Outcome of Referrals for Non-Responsive Celiac Disease in a Tertiary Center: Low Incidence of Refractory Celiac Disease in the Netherlands.

OBJECTIVES: Refractory celiac disease (RCD) is a severe cause of non-responsive celiac disease (CD) due to its association with the enteropathy associated T-cell lymphoma (EATL). Conflicting data exist on the prevalence and the clinical manifestations of RCD type I (RCD I) and type II (RCD II). The aim of the current study was to provide insight in the incidence of RCD and in the distinction with other causes of non-responsive CD. METHODS: A total of 106 CD patients were referred to our tertiary referral center between January 2006 and December 2011 for evaluation of non-responsive CD. In addition, a questionnaire was sent to all 82 gastroenterology departments in the Netherlands to reveal whether a patient with RCD was currently being evaluated or had been treated between 2006 and 2012. RESULTS: During a 6 year period, a total of 31 patients were diagnosed with RCD (19 RCD I and 12 RCD II). The nationwide survey revealed 5 additional patients with RCD I and one patient with RCD II. This leads to an annual incidence of RCD of 0.83/10.000 CD patients. The remaining patients were diagnosed with involuntary gluten ingestion (21.7%), delayed mucosal recovery (11.3%), enteropathy associated T-cell lymphoma (7.5%) and autoimmune enteropathy (1.8%). CONCLUSIONS: This nationwide study reveals a low incidence of RCD in the Netherlands. Nevertheless, RCD is a clinically relevant disease entity in CD patients non-responsive to the gluten-free diet.

Innate stimulatory capacity of high molecular weight transition metals Au (gold) and Hg (mercury).

Nickel, cobalt and palladium ions can induce an innate immune response by triggering Toll-like receptor (TLR)-4 which is present on dendritic cells (DC). Here we studied mechanisms of action for DC immunotoxicity to gold and mercury. Next to gold (Na3Au (S2O3)2⋅2H2O) and mercury (HgCl2), nickel (NiCl2) was included as a positive control. MoDC activation was assessed by release of the pro-inflammatory mediator IL-8. Also PBMC were studied, and THP-1 cells were used as a substitution for DC for evaluation of cytokines and chemokines, as well as phenotypic, alterations in response to gold and mercury. Our results showed that both Na3Au (S2O3)2⋅2H2O and HgCl2 induce substantial release of IL-8, but not IL-6, CCL2 or IL-10, from MoDc, PBMC, or THP-1 cells. Also gold and, to a lesser extent mercury, caused modest dendritic cell maturation as detected by increased membrane expression of CD40 and CD80. Both metals thus show innate immune response capacities, although to a lower extent than reported earlier for NiCl2, CoCl2 and Na2 [PdCl4]. Importantly, the gold-induced response could be ascribed to TLR3 rather than TLR4 triggering, whereas the nature of the innate mercury response remains to be clarified. In conclusion both gold and mercury can induce innate immune responses, which for gold could be ascribed to TLR3 dependent signalling. These responses are likely to contribute to adaptive immune responses to these metals, as reflected by skin and mucosal allergies.

Optimal strategies to identify aberrant intra-epithelial lymphocytes in refractory coeliac disease.

INTRODUCTION: Different strategies have been developed to identify those refractory celiac disease (RCD) patients who are at risk to develop an enteropathy associated T-cell lymphoma (EATL). Flow cytometric analysis of intra-epithelial lymphocytes (IEL) with an aberrant phenotype is considered the golden standard but is not widely available. Immunohistochemistry (IHC) and T-cell receptor (TCR) rearrangement studies are commonly available but may lack sensitivity and specificity. Here, we compared the three different methods in the workup of patients suspected for RCD. METHODS: Duodenal biopsies from control patient (n = 5), RCD patients with moderately increased aberrant IEL populations (20-50 %: n = 14), and RCD patients with high numbers of aberrant IEL (>50 %: n = 5) as determined by flow cytometry were analysed by IHC and TCR-γ chain rearrangement analysis. Three pathologists scored the slides independently. RESULTS: Sensitivity of IHC and TCR-γ rearrangement analysis in RCD patients with high numbers of aberrant IELs was 100 and 71 %, respectively. RCD patients with aberrant cells between 25 and 50 % however, were missed by IHC and TCR in 50 and 57 % of cases, respectively. In addition, inter-rater reliability analysis of the IHC scoring revealed coder-pair Kappa coefficients between 0.28 and 0.85. CONCLUSION: Immunohistochemistry and to a lesser extent TCR-γ clonality analysis are sensitive in identifying patients with high numbers of aberrant IEL populations, yet miss half of RCD patients with moderately increased numbers. In addition, IHC has a high inter-observer variability. Therefore, patients suspected for RCD should undergo flow cytometric analysis of the duodenum.

Serum autoantibodies directed against transglutaminase-2 have a low avidity compared with alloantibodies against gliadin in coeliac disease.

Coeliac disease is characterized by intolerance to gliadin and related gluten components present in wheat, barley and rye. Coeliac disease patients harbour antibodies directed against alloantigens such as gliadin, but also against the autoantigen transglutaminase-2 (TG2). The type and quality of antibody responses provides insight into the underlying immune activation processes. Therefore, in this study we have analysed the avidity of the antibody response directed against the autoantigen TG2 and compared this with antibody responses against the alloantigens gliadin and Escherichia coli. We observed that the immunoglobulin (Ig)A autoantibody response directed against TG2 is of low avidity compared with the IgA response against the alloantigens gliadin and E. coli in the same patients; the same was true for IgG, both in IgA-deficient and in -sufficient coeliac patients. The observed avidities appear not to be related to disease stage, antibody levels, age or duration of exposure to gluten. In conclusion, in coeliac disease there is a clear difference in avidity of the antibody responses directed against the auto- and alloantigens, indicating different regulation or site of initiation of these responses.

Effector memory T-cell frequencies in relation to tumour stage, location and HPV status in HNSCC patients.

BACKGROUND: The immune system plays an important role in tumour immune surveillance. Head and neck squamous cell carcinoma patients are often immune compromised. OBJECTIVE: To chart the baseline levels of T-cell subpopulation frequencies in patients with cancer prior to treatment. SUBJECTS AND METHODS: Blood samples of patients were taken at the time of diagnosis, analysed with flowcytometry and compared with blood samples of healthy donors. RESULTS: Compared to healthy donors, a significant shift from naive to effector memory T cells was observed. This effect was most prominent in stage II patients. A similar shift from naive to effector memory T cells was noted in patients with oropharynx or larynx squamous cell carcinomas. Furthermore, the percentage of effector memory and effector T cells was higher in the group of patients with human papillomavirus-positive oropharyngeal squamous cell carcinomas, compared with patients with human papillomavirus-negative tumours, suggestive of virus-induced T-cell activation. CONCLUSION: Here, we provide a simple and easily implementable tool to document T lymphocyte subsets in the peripheral blood of head and neck cancer patients, which might be useful for prognosis and/or therapy response prediction.

Palladium-induced Th2 cytokine responses reflect skin test reactivity.

Recently, a crucial role of Th2 responses in nickel allergic contact dermatitis (ACD) was demonstrated. As palladium allergy is an issue of growing interest, the diagnostic potential of Th2 parameters for palladium sensitization was investigated. Palladium (Na(2) [PdCl(4)])-induced lymphocyte proliferation (LPT), Th1 and Th2 cytokine production were correlated with skin test (ST) reactivity in 16 positive and 21 negative controls. Furthermore, the diagnostic potential of these assays was evaluated using receiver operating characteristics (ROC) analysis. For comparison, same experiments were carried out for nickel (NiSO(4)). Correlation coefficients between palladium ST reactivity and IFN-γ, LPT, IL-5, and IL-13 were 0.34, 0.51, 0.69, and 0.78, and overall test accuracies were 68%, 81%, 89%, and 95%, respectively. Both palladium- and nickel-mediated Th2 responses tightly correlate with ST reactivity, supporting recent findings on the crucial role of Th2 involvement in ACD. Therefore, these assays may have great potential as diagnostic tools for future in vitro sensitization testing.

Gluten-dependent antibodies in horses with inflammatory small bowel disease (ISBD).

BACKGROUND: Equine inflammatory small bowel disease (ISBD) is an idiopathic pathologic condition seeming to increase in prevalence. OBJECTIVE: To investigate the potential role of gluten in equine ISBD. ANIMALS & METHODS: Antibodies known to be important in the diagnosis of human coeliac disease (CD): IgA antibodies to human recombinant and guinea pig tissue-transglutaminase (TGA), native gliadin (AGA), deamidated-gliadin-peptides (DGPA), and primate and equine endomysium (EMA) were assessed in blood samples from three different groups of horses: ISBD affected (n = 12) on a gluten-rich diet and controls either on gluten-rich (n = 22) or gluten-poor (n = 25) diets. Significant differences (p < 0.05) between groups were assessed using the Wilcoxon test. RESULTS: Both ISBD-affected horses and gluten-rich controls had significantly (p < 0.0004) higher hrTGA titers than gluten-poor controls. However, ISBD horses did not show significantly increased levels of any of the CD related antibodies when compared to gluten-rich controls. Nevertheless, markedly increased antibody levels (TGA, EMA and DGPA) were found in one of the ISBD horses. The introduction of a gluten-free ration in this 14-year-old warmblood stallion resulted after 6 months in the reduction of antibody levels and clinical recovery associated with improved duodenal histopathology. CONCLUSION: To the best of our knowledge, this is the first study assessing gluten-related antibodies in horses and results suggest a potential pathogenic role of gluten in at least some cases of equine ISBD. Clinical importance and impact for human medicine: Given serology and concurrent clinical findings, this study warrants further investigations into the immunologic basis of possible gluten-sensitive enteropathy in horses and analogy with human disease.

The surgical stress response and postoperative immune function after laparoscopic or conventional total mesorectal excision in rectal cancer: a randomized trial.

PURPOSE: This study evaluated differences in stress response and immunological function following laparoscopic and conventional total mesorectal excision (TME) for rectal cancer. METHODS: Patients with non-metastasized rectal cancer were prospectively randomized to open (n = 18) or laparoscopic (n = 22) TME. Blood samples were taken preoperatively (baseline), 2, 24, and 72 h following surgery. Systemic white blood cell and monocyte count, C-reactive protein, interleukin-6 (IL-6), interleukin-8 (IL-8), HLA-DR expression on monocytes, growth hormone, prolactin, and cortisol were measured. RESULTS: Forty patients with a median age of 66 years (interquartile range, 60-74 years) were included. Eighteen patients (45%) were randomized to open surgery and 22 patients (55%) to laparoscopic surgery. Patient demographics in terms of gender, age, BMI, ASA classification, localization of the tumor, and type of neoadjuvant therapy were comparable for both groups. Laparoscopic surgery resulted in a significantly better short-term preservation of postoperative immune function. HLA-DR expression on monocytes was significantly higher (64% vs 50%, P = 0.014) and IL-6 level increase was significantly lower (4.6 vs 10.8, P = 0.003) 2 h after laparoscopic surgery. No differences between the open and laparoscopic technique were observed in postoperative white blood cell count, monocyte count, C-reactive protein, IL-8, growth hormone, prolactin, and cortisol levels. CONCLUSION: Short-term postoperative immune and inflammatory functions tended to be better after laparoscopic rectal surgery. However, the differences were not consistent at all time intervals, making a definitive conclusion difficult. Better preserved inflammatory function 2 h after surgery may reflect a reduction in operative trauma when the laparoscopic technique is compared with open rectal procedures.

Coeliac disease in China, a field waiting for exploration.

BACKGROUND: no systematic studies on the prevalence of coeliac disease (CD) have been reported from China. In western populations CD is more common in patients with insulin dependent diabetes mellitus (IDDM) and in diarrhoea-predominant irritable bowel syndrome (D-IBS). We have screened patients with these conditions presenting to the outpatient department of a large hospital of "Traditional Chinese Medicine" (TCM) in Nanjing, Jiangsu province, P.R. China. METHODS: we tested sera of 78 unrelated Han Chinese patients (5 IDDM and 73 D-IBS), using ELISA serological tests for IgG anti-gliadin antibodies (IgG-AGA) and IgA anti-tissue transglutaminase antibodies (IgA-tTG). RESULTS: six out of 78 patients (7.7%) were positive for IgG-AGA (two men and four women) and two (2.6%) were positive for IgA-tTGs. One of the latter patients was negative for IgG-AGA. Besides, one patient had a dubious IgA-tTG antibody and a positive IgG-AGA. None of the six patients agreed to undergo duodenal biopsy. Two out of these six patients followed a gluten-free diet for one year. In one patient the diarrhoea ceased and his body weight increased. Another stopped losing weight. CONCLUSIONS: this study previously published as a letter in GUT (Wu J, Xia B, von Blomberg BME, Zhao C, Yang XW, Crusius JBA, Peña AS. Coeliac disease: emerging in China? Gut 2010; 59(3): 418-9) demonstrated that CD may exist in the Jiangsu province of P.R. China. The present article draws attention to the difficulties of following a standard protocol in China such as established in western countries and highlights important factors less well known in the west in relation to the development of CD in China. Wheat production became significant in China between 1600 and 1300 B.C. After the Han dynasty (500-200 B.C.), wheat was one of the main cereals in China. One the major wheat fields in China is located in the Jiangsu province where the research for this article was performed. A review of Chinese literature shows that the predominant HLA-DQ CD risk alleles and haplotypes are present in the Jiangsu province. Genetic background, food consumption, and the results of our study suggest that CD should actively be investigated in P.R. China.

Childhood coeliac disease: towards an improved serological mass screening strategy.

BACKGROUND: In 1997-1998, 6127 asymptomatic children aged 2-4 years were screened for coeliac disease (CD) by anti-endomysium (EmA) testing in the Netherlands. After 6 (+/-2) months, biopsies were performed in 57 seropositive children; 31(54%) had villous atrophy, but 26 (46%), all HLA-DQ2/DQ8 positive, had normal histology. AIMS: To reduce the number of unnecessary biopsies after serological mass screening for CD in asymptomatic young children by optimizing screening procedures. METHODS: Comparing different tests and optimizing their cut-off point: screening samples were tested for EmA, tissue-transglutaminase (tTGA), antigliadin and deamidated-gliadin-peptides (anti-DGP) antibodies. Determining serological persistence over time: persistence of EmA and tTGA was determined by testing serological samples obtained at biopsy. RESULTS: Tissue-transglutaminase and anti-DGP correlated with EmA. Optimization of standard cut-off points not only reduced unnecessary biopsies by 50-96% but also reduced sensitivity. EmA persisted in all CD children, but in only 50% of the non-CD children. tTGA persisted in 83% of CD, but in only 15% of non-CD children. CONCLUSIONS: Coeliac disease antibodies may be present transiently in genetically predisposed children. To avoid unnecessary biopsies, serological mass screening procedures may be improved by repeating EmA and/or tTGA in initially seropositive young children after 6 months, before proceeding to biopsy. This may reduce the number of unnecessary biopsies that are performed.

Aberrant T-lymphocytes in refractory coeliac disease are not strictly confined to a small intestinal intraepithelial localization.

BACKGROUND: Refractory coeliac disease (RCD) is characterized by persisting mucosal pathology in spite of a strict gluten free diet (GFD). In RCD type II, phenotypically aberrant (CD7+CD3-CD4/8-cytoplasmicCD3+) T-lymphocytes are present within the intraepitelial lymphocyte (IEL) population in the small intestine, and 50-60% of these patients develops an enteropathy associated T-cell lymphoma (EATL). AIM: To investigate whether aberrant T-lymphocytes in RCD II can be detected in other parts of the small intestinal mucosa besides the intraepithelial compartment. Additionally, the presence of aberrant T-lymphocytes was analyzed in two RCD II patients that developed atypical skin lesions. METHODS: Multiparameter flow cytometric immunophenotyping was performed on both IEL and lamina propria lymphocyte (LPL) cell suspensions, isolated from small bowel biopsy specimens of RCD II patients (n = 14), and on cutaneous lymphocytes isolated from skin-lesion biopsy specimens of RCD II patients (n = 2). In addition, immunofluorescence analysis of frozen RCD II derived small intestinal biopsies was performed. RESULTS: Our results clearly show that aberrant T-lymphocytes may be present in both the IEL and the LPL compartments of RCD II derived small intestinal biopsies. Although the highest percentages are always present in the IEL compartment, aberrant LPL can exceed 20% of total LPL in half the RCD II patients. Interestingly, cutaneous lymphocytes isolated from atypical skin lesions that developed in some RCD II patients showed a similar aberrant immunophenotype as found in the intestinal mucosa. CONCLUSIONS: In RCD II, the aberrant T-lymphocytes may also reside in the subepithelial layer of the small intestinal mucosa, in the lamina propria, and even in extraintestinal localizations including the skin. Whether this phenomenon represents a passive overflow from the intestinal epithelium or active trafficking towards other anatomical localizations remains to be elucidated. RCD II appears to be a disseminated disease, which may impose the risk of EATL development outside the intestine.

Differential suppression of dendritic cell cytokine production by anti-inflammatory drugs.

BACKGROUND: Various anti-inflammatory drugs are available for the treatment of skin disorders. In these diseases, untoward immune responses to endogenous and/or environmental antigens are initiated by maturation and polarization of dendritic cells (DC). OBJECTIVE: To explore the suppressive effects of anti-inflammatory drugs on DC maturation and, in particular, polarization. METHODS: Exposure of DC to nickel in vitro results in DC maturation and secretion of both type 1 and type 2 cytokines, thereby providing a model to study the effects of anti-inflammatory drugs on DC responses. The inhibitory effects of anti-inflammatory drugs (ciclosporin, dexamethasone, diclofenac, dimethylfumarate, hydrocortisone, lactoferrin, 1-alpha,25-dihydroxyvitamin D3) on DC maturation (CD83, CD86, HLA-DR, CXCL8) and polarization (type 1: IL-12p70, TNF-alpha; type 2: IL-10, CCL17) were studied. RESULTS: All anti-inflammatory drugs, except for lactoferrin, had inhibitory effects on DC maturation. Hydrocortisone and dexamethasone exclusively suppressed the release of type 1 cytokines. A less pronounced, but similar profile was observed for dimethylfumarate and 1-alpha,25-dihydroxyvitamin D3. Ciclosporin suppressed both type 1 and 2 cytokines. In contrast, diclofenac suppressed only type 2 DC cytokine secretion. CONCLUSION: The present results give more insight into the pharmacological effects of immunosuppressive drugs on the immune system, and can thereby contribute to a more rational selection of anti-inflammatory drugs for the treatment of inflammatory skin disorders.

No evidence of misdiagnosis in patients with multiple sclerosis and repeated positive anticardiolipin antibody testing based on magnetic resonance imaging and long term follow-up.

OBJECTIVE: To determine whether patients with definite multiple sclerosis (MS) and repeated positive anticardiolipin antibody (aCL Ab) testing fulfil the recently updated criteria for the antiphospholipid syndrome (APS). Also, to determine if these patients form a separate subgroup in terms of long term follow-up and MRI characteristics. DESIGN: A blinded case control study comparing MRI patterns between aCL Ab positive and negative MS patients with a clinical follow-up of 7 years. PARTICIPANTS: 8 (5.6%; male:female ratio 2:6; 6 relapsing-remitting subtype, 1 primary progressive subtype and 1 neuromyelitis optica (NMO)) of 143 consecutive patients with definite MS or NMO (71% relapsing-remitting, 18% secondary progressive and 6% primary progressive disease course; 4% NMO) showed repeated positive aCL Ab testing. SETTING: Outpatient clinic of a tertiary MS centre in The Netherlands. RESULTS: All eight aCL Ab positive patients had levels below 40 MPL/GPL units, with the majority of intervals between tests of at least 12 weeks. After follow-up, none of the patients fulfilled the criteria for APS. No specific MRI features were present compared with 24 matched aCL Ab negative patients. CONCLUSIONS: No aCL Ab positive MS patient fulfilled the criteria for APS, arguing against a possible misdiagnosis or coexistence.

Survival in refractory coeliac disease and enteropathy-associated T-cell lymphoma: retrospective evaluation of single-centre experience.

BACKGROUND: Coeliac disease may be regarded as refractory disease (RCD) when symptoms persist or recur despite strict adherence to a gluten-free diet. RCD may be subdivided into types I and II with a phenotypically normal and aberrant intraepithelial T-cell population, respectively. RCD I seems to respond well to azathioprine/prednisone therapy. RCD II is usually resistant to any known therapy and transition into enteropathy-associated T-cell lymphoma (EATL) is common. AIM: To provide further insight into RCD and the development of EATL, by reporting on long-term survival and risk of transition of RCD into EATL in a large cohort of patients with complicated coeliac disease. DESIGN AND METHODS: Retrospective comparison of responses to therapy in four groups of patients with complicated coeliac disease: 43, RCD I; 50, RCD II (total), of whom 26 with RCD II developed EATL after a period of refractoriness to a gluten-free diet (secondary EATL) and 13 were EATL patients without preceding history of complicated coeliac disease (de novo EATL). RESULTS: No coeliac-disease-related mortality was recognised in the RCD I group. The overall 5-year survival in the RCD I group it was 96%; in the RCD II (total) group was 58%; and in the RCD II group after developing EATL it was only 8%. The 2-year survival in the de novo EATL group was 20% versus 15% in secondary EATL group (p = 0.63). Twenty-eight (56%) of the 50 patients with RCD II died, 23 (46%) due to EATL, 4 due to a progressive refractory state with emaciation and 1 from neurocoeliac disease. CONCLUSION: Remarkably, no patient with RCD I developed RCD II or EATL within the mean follow-up period of 5 years (range 2-15 years). A total of 52% of the RCD II patients developed EATL within 4-6 years after the diagnosis of RCD II. More aggressive and targeted therapies seem necessary in RCD II and EATL.

Melanoma-specific tumor-infiltrating lymphocytes but not circulating melanoma-specific T cells may predict survival in resected advanced-stage melanoma patients.

PURPOSE: To study the effect of autologous tumor cell vaccinations on the presence and numbers of circulating CD8+ T cells specific for tumor-associated antigens (TAA) in metastatic melanoma patients. To investigate the correlation between the presence of tumor-infiltrating lymphocytes (TIL) and circulating TAA-specific CD8+ T cells before and after autologous tumor cell vaccination with overall survival. EXPERIMENTAL DESIGN: Twenty-five stage III and resected stage IV metastatic melanoma patients were adjuvantly treated with a series of intracutaneously injected autologous tumor cell vaccinations, of which the first two contained BCG as an immunostimulatory adjuvant. Tumor samples and blood samples obtained before and after vaccination of these patients were studied for the presence of TAA-specific T cells using HLA-tetramers and results were correlated with survival. RESULTS: In 5 of 17 (29%) melanoma patients, circulating TAA-specific T cells were detectable prior to immunizations. No significant changes in the frequency and specificity were found during the treatment period in all patients. Presence of circulating TAA-specific T cells was not correlated with survival (log rank, P=0.215). Inside melanoma tissue, TAA-specific TIL could be detected in 75% of 16 available tumor samples. In case of detectable TAA-specific TIL, median survival was 22.5 months compared to median survival of 4.5 months in case of absence of TAA-specific T cells (log rank, P=0.0094). In none of the patients, TAA-specific T cells were found both in tumor tissue and blood at the same time. CONCLUSIONS: These data suggest that the presence of TAA-specific TILs forms a prognostic factor, predicting improved survival in advanced-stage melanoma patients. The absence of TAA-specific T cells in the circulation suggests that homing of the tumor-specific T cell population to the tumor site contributes to the effectiveness of antitumor immunity.

CXCL8 secretion by dendritic cells predicts contact allergens from irritants.

Monocyte-derived dendritic cell functions have been explored for identification of contact allergens in vitro. Current methods, including measurement of changes in cell surface marker expression (e.g. CD83, CD86) do not provide a sensitive method for detecting the sensitising potential of a chemical. In this study, we investigated whether chemokine production by monocyte-derived dendritic cells is increased upon maturation and whether chemokine production can provide methodology for the detection of allergens. Monocyte-derived dendritic cells were exposed to allergens (nickel sulphate, cobalt chloride, palladium chloride, copper sulphate, chrome-(III)-chloride, potassium dichromate, p-phenylenediamine and dinitrochlorobenzene) and irritants (sodium dodecyl sulphate, dimethylsulphoxide, benzalkoniumchloride and propane-1-ol). CD83 and CD86 expression was analysed by flow cytometry and chemokine production (CXCL8, CCL5, CCL17, CCL18, CCL19, CCL20, CCL22) was determined by ELISA. Significant up regulation of CD83 and CD86 expression could only be induced by three out of seven and five out of seven allergens, respectively. In contrast, CXCL8 production was significantly increased after stimulation with all allergens tested, whereas irritant exposure led to decreased CXCL8 production. All other chemokines tested, failed in identifying contact allergens. In conclusion, CXCL8 production, next to CD83 and CD86 up regulation, by monocyte-derived dendritic cells provides a promising in vitro tool for discrimination between allergens and irritants.

Regulation of nickel-induced T-cell responsiveness by CD4+CD25+ cells in contact allergic patients and healthy individuals.

In this study, we investigated the capacity of CD4+CD25+ regulatory T cells to suppress nickel-specific effector T cells, both in nickel-allergic patients and healthy controls. CD4+ cells isolated from allergic patients showed an increased proliferative response to nickel, whereas CD4+ cells from negative controls did not respond to allergen. When CD4+CD25+ cells were depleted, nickel-specific responsiveness was strongly increased both in allergic and in non-allergic individuals, with the most pronounced effect in allergic patients. These regulatory T cells were anergic to nickel but inhibited nickel-specific CD4+CD25- effector T cells in coculture experiments. CD4+CD25+ cells from nickel-allergic patients showed only a limited capacity to suppress effector T-cell responsiveness, because an increased nickel reactivity could still be detected in these cocultures. None of the isolated CD4+CD25+ cells, either isolated from healthy controls or allergic patients, produced IL-10 in response to nickel. Overall, these results support the view that CD4+CD25+ cells can control the activation of nickel-specific effector T cells in non-allergic individuals, whereas this regulatory capacity is impaired in allergic patients. To investigate the presence of allergen-specific regulatory T cells in truly naïve, non-sensitized individuals, T-cell reactivity should also be studied with non-environmental contact allergens, such as para-phenylenediamine.

Induction of cytokine (interleukin-1alpha and tumor necrosis factor-alpha) and chemokine (CCL20, CCL27, and CXCL8) alarm signals after allergen and irritant exposure.

The immune system is called into action by alarm signals generated from injured tissues. We examined the nature of these alarm signals after exposure of skin residential cells to contact allergens (nickel sulfate and potassium dichromate) and a contact irritant [sodium dodecyl sulfate (SDS)]. Nickel sulfate, potassium dichromate, and SDS were applied topically to the stratum corneum of human skin equivalents. A similar concentration-dependent increase in chemokine (CCL20, CCL27, and CXCL8) secretion was observed for all three chemicals. Exposure to nickel sulfate and SDS was investigated in more detail: similar to chemokine secretion, no difference was observed in the time- and concentration-dependent increase in pro-inflammatory cytokine [interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha)] secretion. Maximal increase in IL-1alpha secretion occurred within 2 h after exposure to both nickel sulfate and SDS and prior to increased chemokine secretion. TNF-alpha secretion was detectable 8 h after chemical exposure. After allergen or irritant exposure, increased CCL20 and CXCL8, but not CCL27, secretion was inhibited by neutralizing human antibodies to either IL-1alpha or TNF-alpha. Our data show that alarm signals consist of primary and secondary signals. IL-1alpha and TNF-alpha are released as primary alarm signals, which trigger the release of secondary chemokine (CCL20 and CXCL8) alarm signals. However, some chemokines, for example, CCL27 can be secreted in an IL-1alpha and TNF-alpha independent manner. Our data suggest that skin residential cells respond to both allergen and irritant exposure by releasing mediators that initiate infiltration of immune responsive cells into the skin.