or normal AB serum. However, this increased activity was reduced with zymosan was opsonized with serum that was preheated at 56 degrees C for 30 min. There was no statistical correlation of chemiluminescence activity with degranulation of beta-glucuronidase in either normal or psoriatic subjects. In addition, chemiluminescence produced by normal cells was significantly increased when zymosan was opsonized with psoriatic serum. The plasma membrane-bound enzyme, NAD(P)H oxidase, which produces superoxide in response to phagocytic stimulation, was significantly increased in psoriatic neutrophils compared to normal controls. These data add further evidence for activated neutrophils 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.

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.

Marked increase in the frequency of psoriatic arthritis in psoriasis patients with HLA-DR+ keratinocytes

Immunocytochemical studies with a monoclonal anti-HLA-DR antibody were performed on skin sections and keratinocyte (KTC) suspensions obtained from suction blisters of active psoriatic plaques. HLA-DR+ KTCs were found in the plaques of 23 of 38 patients with active psoriasis. Of these 23, 16 had clinical findings typical of psoriatic arthritis (PA); none of the 15 patients who lacked HLA-DR+ KTCs had PA. Although KTC HLA-DR expression was more prevalent in patients with severe skin disease, 7 of the 23 patients with HLA-DR+ KTCs in active psoriatic plaques had mild skin disease; 4 of these 7 had PA. Nail pitting or duration of skin disease did not account for increased incidence of PA in patients with HLA-DR+ KTCs. All psoriasis patients with arthritis received nonsteroidal antiinflammatory drug therapy; 14 received additional therapy directed primarily to the cutaneous manifestations of psoriasis. Nine of these noted arthritis improvement with concurrent skin response; however, in 5 patients, arthritis activity increased, despite improvement of the cutaneous disease. Two other patients, treated with methotrexate, also had concurrent skin and joint improvement. These data suggest that psoriasis patients with HLA-DR+ KTCs are at increased risk for the development of associated arthritis.

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.

Granulocyte pyruvate kinase in psoriasis vulgaris and psoriasis arthropathica

The activity of granulocyte pyruvate kinase in 46 patients with psoriasis vulgaris and eight patients with psoriasis arthropathica was investigated. It was found that in both groups of patients the activity of pyruvate kinase was significantly higher than in healthy individuals. This suggests that the rate of glycolysis in granulocytes of patients with psoriasis is markedly increased. The activity of granulocyte pyruvate kinase in 11 psoriatic patients with actively spreading lesions was compared with the activity of this enzyme when the patients were in remission. The activity of the enzyme was significantly increased during the active stage of the disease and returned to normal during remission.

Stimulation of T cells by autologous mononuclear leukocytes and epidermal cells in psoriasis

Based on reports suggesting aberrant cell-mediated immunity and altered infiltration of immunocompetent cells into the skin in psoriasis, we studied the stimulation of T cells by autologous non-T mononuclear leukocytes (autologous mixed lymphocyte reaction, AMLR) and by epidermal cells isolated from lesional and clinically uninvolved skin in psoriasis (autologous mixed epidermal cell lymphocyte reaction, AMECLR). Age- and sex-matched individuals served as controls. We found that the AMLR in psoriasis (n = 11) was similar to that in healthy controls (n = 16); furthermore, cell proliferation was alike in the presence of either 5% AB-serum or autologous serum. By contrast, while the AMECLR in healthy controls (n = 9) resembled that in psoriatics employing epidermal cells from univolved skin, epidermal cells from lesional sites (n = 10) induced a significantly higher proliferation of autologous T cells in the AMECLR (P less than 0.01). We conclude that the in vitro stimulation of T cells by non-T mononuclear leukocytes is normal in psoriasis and is not regulated by autologous serum. Lesional psoriatic epidermal cells, however, are more active in stimulating autologous T cell proliferation than cells from univolved psoriatic or normal epidermis.

Expression of HLA-DR molecules by keratinocytes, and presence of Langerhans cells in the dermal infiltrate of active psoriatic plaques

Immunoperoxidase staining of skin sections and immunofluorescence analysis of keratinocyte suspensions obtained from suction blisters of psoriatic plaques were performed using an mAb, Josh 524.4.1, and Fab'2 fragments of a rabbit antiserum, both of which are directed against nonpolymorphic determinants of HLA-DR molecules. HLA-DR+ keratinocytes were present in plaques, but not normal-appearing skin, from a significant portion of patients with active psoriasis. Double-labelling immunofluorescence experiments with either the monoclonal or polyclonal anti-HLA-DR antibody, in conjunction with the mAb OKT6, which identifies DR+ Langerhans cells, demonstrated that HLA-DR molecules were present on OKT6- keratinocytes. The dermal infiltrate of psoriatic plaques contained T cells expressing the activation antigens, IL-2 receptor (Tac) and HLA-DR, as well as macrophages and OKT6+ cells. There was little difference in the characteristics of the dermal infiltrate between the lesions with or without HLA-DR+ keratinocytes. OKT6+ presumptive Langerhans cells were also found in the dermal infiltrates of patients with lichen planus, contact dermatitis, spongiotic dermatitis, erythema multiforme, basal and squamous cell carcinoma. Studies of keratinocyte suspensions showed that 7-84% of keratinocytes were HLA-DR+. Flow cytometry experiments showed that keratinocytes at all stages of differentiation were HLA-DR+. However, the stem cell-enriched population contained the highest proportion of HLA-DR+ cells. HLA-DR expression by keratinocytes correlated with disease activity. The expression was reversible with successful medical therapy. HLA-DR+ keratinocytes may activate T cells directly or may present an as yet unknown antigen to T cells. These studies provide further support for the hypothesis that immunological mechanisms play an important role in the pathogenesis of psoriasis.

The chemokinetic response of psoriatic and normal polymorphonuclear leukocytes to arachidonic acid lipoxygenase products

Polymorphonuclear leukocytes (PMN) from ten patients with chronic stable plaque psoriasis, five of whom had more than 40% skin involvement and five with less than 20% involvement, responded in a dose-related fashion to stimulation with the arachidonic acid lipoxygenase products 5- and 12-hydroxyeicosatetraenoic acid (5- and 12-HETE) and leukotriene B4 (LTB4) in an in vitro chemokinesis assay. There was no significant difference in either the random migration or the chemokinetic response of psoriatic PMN to LTB4 when compared to the responses of PMN from a group of age- and sex-matched healthy controls. Psoriatic PMN migrated further in response to low doses of 5- and 12-HETE although the distance moved after maximal stimulation was no different to that observed in controls. No significant difference was observed in the responses of PMN obtained from patients with less than 20% skin involvement when compared to those with more extensive psoriasis. The small differences measured between the chemokinetic responses of psoriatic and control PMN to the lipoxygenase products tested are unlikely to be of pathogenetic significance.

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.

The major internal protein, p27, of a retrovirus-like particle is expressed in blood lymphocytes from psoriatic patients

Retrovirus-like particles were isolated from the urine of a patient with psoriasis. The major internal protein, p27, in these particles was isolated by immunosorbent chromatography and gel filtration on a Sephacryl S-300 column in 6 M guanidine hydrochloride. The protein was purified to homogeneity as judged by SDS-PAGE. A hyperimmune serum with specificity for p27 was obtained by vaccination of a rabbit with purified p27 antigen. This antiserum was used to examine blood lymphocytes for the expression of p27 antigen by indirect immunofluorescence. Between 0.1 and 1 per cent of the lymphocytes obtained from patients with psoriasis showed a bright cytoplasmatic (and membrane) fluorescence while no p27 positive cells could be detected in the preparations from the healthy controls (frequency less than 0.01 per cent). Among the p27 positive psoriatic cells were lymphocytes with markers for T cells, B cells and NK cells.

Coexistence of psoriasis vulgaris and bullous diseases

The coexistence of psoriasis vulgaris and bullous diseases has been described in the literature, mainly with bullous pemphigoid. In the majority of cases the bullous eruption has been thought to be related to antipsoriatic treatment. We describe nine cases of psoriasis vulgaris that were associated with bullous diseases: five bullous pemphigoid, one cicatricial pemphigoid, and three pemphigus vulgaris. The association between psoriasis vulgaris and these bullous diseases may be explained on an immunologic basis.

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.

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.

Psoriatic sera decrease responses of stimulated granulocytes from normal and psoriatic subjects

Previous studies have demonstrated alterations in polymorphonuclear leukocyte (PMNL) function in patients with psoriasis, but results have been variable. In this study we attempted to determine whether functional changes in PMNL from psoriatics represented an intrinsic cellular defect or a response to factors in serum. We evaluated the effect of the continuous presence of autologous and heterologous serum on lysozyme release and superoxide anion (O2-) generation by psoriatic and normal PMNL exposed to a soluble or particulate phagocytic stimulus. There were no differences in O2- generation or lysozyme release between normal and psoriatic PMNL without serum. However, in the presence of 10% autologous serum, these responses were significantly decreased for psoriatic PMNL (p less than .001). The results were not time-dependent and did not correlate with the extent of psoriatic involvement. The data support the hypothesis that serum factors exist in patients with psoriasis that may affect PMNL functions. The presence or absence of such factors could explain, in part, the differences between the various investigations of PMNL function in psoriasis.

Studies on the phagocytic activity of the granulocytes in psoriasis and palmoplantar pustulosis

A kinetic method was used to determine the rates of phagocytosis of IgG-coated and C3b-IgG-coated latex particles by neutrophil granulocytes from twenty patients with psoriasis and twenty with palmoplantar pustulosis (PPP). Patients with psoriasis showed a highly increased rate of uptake of IgG-coated particles. An increased rate was also observed in patients with PPP. These results indicate enhanced Fc-receptor function. In healthy controls the uptake rate of C3b-IgG-coated particles was at least 30% higher than that of particles coated with IgG alone. In nearly half of the patients in the psoriasis and PPP groups the uptake rate failed to increase in the normal way, indicating that C3b dysfunction is common in both psoriasis and PPP. In neither group was there any relationship between the rate of phagocytosis and the clinical severity of the disease.

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

Psoriatic patients, particularly those with psoriatic arthritis, have neutrophilic and eosinophilic leukocytosis. Isolated polymorphonuclear leukocytes (PMNLs) from psoriatic patients have normal concentrations of proteolytic enzymes and they have beta-adrenergic receptors of normal density and affinity. PMNLs from psoriatic patients responded normally to the synthetic chemotactic peptide, f-Met-Leu-Phe (formyl-methionine-leucine-phenylalanine). The chemotactic activities of sera from psoriatic patients were similar to those of normal sera. Sera from psoriatic patients enhanced chemokinesis of PMNLs more than normal control sera at a final concentration of 1%; no difference in chemokinetic response between psoriatic and normal sera was found at serum concentrations greater than 2.5%. This study suggests that the peripheral PMNLs from psoriatic patients are normal, but the sera of psoriatic patients has more chemokinetic activity for PMNLs than does normal serum.

Is chemotactic activity of polymorphonuclear leukocytes increased in psoriasis?

Chemotactic activity of PMNs of 44 patients with common psoriasis and 20 healthy individuals was studied by modified Boyden chamber assay and casein as a chemoattractant. The patients were classified according to the activity of the disease, extent of skin lesions, and duration of the disease and of the last relapse. There was a high statistically significant increase in chemotactic response of the PMNs of psoriatics as compared with controls. The increase in chemotactic activity correlated positively with the activity of the disease but not with the extent of skin lesions. Very low values in some patients with longlasting and/or extensive lesions could depend upon the presence of inhibitory factors in plasma. The possible explanation for divergent results obtained by other authors could be due to the fact that various clinical parameters were not taken into account.

Circulating IgA immune complexes in patients with psoriasis

The sera of 21 patients with psoriasis were examined for the presence of IgA-containing circulating immune complexes (CIC) using the Raji IgA radioimmunoassay. In addition, the Raji IgG radioimmunoassay and 125I-Clq binding assay were used to detect IgG- and IgM-containing CIC. Twenty-five patients with other hyperkeratotic skin disorders were studied as controls. Patients were studied before institution of systemic therapy with etretinate (20 patients) or 13-cis-retinoic acid (1 patient). In addition, sera of 15 of the patients treated with etretinate were studied before, during, and after therapy. The extent of pretreatment disease involvement as well as response to therapy were evaluated in a blinded fashion. Fourteen of 21 (67%) patients with psoriasis had evidence of IgA-containing CIC at some time during the course of their disease, as compared to only 1 of 25 patients with other hyperkeratotic skin disorders. In contrast, only 2 of 19 (11%) had evidence of IgG-containing CIC using the Raji IgG assay, and only 1 of 19 (5%) had evidence of IgG- or IgM-containing CIC using the 125I-Clq binding assay. A positive correlation was found between the extent of pretreatment disease involvement and the level of IgA-containing CIC by linear regression analysis (p = 0.01). There was, however, no correlation between clinical improvement and the presence or level of IgA-containing CIC in 15 patients followed during therapy. Sucrose density gradient analysis of the IgA-containing CIC found in 2 of these patients demonstrated IgA-containing CIC in the 9S to 13S region. The finding of IgA-containing CIC in a significant number of patients with psoriasis and the relative absence of IgG- or IgM-containing CIC suggest that IgA-containing CIC may play a role in psoriasis. The lack of correlation with clinical improvement, however, suggests these IgA-containing CIC are not directly related to the cutaneous manifestations of psoriasis, but may be important in the modification of immune or inflammatory responses in these patients.

Morphological and functional findings of fixed phagocytes in psoriatics

Twenty-one psoriatics as well as 24 normal healthy adults were studied by functional bone marrow scintigraphy using Tc-99m-labeled human serum albumin millimicrospheres (Tc-99m-HSA-MM). Functional bone marrow scintigraphy is an in vivo test system for the assessment of various functional properties of fixed phagocytes. Of psoriatics who had no systemic drug treatment, 59% demonstrated peripheral extension of the bone marrow space, indicating hyperplasia of bone marrow phagocytes. This phenomenon could be observed only in one normal subject who was a high-performance sportsman. Of psoriatics treated with aromatic retinoid, 83% (n = 6) demonstrated bone marrow extension, as did 100% (n = 3) of psoriatics with cirrhosis of liver. The "capacity' of bone marrow phagocytes to engulf Tc-99m-HSA-MM ("uptake ratio') was diminished in 34% of nontreated as well as 66% of psoriatics treated with aromatic retinoid. The phagocytic and proteolytic turnover of Tc-99m-HSA-MM in the bone marrow, spleen, and liver was found to e accelerated in 66% of nontreated psoriatics, normal (83%) or accelerated (17%) in psoriatics treated with aromatic retinoid, and considerably delayed in all of the psoriatics with cirrhosis of liver. Functional bone marrow scintigraphy proved to be an appropriate in vivo test system for revealing abnormalities of fixed phagocytes in psoriatics. Furthermore, therapeutic effects as well as the influences of preexisting disorders on different phagocyte populations can be assessed.

Aberrations in T-cell subpopulations in patients with psoriasis and psoriatic arthritis

Peripheral blood T-cell subpopulations and B-cell numbers from 25 patients with uncomplicated psoriasis and 22 patients with psoriatic arthritis were compared with those of 24 age- and sex-matched healthy volunteers and 11 patients with radiologically defined erosive osteoarthritis. The numbers of early and late rosettes were found to be reduced in patients with psoriasis, with and without arthritis, while the total T-cell population (measured by aminoethylthiouronium bromide-rosettes) was found to be normal. There was no difference in the number of B cells between psoriatic patients and controls. Dose-response studies of mitogen stimulation with phytohemagglutinin and concanavalin A revealed generally higher proliferative responses in the psoriatic patients only at supraoptimal concentrations. The pokeweed mitogen response, however, was reduced in patients with cutaneous psoriasis and increased in patients with psoriatic arthritis. These studies further support the concept of an immunologic imbalance in lymphocyte populations from patients with psoriasis and psoriatic arthritis.

Effects of psoriatic sera on the generation of oxygen intermediates by normal polymorphonuclear leucocytes

The effects of psoriatic sera were investigated on the generation of oxygen intermediates (OIs) by normal polymorphonuclear leucocytes (PMNs). Although increased superoxide generation was noted, a further respiratory burst of the PMns was significantly suppressed. Since superoxide dismutase (SOD) and catalase activities of the sera assayed in the xanthine-xanthine oxidase system were comparable to the controls, it still remains obscure why this dissociation occurs. It is suggested that increased generation of superoxide anion from the PMNs may be another facet of PMN activation which plays an important role in the psoriatic process.

Neutrophil chemotaxis in psoriasis before and after PUVA therapy

Chemokinesis and chemotaxis of neutrophil leucocytes were studied by migration under agarose in 35 patients with psoriasis and compared with 35 healthy controls. Eschericheae coli filtrate and lipopolysaccharide were used as chemo-attractants. Of these patients, 14 were tested before and after photochemotherapy. The chemotactic capacities of psoriatic serum before and after PUVA therapy were also investigated. The increase in the chemotactic activity of psoriatic polymorphonuclear leucocytes (PMNs) was not significant and remained unchanged after PUVA therapy. The activated psoriatic serum showed a slight increase in chemotactic activity when compared with normal activated serum. These results do not support an intrinsic abnormality of psoriatic PMNs, and their migration into psoriatic lesions could be chiefly due to the presence of chemotactic factors in involved epidermis.

Increased respiratory burst activity of monocytes and polymorphonuclear leukocytes in psoriasis

We studied the respiratory burst activity of peripheral blood monocytes and polymorphonuclear leukocytes (PMN) in eleven patients with psoriasis and eleven healthy controls, using zymosan particles to activate the phagocytes in vitro. The activation of the phagocytes was measured in a luminol-enhanced chiluminescence (CL) assay. We found a significantly higher respiratory burst activity of both monocytes and PMN in patients with psoriasis compared with the control subjects. The percentages of monocytes in psoriatics did not differ from those of the controls. The higher amount of zymosan-induced CL activity generated in the patient group was unrelated to the age of the individual. Our data indicate increased metabolic reactivity of both monocytes and PMN in psoriasis.

Neutrophil studies in psoriatics: in vivo migration, phagocytosis and bacterial killing

A reproducible method for sequential study of migration out of human skin, phagocytosis and bactericidal activity of neutrophils is described. Untreated psoriatics exhibit an early increase of chemotactic activity (0-8 hr, p less than 0.02) and subsequently a strong inhibition of chemotaxis (8-24 hr, p less than 0.01), a slight decrease of phagocytosis and a decrease in bactericidal activity (20 min, p less than 0.02; 30 min, p less than 0.003); 60 min, p less than 0.001; 120 min, p less than 0.001) as compared with controls. After clearing of skin lesions, the early increased chemotactic activity returned to normal values but the subsequent chemotactic inhibition remains as strong as before treatment. Phagocytosis increased to normal values (p less than 0.02) and bactericidal activity also increased but remained significantly low. These abnormalities were more evident in migrating than in circulating neutrophils, underlining the sensitivity of the described method.

On the mechanism of enhanced monocyte and neutrophil cytotoxicity in severe psoriasis

Monocyte and neutrophil function assessed as antibody-dependent cell-mediated cytotoxicity (ADCC) using IgG-sensitizing human erythrocytes as target cells was enhanced in patients with severe psoriasis when compared to healthy controls. We found significant correlation between increased monocyte ADCC and increased neutrophil ADCC, No differences in basal cAMP levels and cAMP responses during initiation of the ADCC reaction was observed between psoriatics and normals. Also degranulation determined as lysozyme release during ADCC was normal. In contrast, the increase in ADCC was significantly correlated to an enhanced hexose monophosphate shunt activation in the effector cells during the cytotoxic reaction. Activity of enzymes responsible for the respiratory burst was not altered in psoriasis since superoxide production after stimulation with phorbol myristate acetate was normal. Likewise, oxygen consumption and degranulation following phagocytosis of opsonized zymosan particles in neutrophils was found normal in psoriasis. Since monocytes showed increased binding of IgG-sensitized erythrocytes these data indicate that the enhanced monocyte and neutrophil ADCC is caused by an enhancement of the respiratory burst possibly induced by increased Fc receptor activity.