Atopic dermatitis in adults: evaluation of peripheral blood mononuclear cells proliferation response to Staphylococcus aureus enterotoxins A and B and analysis of interleukin-18 secretion

Background:  Atopic dermatitis (AD) is a chronic, inflammatory skin disease with a high prevalence and complex pathogenesis. The skin of AD patients is usually colonized by Staphylococcus aureus ( S. aureus ); its exotoxins may trigger or enhance the cutaneous inflammation. Several mediators are related to the AD immune imbalance and interleukin-18 (IL-18), an inflammatory cytokine, may play a role in the atopic skin inflammation.
Aims:  To evaluate peripheral blood mononuclear cells (PBMC) proliferation response to staphylococcal enterotoxins A (SEA) and B (SEB) and the levels of IL-18 in adults with AD.
Methods:  Thirty-eight adult patients with AD and 33 healthy controls were analysed. PBMC were stimulated with SEA and SEB, phytohemaglutinin (PHA), pokeweed (PWM), tetanus toxoid (TT) and Candida albicans (CMA). IL-18 secretion from PBMC culture supernatants and sera were measured by ELISA.
Results:  A significant inhibition of the PBMC proliferation response to SEA, PHA, TT and CMA of AD patients was detected ( P  ≤ 0.05). Furthermore, increased levels of IL-18 were detected both in sera and non-stimulated PBMC culture supernatants from AD patients ( P  ≤ 0.05).
Conclusions:  A decreased PBMC proliferation response to distinct antigens and mitogens (TT, CMA, SEA and PHA) in adults with AD suggest a compromised immune profile. IL-18 secretion from AD upon stimulation was similar from controls, which may indicate a diverse mechanism of skin inflammation maintained by Staphylococcus aureus. On the other hand, augmented IL-18 secretion from AD sera and non-stimulated cell culture may enhance the immune dysfunction observed in AD, leading to constant skin inflammation.     

Age-related differences in sensitivity of peripheral blood monocytes to lipopolysaccharide and Staphylococcus aureus toxin B in atopic dermatitis

As shown by atopy patch tests, atopic dermatitis (AD) is dominated in its acute phase by the development of a specific T(H)2 response after exposure of the skin to common environmental antigens. Relying on our previous data showing that Staphylococcus aureus enterotoxin B (SEB) induced the activation of monocyte-derived dendritic cells (DCs) through Toll-like receptor (TLR)2 and that SEB-pulsed DCs commit allogenic naive T cells into T(H)2, we assessed monocytes sensitivity to SEB and lipopolysaccharide (LPS) in a group of children and adult patients with AD. Monocytes from AD patients (15 adults with mostly severe disease and 15 children with mild to moderate disease) exhibited an activated and tolerant state as supported by (i) secretion of large amounts of IL-6, IL-10, and tumor necrosis factor-alpha even in the absence of stimulation; (ii) their inability to modulate neither HLA-DR and CD54 nor TLR2 and TLR4 expression after in vitro challenge with SEB; (iii) inhibition of IL-12p70 secretion in response to LPS. Interestingly, monocytes from some of the children studied responded to in vitro challenge with LPS, suggesting new hypotheses to explain disease regression. Our data support the notion that monitoring sensitivity of monocytes to bacterial toxins could prove useful to assess disease progression and prognosis in AD.     

Enhanced IL-4 production and IL-4 receptor expression in atopic dermatitis and their modulation by interferon-gamma.

The in vivo and in vitro immunomodulatory effects of interferon gamma (IFN-gamma) treatment on peripheral blood mononuclear cells (PBMC) from patients with atopic dermatitis (AD) and elevated IgE levels were studied. As part of a double-blind placebo-controlled clinical trial, 14 AD patients were treated with IFN-gamma (n = 7) or saline (n = 7) for 12 weeks. To assess the in vivo effects of IFN-gamma treatment on interleukin (IL)-4-dependent lymphocyte function, we assessed the proliferation of AD PBMC in response to IL-4. Prior to IFN-gamma treatment, AD PBMC had proportionately decreased proliferative responses to IL-4 when compared to IL-2. After 12 weeks of in vivo treatment with IFN-gamma, there was an increase of IL-4- but not IL-2-induced lymphocyte proliferation in seven of eight AD patients. To further study the immunologic basis of these observations, we studied the expression of IL-4 receptor (IL-4R) mRNA and the production of IL-4 by PBMC from AD patients. PBMC from AD patients expressed higher levels of IL-4R mRNA and produced significantly higher amounts of IL-4 than normal controls (p less than 0.05). More importantly, the in vitro addition of IFN-gamma caused significant reduction in both IL-4R and mRNA expression and IL-4 production of PBMC from AD and non-atopic controls. These data indicate that AD is characterized by an in vivo overstimulation of the IL-4-IL-4R pathway. The poor proliferative responses of untreated AD PBMC to exogenous IL-4 may be due to increased levels of endogenous IL-4 production with constant occupancy on the IL-4R. Furthermore, in vivo and in vitro treatment with IFN-gamma down-regulates this pathway.     

Cutaneous late phase reaction in adult atopic dermatitis patients with high serum IgE antibody to Dermatophagoides farinae: correlation with IL-5 production by allergen-stimulated peripheral blood mononuclear cells

It is known that, in patients of allergic asthma and rhinitis, the late-phase reaction (LPR) occurs 6-12 h after allergen challenge, but there are few reports concerning cytokine production in the cutaneous LPR in atopic dermatitis (AD). We report here the results of our study on the relationship between the cutaneous LPR and the production of cytokines such as IL-4, IL-5, IL-2 and IFN-gamma by peripheral blood mononuclear cells (PBMC) of AD patients. We selected 29 pure AD patients with no history of atopic airway diseases who showed high serum IgE antibody against Dermatophagoides farinae and performed skin prick testing with three different antigens and observed the resultant cutaneous reactions in 23 of the AD patients. Furthermore, we measured the cytokine production by the cultured PBMC under the stimulation of the antigens and compared it with the results of the skin tests. 13 (57%) of these 23 AD patients demonstrated positive LPR in response to D. farinae, and the mean concentration of IL-5 produced by PBMC was higher in these LPR-positive AD patients compared to the LPR-negative ones. Additionally, we noticed that there was a positive correlation between the mean diameter of the erythema of LPR and the level of IL-5 production by PBMC in the LPR-positive patients. We suggest that there are at least two groups in AD patients, i.e. LPR-positive and LPR-negative ones. The observation of LPR can be an important and practical way to classify AD patients into subgroups, which may enable us to regard IL-5 or eosinophils as a target for treatment.     

Aberrant cytokine production by Sezary syndrome patients: cytokine secretion pattern resembles murine Th2 cells.

Sezary syndrome (SzS), the leukemic stage of cutaneous T-cell lymphoma (CTCL), is typically a CD4+ T-cell lympho-proliferative disease characterized by numerous immunologic abnormalities, including decreased T-cell responses to antigens and mitogens, decreased natural killer and lymphocyte-activated killer cell activities, eosinophilia, and increased levels of immunoglobulins, particularly IgE and IgA. Because this constellation of abnormalities is reminiscent of the pleiotropic in vitro activities of IL-4 and IL-5, we examined the possibility that malignant T cells in SzS may be producing increased amounts of IL-4 with a concomitant decrease in IL-2 and IFN-gamma production. Such a cytokine secretion pattern would be similar to that produced by murine Th2 cells. Serum IL-4 enzyme-linked immunosorbent assay measurements revealed that 33% of SzS patients (n = 21) had levels of IL-4 significantly higher (mean, 7.2 pg/ml; range, 0-48, p less than 0.05) than normal controls (mean, 1.59; range, 0-3.1). Although the majority of tested patients had elevated serum IgE, no direct correlation between serum IL-4 levels and serum IgE levels was observed. Peripheral blood mononuclear cells (PBMC) isolated from SzS patients and stimulated with phytohemagglutinin (PHA) produced significantly higher levels of interleukin (IL)-4 and significantly lower levels of IL-2 and interferon (IFN)-gamma than did PBMC from normal controls (p less than 0.02, p less than 0.05, and p less than 0.02, respectively). PBMC from SzS patients in remission produced IL-4 and IL-2 levels similar to that of the normal controls. To determine if IFN-gamma could inhibit the increased IL-4 production by PHA-stimulated PBMC from SzS patients, IFN-gamma was added to culture at 0, 24, or 48 h prior to the addition of PHA. Significant decreases in IL-4 production were seen only in cultures incubated with IFN-gamma for 24 and 48 h prior to the addition of PHA. IL-2 levels were not affected by IFN-gamma incubation. The increased IL-4 and decreased IL-2 and IFN-gamma production by PBMC from SzS patients suggests that Sezary cells have a cytokine profile similar to murine Th2 cells. Moreover, this cytokine secretion pattern may play an integral role in the immunopathogenesis of advanced CTCL. The results also suggest that IFN-gamma be a useful component in the spectrum of therapeutic approaches to SzS.     

Production of IL-4, IL-2, IFN-gamma, and TNF-alpha by peripheral blood mononuclear cells of patients with atopic dermatitis.

Recently, T cell-derived cytokines have been postulated to be involved in the pathogenesis of atopic dermatitis (AD) since the synthesis of IgE is profoundly regulated by cytokines such as IL-4, IFN-gamma and IL-2. IL-4 enhances the production of IgE and in contrast, IFN-gamma inhibits this IL-4-mediated IgE production. IL-2 also prevents IL-4-induced production of IgE by a different mechanism from IFN-gamma, suggesting that the level of IgE is regulated by the quantitative balance of these antagonizing cytokines. We examined the production of IL-4, IL-2, IFN-gamma and TNF-alpha by PBMC of AD patients and non-AD controls. Although the production of IL-2 and TNF-alpha by AD patients was significantly lower than that of non-AD controls, the production of IL-4 and IFN-gamma did not show significant differences between AD and non-AD individuals. There was no significant correlation between cytokine production and clinical symptoms in AD patients. There was significant positive correlation between IL-4 and IL-2 production, and between IFN-gamma and TNF-alpha production. Serum IL-4 levels showed no significant difference between AD group and non-AD group.     

Cytokine release from cultured peripheral blood mononuclear cells of patients with severe atopic dermatitis

Peripheral blood mononuclear cells (PBMC) from 14 patients with severe atopic dermatitis (AD) and 11 healthy donors were tested for their capacity to produce tumour necrosis factor-alpha (TNF-alpha) after PHA stimulation and compared with their in vitro production of interferon-gamma (IFN-gamma). The mean TNF-alpha production in AD patients did not differ vis-à-vis controls. However, a significant portion of patients with AD which was defective in generating IFN-gamma in vitro showed in addition significantly a decreased production of TNF-alpha. No correlation could be found between TNF-alpha and neopterin production in either group, whereas there was a close overall correlation between the amount of TNF-alpha and IFN-gamma detectable in culture supernatants of patients and controls. Furthermore, a significant correlation was found between TNF-alpha and IFN-gamma generation in vitro and serum IgE concentration in AD. Based on cytokine production in vitro and IgE concentration in vivo, patients with severe AD could be divided into two groups. Furthermore, 3 AD patients with normal IFN-gamma generation and low serum IgE concentration but suffering from eczema herpeticum formed a subgroup which showed an increased TNF-alpha production in vitro. The data suggest alterations in cytokine production in a subgroup of patients with AD which bear a reciprocal relationship to abnormal IgE regulation.     

儿童特应性皮炎患者外周血单一核细胞IL-31与疾病严重程度相关性分析

目的 探讨IL-31在儿童特应性皮炎发病机制中的作用以及与特应性皮炎瘙痒的相关性。方法 22例特应性皮炎患儿与22例健康儿童外周血单一核细胞在葡萄球菌肠毒素B（SEB）刺激或非刺激状态下，应用实时PCR方法分析IL-31表达情况；酶联免疫吸附法测定其血清IgE水平；对患儿病情进行病情严重程度评分，分析IL-31 mRNA与IgE水平、疾病严重程度及瘙痒的相关性。结果 特应性皮炎患儿外周血单一核细胞IL-31表达显著增加，是对照组的23.2倍（P < 0.01）。特应性皮炎组和对照组外周血单一核细胞受SEB刺激后IL-31表达均有不同程度升高，以特应性皮炎组IL-31表达增加更显著，是对照组的20.44倍。患儿血清总IgE水平中位数为260.05 IU/mL（范围5.9 ～ 1131.01 IU/mL），对照组为17.7 IU/mL（范围5 ～ 140.7 IU/mL），两组比较，P < 0.01。IL-31与患儿病情严重程度以及血清总IgE水平无显著相关性（r = 0.07，P > 0.05；r = 0.22，P > 0.05）。结论 IL-31可能参与儿童特应性皮炎发病，其作用机制可能不依赖血清IgE；SEB能诱导正常人外周血单一核细胞快速表达IL-31，是IL-31产生的重要调节因素。     

T cell epitope-specific defects in the immune response to cat allergen in patients with atopic dermatitis

Atopic dermatitis (AD) is often associated with high titer IgE antibodies (ab) to allergens, and IL-10-mediated regulation of IFN-gamma has been proposed to contribute to this IgE ab production. However, the relevance of IL-10 and IFN-gamma to IgE associated with AD has not been examined in the context of an allergen-specific system. Analysis of PBMC responses in vitro showed deficient T cell proliferation to overlapping IL-10- (peptide (P) 2:1) and IFN-gamma- (P2:2) inducing chain 2 major epitopes of cat allergen (Fel d 1) in cultures from sensitized AD patients (mean IgE to cat=20.9 IU/ml). Diminished IFN-gamma induction by Fel d 1 and P2:2, along with elevated peptide-induced IL-10 (except for P2:1) was observed in PBMC cultures from AD subjects compared with non-AD (sensitized and non-sensitized) subjects. Neither T cell proliferation nor IFN-gamma production to chain 2 epitopes could be restored by anti-IL-10 mAb in cultures from sensitized AD subjects. Moreover, allergen avoidance was associated with a paradoxical decrease in both IL-10 and IFN-gamma in peptide-stimulated PBMC from these subjects. Control of IFN-gamma production to chain 2 epitopes by IL-10 may be relevant to sensitization status. Development of high titer IgE ab in AD could reflect a failure of this mechanism.     

The prevalence of antibody responses against Staphylococcus aureus antigens in patients with atopic dermatitis: a systematic review and meta‐analysis

Atopic dermatitis (AD) is a common type of eczema. The bacterium Staphylococcus (S.) aureus plays a role in AD, possibly via various substances that are part of the bacterium. In people with AD, how the body's immune system reacts to these substances might lead to the inflammation seen in AD. In this study, we provide an overview of what is known from current literature (e.g. studies published in medical journals) on the immune response (antibodies) against S. aureus substances (antigens) in AD patients compared to healthy controls (people without AD). Scientific literature was systematically obtained from different databases. We extracted data on how often (so‐called ‘prevalence’) antibodies of, among others, the IgE type directed against S. aureus can be found in AD patients. A weighted prevalence was calculated, as studies with more patients were regarded more relevant, and prevalence was compared between AD patients and healthy controls. Tests for differences between studies and overall study quality were done to interpret the robustness of the results. We included 26 publications with a total of 2369 patients. In 10 studies a control group (of people without AD) was also studied. Study quality was fair to poor. The weighted prevalence of IgE against S. aureus antigens was 33% for staphylococcal enterotoxin (SE) A, 35% for SEB and 16% for toxic shock syndrome toxin (TSST)‐1. Compared to healthy controls, AD patients had 8.37 times more IgE against SEA and 9.37 times more IgE against SEB. No significant difference was seen for IgE against TSST‐1. Interpretation of the results should take into account that there were some important differences in study design and the fact that the studies were generally small. In conclusion, AD patients more often show an IgE antibody response against the S. aureus antigens SEA and SEB compared to healthy controls. These findings show that S. aureus may have a role in AD.     

Beneficial effects of fumarate therapy in psoriasis vulgaris patients coincide with downregulation of type 1 cytokines

BACKGROUND: Fumarates have been shown to be effective in psoriasis vulgaris. OBJECTIVES: To find out whether successful therapy is associated with modulation of cytokines. METHODS: We determined interferon (IFN)-gamma, interleukin (IL)-4 and IL-10 secretion capacities of peripheral blood mononuclear cells (PBMC) after phytohaemagglutinin stimulation, and IL-12p70 and IL-10 secretion capacities of PBMC after endotoxin stimulation in psoriasis vulgaris patients during treatment with fumarates. In a cohort study, 12 patients (five men, median age 50 years; seven women, median age 46 years) with psoriasis vulgaris were followed during 24 months of fumarate treatment. In addition, we followed 14 healthy controls (six men, median age 31 years; eight women, median age 29 years) without skin diseases during 12 months to investigate possible changes in the cytokine secretion capacity of PBMC as a result of seasonal changes. Disease activity in patients was determined by Psoriasis Area and Severity Index (PASI) score. Blood was collected for measurement by enzyme-linked immunosorbent assay of cytokine levels after stimulation of PBMC. RESULTS: Within 6 months of fumarate treatment, the mean +/- SD PASI score had decreased to 22 +/- 9% of its initial value. These beneficial effects coincided with lymphocytopenia and a significant (P < 0.05) downregulation of IFN-gamma expression by circulating blood cells, followed by a significant downregulation of IL-4 expression. Notably, production of the cytokine synthesis inhibitor IL-10 by PBMC was unchanged. CONCLUSIONS: The beneficial effects of fumarates may be attributed to their downregulatory action on type 1 cytokines.     

The modulation of cytokine and IgE production by tumor necrosis factor-beta in atopic dermatitis

Atopic dermatitis (AD) is associated with increased IL-4, IL-5, and IL-13 but decreased IFN-gamma production. This cytokine profile may account for the atopic features of this illness, including IgE upregulation. Recent studies have demonstrated that tumor necrosis factor (TNF)-beta is produced by Th1-like cells, but the cytokine modulation by TNF-beta and the clinical significance of this cytokine in AD is not known. Therefore, this study was carried out to determine the potential role of TNF-beta in AD. In this study, we cultured peripheral blood mononuclear cells from patients with AD and normal subjects with anti-CD3 monoclonal antibodies and investigated the production of TNF-beta by ELISA. The mean +/- SEM of TNF-beta production in AD was significantly lower than normal subjects (p = 0.03). The effect of TNF-beta on cytokine production was investigated by culturing peripheral blood mononuclear cells with anti-CD3 monoclonal antibodies in the presence or absence of TNF-beta. Compared with medium control, TNF-beta significantly decreased IL-5 (p = 0.0004) and IL-13 (p = 0.008) but increased IFN-gamma (p = 0.001) production. The effect of TNF-beta on IgE production was determined by culturing peripheral blood mononuclear cells in the IL-4- and anti-CD40-induced IgE production system. Interestingly, TNF-beta significantly decreased IgE (p = 0.02), but not IgG production compared with medium control. Our study demonstrates that TNF-beta production is downregulated in AD. This cytokine increases IFN-gamma production but decreases IL-5, IL-13, as well as IgE production. These findings suggest a potential role for TNF-beta in the pathogenesis of AD.     

The importance of CD54 and CD86 costimulation in T cells stimulated with Candida albicans and Dermatophagoides farinae antigens in patients with atopic dermatitis

Abstract A number of studies have demonstrated an increased frequency of allergen-specific T cells producing increased amounts of interleukin-4 (IL-4) and IL-5, but little interferon-γ in both the peripheral blood and skin lesions of patients with atopic dermatitis (AD). In this study, to further clarify the characteristics of T cells obtained from AD patients, we examined the dependency of the antigen-specific proliferation of peripheral blood mononuclear cells (PBMC) from AD patients on costimulatory molecules. The antigens used were Candida albicans and Dermatophagoides farinae, for which AD patients show increased levels of IgE antibodies. PBMC from control healthy donors stimulated with these antigens incorporated [³H]-thymidine much more than PBMC from AD patients. The addition of anti-CD54, -CD40, -CD80 and -CD86 monoclonal antibodies to the cultures showed that the PBMC required only CD54 and CD86 for stimulation with C. albicans, but required CD54, CD80 and CD86 for stimulation with D. farinae. Among these monoclonal antibodies, the anti-CD54 antibody suppressed the proliferative responses of most PBMC, most effectively followed by the anti-CD86 antibody. However, there were no significant differences in the requirement for costimulatory molecules of PBMC proliferation stimulated with C. albicans or D. farinae between AD patients and healthy donors. Since many studies have suggested that T-helper type 1 and T-helper type 2 immune responses are different in their dependency on CD80 or CD86 costimulation, our present results suggest that the allergen-specific T cells of AD patients are not completely shifted to a T-helper type 2 subset. Received: 10 February 1998 / Received after revision: 2 July 1998 / Accepted: 2 July 1998     

Effects of recombinant human soluble interleukin-4 receptor on interleukin-4/staphylococcal enterotoxin B-stimulated peripheral mononuclear cells from patients with atopic eczema

In atopic eczema both in local inflammatory reactions and in peripheral blood high interleukin (IL) 4: interferon-γ (IFN-γ) production ratios have been demonstrated, indicating predominance of TH₂ cell subsets resulting in increased IL-4 production and high serum IgE. The in vitro immunomodulatory effects of recombinant human soluble IL-4 receptor (rsIL-4R) on IL-4-stimulated lymphocyte proliferation, IgE and IFN-γ production were studied in peripheral blood mononuclear cells from 10 patients with atopic eczema and seven healthy donors. In addition to control cultures (without any stimulus) and cultures with simultaneous application of rsIL-4R and IL-4, time-kinetic experiments were performed. We further investigated the influence of rsIL-4R on IL-4 production in staphylococcal enterotoxin B (SEB) stimulated peripheral blood mononuclear cells. Early addition of rsIL-4R to IL-4-stimulated peripheral blood mononuclear cells resulted in an increase in IFN-γ production and in suppression of IL-4 induced proliferation and IgE secretion. Unexpectedly, rsIL-4R in combination with SEB exhibited an IL-4 protective effect with a significant increase in detectable IL-4 in the culture supernatants. The present data support the assumption that rsIL-4R might be a promising new immunomodulatory substance in the treatment of atopic eczema.     

Phenotypic analysis of CD23+ peripheral blood mononuclear cells in atopic dermatitis

There is an increase in the number of CD23+ cells in peripheral blood mononuclear cells (PBMC) in atopic dermatitis (AD). We analysed the subpopulation of CD23+ PBMC in 11 patients with AD and in 10 healthy controls and found that B cells (CD20+) and non-T, non-B cells (CD3- CD20-) (mainly monocytes) were responsible for the elevation of CD23+ cells. CD23+ T cells (CD3+) comprised only 4.6% of total CD23+ cells in AD. The percentage of CD23+ cells did not correlate with the serum log IgE level nor with clinical severity of AD. Interleukin 4 (IL-4) induced the expression of CD23 antigen in PBMC both in AD and in healthy controls in a dose-dependent manner in vitro. This enhancing effect of IL-4 was completely abrogated by the addition of anti-IL-4 monoclonal antibody. Other cytokines such as IL-1, IL-2, IL-3, IFN-alpha, IFN-gamma and TNF-alpha had no significant effects on CD23 expression.     

Synergistic effects of interleukin 4 and interferon-gamma on monocyte phosphodiesterase activity.

Patients with atopic dermatitis (AD) have elevated leukocyte cyclic AMP-phosphodiesterase (PDE) activity and increased in vitro IgE synthesis compared to normal (NL) subjects. Interleukin 4 (IL-4), interferon-gamma (IFN-gamma), and PDE inhibitor have been shown to regulate in vitro IgE synthesis. This study investigated whether soluble T-cell factors such as IL-4 and IFN-gamma could account for elevated PDE activity in patients with AD. Both rhIL-4 and IFN-gamma significantly increased normal monocyte PDE activity to a maximum of 188% (n = 6, p less than 0.05) and 315% above control (n = 3, p less than 0.05), respectively. At concentrations below 0.1 units/ml IL-4 and IFN-gamma had synergistic effects on activation of monocyte PDE. AD and NL T-cell culture supernatants also significantly stimulated normal monocyte PDE activity, but the stimulatory activity was not significantly greater in the AD T-cell supernatants. The effect of both cytokines and T-cell supernatants on normal monocytes was inhibited by antibodies against IL-4 and IFN-gamma, respectively. This study demonstrates that IL-4 and IFN-gamma can increase PDE activity in normal monocytes. Though the levels of IL-4 and IFN-gamma in T-cell supernatants are undetectable with an enzyme-linked immunosorbent assay (ELISA) assay, the concentration of these cytokines below the detectable level can significantly increase PDE activity of monocytes in a synergistic and dose-dependent manner. These results suggest that cytokine-mediated activation of monocytes can increase PDE activity. Furthermore, lymphokines may play an important role in modulating the cyclic nucleotide regulatory pathway.     

Impaired responses of peripheral blood mononuclear cells to nickel in patients with nickel-allergic contact dermatitis and concomitant atopic dermatitis

BACKGROUND: Allergic contact dermatitis (ACD) is pathogenetically dependent on cell-mediated immune responses mediated by type 1 T lymphocytes. Atopic dermatitis (AD), in contrast, occurs as a result of sustained activation of type 2 subsets of T cells. Although atopic patients may become sensitized to various contact allergens, little is known about the influence of atopy on delayed-type hypersensitivity. OBJECTIVES: To investigate the in vitro responses of peripheral blood mononuclear cells (PBMC) to nickel stimulation in groups of atopic and nonatopic patients with patch test-verified nickel ACD. METHODS: Ten nonatopic patients with nickel ACD, 10 patients with nickel ACD and concomitant AD, 10 patients with AD but with no contact allergy, and 10 healthy persons participated in the study. PBMC were cultured in the presence or absence of nickel sulphate, phytohaemagglutinin (PHA) or tetanus toxoid (TT). [(3)H]thymidine incorporation was used to measure the rate of antigen-induced DNA synthesis and enzyme-linked immunosorbent assay was used to measure the production of interleukin (IL)-2 (type 1 cytokine) and IL-5 (type 2 cytokine). RESULTS: Nickel-stimulated PBMC of nickel-allergic patients with AD proliferated significantly less and secreted significantly lower amounts of IL-2 than cells of nonatopic nickel-allergic patients. IL-5 production was also lower in the former group, although the difference was nonsignificant. Moreover, neither the nickel-specific DNA synthesis nor the cytokine production by PBMC of atopic nickel-allergic patients differed significantly from those of healthy control persons and AD patients without contact allergy. Proliferative and secretory responses of PBMC to PHA or TT stimulation differed nonsignificantly between the groups. Nickel-induced IL-2 production correlated well with IL-5 production in nickel-allergic patients regardless of their atopic status. CONCLUSIONS: Our results indicate that PBMC of nickel-allergic patients with concomitant AD are characterized by impaired in vitro proliferative and secretory responses to the contact allergen nickel but not to the mitogen PHA or the recall antigen TT. The type 2 cytokine IL-5 may play a role in the development of ACD.     

Alteration in the production of IL-10 and IL-12 and aberrant expression of CD23, CD83 and CD86 by monocytes or monocyte-derived dendritic cells from atopic dermatitis patients

Atopic dermatitis (AD) is characterized by the presence of Th2-type cells in the skin infiltration as well as in the peripheral blood, although a predominant infiltration of interferon-gamma (IFN-gamma)-producing cells is also reported in the chronic skin lesions of AD. Recently it has become clear that the development of Th1 or Th2 is strongly influenced by factors produced by the antigen presenting cells (APCs). To clarify whether APCs from AD patients play a favorable role in the differentiation of Th2 cells, we compared the production of cytokines and the expression of co-stimulatory molecules by monocytes (MOs) and monocyte-derived DCs (MoDCs) after stimulations with various reagents between 13 AD patients and 13 age-matched healthy controls. We examined their production of IL-1 beta, IL-10, IL-12p40, and IL-12p70, and their expression of CD23, CD40, CD54, CD80, CD83, CD86 and HLA-DR. We stimulated them with superantigens, lipopolysaccharide (LPS), agonistic anti-CD40 antibody, phytohemagglutinins (PHA), IL-1beta/TNF-alpha, IL-4, or IFN-gamma. The following results were obtained (1): IL-10 production was significantly enhanced in AD MOs after LPS stimulation. In contrast, IL-12p40 production was significantly lower in AD MOs than in HC MOs after a variety of stimulations (2). IL-12p40 was also significantly lower in AD MoDCs after LPS stimulation (3). The induction of CD23 with IL-4 was significantly higher in AD MOs. and finally (4), AD MoDCs augmented the expression of CD83, CD86, and HLA-DR less significantly than HC MoDCs after anti-CD40 Ab stimulation. These data indicate that AD APCs show some responses different from those observed in HC APCs after several stimulations, such as LPS, IL-1 beta/TNF-alpha, IL-4, or anti-CD40 Ab, and that these responses might play a role in the polarizing process of helper T cells into Th2 cells as recognized in AD patients.