Peripheral blood mononuclear cells from IgE- and non-IgE-associated allergic atopic eczema/dermatitis syndrome (AEDS) demonstrate increased capacity of generating interleukin-13 but differ in their potential of synthesizing interferon-gamma

BACKGROUND: A subgroup of patients with allergic atopic eczema/dermatitis syndrome (AEDS) are known to have normal total and specific IgE levels and negative skin prick tests towards common environmental allergens. This form of the disease has been termed non-IgE-associated allergic AEDS. Although allergic mechanisms appear to be important, the pathogenesis of both IgE- and non-IgE-associated forms of the disease is unknown. METHODS: We have compared the cytokine production pattern of peripheral blood mononuclear cells (PBMC) from IgE-associated AEDS, non-IgE-associated AEDS, and normal control individuals. PBMC were stimulated with anti-CD3 and/or anti-CD28 monoclonal antibodies (mAb) and cytokine production was measured by immunoassays in supernatants of 24-h cultures. RESULTS: Compared to healthy subjects and non-IgE-associated AEDS patients, stimulated PBMC from IgE-associated AEDS patients produced less interferon (IFN)-gamma. However, stimulated PBMC from both IgE-associated AEDS and non-IgE-associated AEDS patients produced more interleukin (IL)-13 than PBMC from control individuals. Moreover, IL-5 production was significantly increased in non-IgE-associated AEDS but not in IgE-associated AEDS patients. CONCLUSIONS: The underlying mechanism leading to increased differentiation of T helper (Th) 2 cells may involve a deficient capacity in producing IFN-gamma in IgE-associated AEDS but not in non-IgE-associated AEDS patients. IL-13 may be a key cytokine in the pathogenesis of both allergic forms of AEDS.     

Birch pollen-related food as a provocation factor of allergic symptoms in children with atopic eczema/dermatitis syndrome

BACKGROUND: Food allergy to cow's milk or hen's egg is a common problem in children with atopic eczema/dermatitis syndrome (AEDS) but the role of birch pollen-related food for the induction of allergic symptoms is still not clear. PATIENTS/METHODS: Twelve children (median age 5 years) with AEDS underwent an oral challenge with those birch pollen-related foods which were reported to induce no immediate symptoms, but were consumed on a regular basis. Total IgE and specific IgE to birch pollen, Bet v 1/2 and various birch pollen-related foods were determined. RESULTS: Seven of 12 children showed immediate and/or late eczematous reactions upon ingestion of birch pollen-related foodstuff. Four children showed a worsening of eczema 24 h upon oral challenge with a significant difference in SCORAD before and after challenge. There were no differences in terms of total IgE or birch pollen-specific IgE between children with a late eczematous response and non-reacting children. CONCLUSIONS: Birch pollen-related food may induce allergic symptoms in children with AEDS who exhibit a sensitization to birch pollen. Oral challenge tests should be performed in those children who suffer from severe AEDS and who are highly sensitized to birch pollen allergens even in the absence of a history suggestive of food allergy.     

IgE on Langerhans cells in the skin of patients with atopic dermatitis and birch allergy

Epidermal cell suspensions from the skin of seven patients with atopic dermatitis (AD) and seven healthy non-atopic controls were investigated for the presence of surface HLA-DR and CD1 antigen, and IgE using indirect and double-staining immunofluorescence techniques. Fifty-seven percent of all CDI + and 68% of all HLA-DR + cells from the patients demonstrated IgE on their surface, indicating that Langerhans cells (Lc) in AD may be a heterogeneous population with regard to surface characteristics. No IgE + cells were found in the epidermal cell suspensions from the healthy non-atopic controls. An attempt lo demonstrate birch pollen antigen on the surface of Lc from the same patients all strongly allergic to birch pollen, using indirect immunofluorescence techniques, was unsuccessful, also after in vitro incubation of the Lc with high concentration of the birch antigen.     

Pulmonary dendritic cells and alveolar macrophages are regulated by gammadelta T cells during the resolution of S. pneumoniae-induced inflammation

gammadelta T cells commonly associate with mucosal and epithelial sites, fulfilling a variety of immunoregulatory functions. While lung gammadelta T cells have well-characterized pro-inflammatory activity, their potential role in the resolution of lung inflammation has yet to be explored in any detail. Indeed, given the importance of minimizing inflammation, the cellular mechanisms driving the resolution of lung inflammation are poorly understood. Using a murine model of acute Streptococcus pneumoniae-mediated lung inflammation, we now show that resolution of inflammation following bacterial clearance is associated with a > 30-fold increase in gammadelta T-cell number. Although inflammation eventually resolves in TCR delta(-/-) mice, elevated numbers of alveolar macrophages and pulmonary dendritic cells, and the appearance of well-formed granulomas in lungs of TCR delta(-/-) mice, together indicated a role for gammadelta T cells in regulating mononuclear phagocyte number. Ex vivo, both alveolar macrophages and pulmonary dendritic cells were susceptible to lung gammadelta T cell-mediated cytotoxicity, the first demonstration of such activity against a dendritic cell population. These findings support a model whereby expansion of gammadelta T cells helps restore mononuclear phagocyte numbers to homeostatic levels, protecting the lung from the consequences of inappropriate inflammation.     

Response of lung gammadelta T cells to experimental sepsis in mice

Gammadelta T cells link innate and adaptive immune systems and may regulate host defence. Their role in systemic inflammation induced by trauma or infection (sepsis) is still obscured. The present study was aimed to investigate functions of lung gammadelta T cells and their response to experimental sepsis. Mice were subjected to caecal ligation and puncture (CLP) to induce sepsis and acute lung injury (ALI), or to the sham operation. Animals were killed 1, 4, and 7 days postoperatively; lungs were examined by histology, and isolated cells were studied by flow cytometry. Absolute number of gammadelta T cells progressively increased in lungs during sepsis, and reached a seven-fold increase at day 7 after CLP (3.84 +/- 0.41 x 10(5)/lung; P = 0.0002 versus sham). A cellular dysfunction was revealed one day after CLP, as manifested by low cytolytic activity (22.3 +/- 7.1%; P < 0.05 versus sham), low interferon-gamma (IFN-gamma; 8.5 +/- 2.5%; P < 0.05 versus control) and interleukin-10 (IL-10) expression, and high tumour necrosis factor-alpha expression (19.5 +/- 1.7%; P < 0.05 versus control). The restoration of cytotoxicity, and increase in IFN-gamma and IL-10 expression was observed at day 7 of CLP-induced sepsis. In summary, our results demonstrate significant progressive accumulation of gammadelta T cells in lungs during CLP-induced ALI. The temporary functional suppression of lung gammadelta T cells found early after CLP may influence the outcome of sepsis, possibly being associated with uncontrolled inflammatory lung damage.     

Yes T cells, but three different T cells (alphabeta, gammadelta and NK T cells), and also B-1 cells mediate contact sensitivity

Transfer of contact sensitivity (CS) responses by immune lymphoid cells was the first finding that distinguished cellular from humoral immunity. CS has remained the most studied T cell reaction in vivo, and is the prototype for a variety of delayed-type hypersensitivity (DTH) responses. DTH in essence is the recruitment of effector alphabeta-T cells out of vessels into peripheral tissues. The T cells then are activated by antigen presenting cells to produce pro-inflammatory cytokines. It has been assumed that the alphabeta-T cells alone are responsible, but recent studies show that three other lymphocyte subsets are involved: CS-inducing NK T cells, CS-initiating B-1 cells, and CS-assisting gammadelta-T cells. Therefore, the effector alphabeta-T cells are essential, but cannot be recruited into the tissues without the local action of IgM antibodies produced by B-1 cells rapidly (1 day) post-immunization. The IgM complexes with the challenge antigen to locally activate complement to lead to vascular activation required for T cell recruitment. This process occurs early (1-2 hours) in the elicitation phase, and is called CS-initiation. The essential CS-inducing NK T cells activate the B-1 cells by producing IL-4 rapidly (1 hour) after immunization, and gammadelta-T cells assist the local inflammatory function of the recruited CS-effector alphabeta-T cells. Thus, four lymphocyte subsets are required for elicitation of responses: CS-inducing NK T cells, CS-initiating B-1 cells, CS-assisting gammadelta-T cells, and finally the CS-effector alphabeta-T cells. Three of these four cell types are present in the immune lymphoid cell population that adoptively transfers CS: B-1 cells, gammadelta-T cells, and the alphabeta-T cells.     

gammadelta T cells condition dendritic cells in vivo for priming pulmonary CD8 T cell responses against Mycobacterium tuberculosis

gammadelta T cells and dendritic cells are quickly recruited to the lungs shortly after intranasal vaccination with BCG, but the functional in vivo interplay between these two cell populations and its role in the induction of adaptive immune responses is unclear. Using TCR-deficient mice and bone marrow chimeras, we show here that gammadelta T cells provide a non-redundant early source of IFN-gamma in vivo, which enhances IL-12 production by lung dendritic cells. The in vivo-conditioned dendritic cells, in turn, prime a more efficient lung CD8 T cell response against Mycobacterium tuberculosis. Thus, strategies exploiting gammadelta T cell function and IFN-gamma production could be valuable for the design and testing of mucosal vaccines.     

Breast-feeding and atopic eczema dermatitis syndrome: protective or harmful?

Numerous studies have addressed the potential of breast-feeding to protect for the development of allergic diseases, and in particular of atopic eczema dermatitis syndrome (AEDS). Although the majority of studies, as well as several meta-analyses, are strongly in favour of breast-feeding, there are some conflicting results and open issues. Furthermore, breast-feeding might be detrimental in a subgroup of young infants with severe early manifestations of AEDS and immunoglobulin E sensitizations to common foods. The aim of this review is not to analyse systematically the current literature, but to suggest a scientifically and clinically based analysis of the benefits of breast-feeding in atopic infants.     

CD4(+)IL-13(+) cells in peripheral blood well correlates with the severity of atopic dermatitis in children

BACKGROUND: In atopic dermatitis (AD) a Th1/Th2 imbalance has been reported, and interleukin (IL)-13 seems to play a pivotal role in the inflammatory network. We tried to assess the correlation between the immunological marker CD4(+)IL-13(+) and the clinical phase of extrinsic AD in children. METHODS: Twenty children with AD were studied. Assessed parameters were: clinical severity (SCORAD index), total serum immunoglobulin E (IgE), blood eosinophil count, and percentage of CD4(+)IFNgamma(+), CD4(+)IL-4(+), CD4(+)IL-13(+) T cells. Determinations were carried out in the acute phase and after clinical remission were achieved. Ten nonatopic-matched children served as controls. RESULTS: At baseline, AD was mild in 25%, moderate in 50% and severe in 25% of children. In the acute phase a significant relationship between the eosinophil count and the SCORAD index was found (P = 0.0001). Blood CD4(+)IL-4(+) were significantly higher in the AD group (median 17.0, range: 13.7-21.4) than in controls (12.6, 6.4-17.2, P < 0.0001). CD4(+)IL-13(+) cells in the AD group well correlated (P = 0.0007) with SCORAD index. At remission, a significant correlation between SCORAD index and eosinophil count was found (P < 0.03) and the percentage of CD4(+)IL-13(+) cells globally decreased (P < 0.0001), while no difference was found among SCORAD classes. CONCLUSION: This study confirms the Th2 profile predominance in the peripheral blood of children with AD, and evidences close relationship between the number of CD4(+)IL-13(+) T cells and the disease's severity.     

Respiratory syncytial virus infection suppresses IFN-gamma production of gammadelta T cells

The immunological mechanisms by which respiratory syncytial virus (RSV) contributes to the development of asthma are poorly understood. gammadelta T cells are important in mucosal defence, and may contribute to the establishment of primary immune responses by producing cytokines early during respiratory infections. Thus, we used flow cytometry and intracellular cytokine staining to investigate the expression of interferon (IFN)-gamma and interleukin (IL)-4 by mitogen-stimulated gammadelta T cells from the peripheral blood of 15 hospitalized infants with RSV bronchiolitis, seven rotavirus-infected infants and eight normal controls. gammadelta T cells from RSV-infected infants had a lower proportion of IFN-gamma-producing cells (median, 4.00%; range, 0.58-6.60%) and a slightly but significantly higher proportion of IL-4-producing cells (median, 0.40%; range, 0.13-2.76%) than rotavirus-infected infants (median, 32.10%; range, 14.43-61.21%; P < 0.01, median, 0.00%; range, 0.00-0.00%; P < 0.05) in the acute phase. By contrast, differences in cytokine production by total CD3+ T cells did not differ significantly between patient groups. Thus, reduced IFN-gamma-production by gammadelta T cells in the peripheral blood of RSV-infected infants is accompanied by increased Th2 cytokine production during the acute phase of disease. At follow-up, eight children had recurrent episodes of wheezing. The frequencies of IFN-gamma-producing gammadelta T cells were significantly lower in patients who developed recurrent wheezing (median, 0.65%; range, 0.02-1.75%) than in patients without recurrent wheezing (median, 6.90%; range, 5.25-10.98%; P < 0.005). Cytokine production by gammadelta T cells may therefore be important in the pathogenesis of acute RSV disease, and play a part in the development of recurrent childhood wheezing after bronchilolitis.     

Characterization of monocyte subtypes in the allergic form of atopic eczema/dermatitis syndrome

BACKGROUND: Monocyte (Mo) subsets exhibiting distinct phenotypic and functional properties identified in peripheral blood are assumed to be under the control of soluble factors from their surrounding micromilieu. Atopic eczema/dermatitis syndrome (AEDS) is accompanied by humoral and cellular alterations among which an increased expression of the high-affinity receptor for IgE (Fc epsilon RI) on antigen presenting cells, like Mo, could be found. Therefore we analyzed the assembly of circulating Mo populations and their Fc epsilon RI surface expression during the course of AEDS. METHODS: Blood samples were taken from AEDS patients before and after topical treatment as well as from psoriasis patients and healthy control donors. Detailed analysis of Mo subsets was done by flow cytometry. Meticulous clinical scoring included quantification of the surface damage using the eczema area and severity index (EASI score) as well as evaluation of the serum level of thymus- and activation-regulated chemokine (TARC); this was done before and after 2 weeks of topical treatment with tacrolimus ointment 0.1%. RESULTS: During the exacerbation phase of AEDS, patients harboured a different assembly of Mo subtypes from normal nonatopic individuals and patients with psoriasis with a significant increased population of CD14(+)CD64(-) CD16(+) Mo. Clinical improvement led to a significant decrease of this subpopulation in favor of CD14(+)CD64(+)CD16(-) Mo, leading to a composition of Mo subsets similar to the state found in healthy donors. Interestingly, Fc epsilon RI expression was confined to the CD14(+)CD64(+)CD16(-) Mo subpopulation and the percentage of this Fc epsilon RI(+) Mo subset increased significantly in the peripheral blood after topical treatment. CONCLUSION: Our data provide for the first time clear evidence that fluctuations of Mo subsets in AEDS might reflect qualitatively and quantitatively distinct contributions of Mo subsets to the development of AEDS.     

Increased levels of urinary leukotriene E4 in children with severe atopic eczema/dermatitis syndrome

BACKGROUND: Leukotrienes are thought to play a role in the pathogenesis of atopic eczema/dermatitis syndrome (AEDS). Urinary leukotriene E4 (U-LTE4) is a marker of whole-body cysteinyl-leukotriene production. AIMS OF THE STUDY: To evaluate the role of leukotrienes in children with AEDS by measuring levels of U-LTE4, and to evaluate whether levels of U-LTE4 may reflect disease activity and allergic sensitization in AEDS. METHODS: U-LTE4 was measured by enzyme-linked immunosorbent assay in 87 children with mild (n=32), moderate (n=34) and severe (n=21) AEDS, as well as in 72 nonatopic healthy controls. Fifty-eight of the children with AEDS were sensitized to common allergens, and 29 were not. RESULTS: Levels of U-LTE4 were higher in children with severe AEDS (140; 66-166 microg/mmol creatinine, median; quartiles) than in controls (52; 30-90, P <0.05), whereas levels of U-LTE4 in moderate and mild disease were similar to controls. U-LTE4 levels were similar in children with or without sensitization to common allergens, but severe AEDS children with sensitization had higher levels of U-LTE4 than those without sensitization. CONCLUSION: The results suggest a role for leukotrienes in the pathogenesis of severe AEDS, and may support a role for leukotriene-antagonists in the treatment of this disorder. Levels of U-LTE4 may reflect the disease severity and sensitization to allergens in AEDS.     

Reciprocal stimulation of gammadelta T cells and dendritic cells during the anti-mycobacterial immune response

Gammadelta T cells and dendritic cells (DC) are two distinct cell types of innate immunity that participate in early phases of immune response against Mycobacterium tuberculosis infection. Here we show that a close functional relationship exists between these cell populations. Using an in vitro coculture system, Vgamma1 T cells from Tcrb(-/- )mice were found to be activated by DC infected in vitro with BCG, as indicated by the elevated CD69 expression, IFN-gamma secretion and cytotoxic activity. This activation process was due to a non-cognate mechanism since it required neither cell to cell contact nor interaction between the TCR and a specific antigen, but was mediated by DC-derived IL-12. Reciprocally, Vgamma1 T cells provided a key cytokine, IFN-gamma, which increased IL-12 production by BCG-infected DC. Moreover, exposure of BCG-infected DC to Vgamma1 T cells conditioned the former to prime a significantly stronger anti-mycobacterial CD8 T cell response. Consequently, stimulation of gammadelta T cells and their non-cognate interaction with DC could be applied as an immune adjuvant strategy to optimize vaccine-induced CD8 T cell immunity.     

Urinary leukotriene levels are increased during exacerbation of atopic eczema/dermatitis syndrome. Relation to clinical status

BACKGROUND: Leukotrienes are potent mediators of allergic inflammation and their role in the pathogenesis of allergic disorders, particularly asthma, is well established. Their importance in the pathogenesis of atopic eczema/dermatitis syndrome (AEDS) is still unclear. We aimed to compare urinary cysteinyl leukotriene (Cys-LT) levels during exacerbation and remission of AEDS in relation to clinical status, IgE levels, and eosinophil counts. METHODS: Urinary Cys-LTs were measured by direct enzyme immunoassay in 17 adult patients with AEDS and in 17 healthy controls in whom atopy had been excluded. Cys-LTs were compared during exacerbation and remission of AEDS in relation to the clinical status measured by SCORAD. Total IgE levels were measured by enzyme-linked immunoassay (ELISA). RESULTS: Mean clinical score during the exacerbation was 64.3 +/- 3.1 and during remission 22.4 +/- 4 (P < 0.01). Cys-LTs levels were significantly higher during the exacerbation of AEDS than in the control group (230.9 +/- 20.8 vs 123.2 +/- 9.9 pg/mg creatinine; P < 0.005). During the remission, the difference between AEDS patients and the control group was not significant (96.3 +/- 8.7 vs 123.2 +/- 9.9 pg/mg creatinine; P = 0.8). During AEDS exacerbation Cys-LTs levels were significantly correlated with the clinical status (rS = 0.73, P < 0.01) and with eosinophil counts (r = 0.86; P < 0.01) but not with the duration of the disease, age of patients, or IgE levels. CONCLUSIONS: Our results point to enhanced biosynthesis of Cys-LTs during the AEDS exacerbations. Inflammatory cells, e.g. eosinophils are the most probable source of Cys-LTs. A strong correlation between Cys-LT levels and clinical status may in part explain preliminary clinical observations of efficacy of leukotriene antagonists in alleviating symptoms of AEDS.     

TCR-beta chains derived from peripheral gammadelta T cells can take part in alphabeta T-cell development

Between 10 and 20% of the peripheral gammadelta T cells express cytoplasmic TCR-beta proteins, but whether such TCR-beta chains can partake in alphabeta T-cell development has never been systematically investigated. Therefore, we reconstituted the T-cell compartment of CD3epsilon-deficient mice with Pax5-TCR-beta deficient proB cells expressing, via a retroviral vector, TCR-beta chains from either peripheral gammadelta or alphabeta T cells. Recipient thymi reconstituted with proB cells containing empty vector were small (<15x10(6) cells), contained few gammadelta T but no alphabeta T cells. In contrast, thymi from mice receiving proB cells containing gammadelta or alphabeta T-cell-derived TCR-beta chains contained 80-130x10(6) cells, and showed a normal CD4, CD8 and alphabeta TCR expression pattern. However, regardless of the source of TCR-beta chain, reconstituted mice rapidly showed signs of autoimmunity dying 5-15 wk following reconstitution. Autoimmune disease induction could be prevented by co-transfer of Treg cells thereby allowing the functionality of the generated T cells to be assessed. Results obtained show that TCR-beta chains from gammadelta T cells can efficiently take part in alphabeta T-cell development. The implications of these findings for gammadelta T-cell development will be discussed.     

WC1+ gammadelta T cell memory population is induced by killed bacterial vaccine

Limited studies have addressed the ability of gammadelta T cells to become memory populations. We previously demonstrated that WC1.1(+) gammadelta T cells from ruminants vaccinated with killed Leptospira borgpetersenii proliferate and produce IFN-gamma in recall responses. Here we show that this response is dependent upon antigen-responsive CD4 T cells, at least across transwell membranes; this requirement cannot be replaced by IL-2. The response was also dependent upon in vivo priming, since gammadelta T cells from leptospira vaccine-naive animals did not respond to antigen even when co-cultured across membranes from antigen-responsive PBMC. Gammadelta T cells were the major antigen-responding T cell population for the first 4 wks following vaccination and replicated more rapidly than CD4 T cells. Primed WC1(+) gammadelta T cells circulated as CD62L(hi)/CD45RO(int)/CD44(lo), characteristics of T(CM) cells. When stimulated with antigen, they decreased CD62L, increased CD44 and CD25, and had no change in CD45RO expression. These changes paralleled those of the leptospira antigen-responsive CD4 T cells but differed from those of gammadelta T cells proliferating to mitogen stimulation. This system for in vivo gammadelta T cell priming is unique, since it relies on a killed antigen to induce memory and may be pertinent to designing vaccines that require type 1 pro-inflammatory cytokines.