Allergen-specific helper T cell response in patients with cow's milk allergy: Simultaneous analysis of proliferation and cytokine production by carboxyfluorescein succinimidyl ester dilution assay

The Use of Dual-Cell-Tracker Dye Staining for the Identification and Characterization of Peanut-Specific T-Cell Subsets

Cell-tracker fluorescent dye labeling is widely used for investigating antigen-specific immune responses in vitro and in vivo. Here we describe a development of this technique-the use of dual-cell-tracker dye staining for the identification and characterization of the responses of different T-cell subsets to peanut proteins in vitro.

Oral Food Desensitization in Children With IgE-Mediated Cow's Milk Allergy: Immunological Changes Underlying Desensitization

Purpose

This study aimed to evaluate the safety and efficacy to induce clinical desensitization to cow's milk (CM) of an oral immunotherapy (OIT) protocol in a pediatric population with cow's milk allergy (CMA). In addition, the immune responses against β-casein, of peripheral blood mononuclear cells (PBMCs) from CMA patients, before and after the protocol were evaluated and compared to a nonallergic population.

Methods

A group of 20 children with IgE-mediated CMA and 15 nonallergic children were recruited. Allergic subjects underwent an OIT protocol based on weekly doses of commercial semi-skimmed ultra-high temperature treated (UHT) CM, followed by a maintenance phase. Immune profiles and changes in all subjects were investigated by measuring Th1, Th2, and Treg cytokines, transcription factors, and specific IgE and IgG4 levels.

Results

The CM-OIT protocol enabled to desensitize 70% of the allergic patients. Successful OIT was accompanied by significant increases in casein-specific IgG4 levels, together with a reduction in the concentration of antigen-specific IgE and in IL-5, IL-13, and IL-10 production by β-casein-stimulated PBMCs. Baseline significant differences observed between allergic and nonallergic children in IL-13 and IL-5 levels were no longer found once the protocol had finished.

Conclusions

The OIT protocol was safe and effective in inducing milk desensitization in 70% of the children with CMA, leading to alterations in their immune profiles toward a nonallergic phenotype.

Multicolor flow-cytometric analysis of milk allergen-specific T-helper type 2 cells revealed coexpression of interleukin-4 with Foxp3

BACKGROUND

Allergen-specific T-helper type 2 (TH2) cells play an important role in the development of allergic inflammation; however, investigations of the properties of allergen-specific T cells have been challenging in humans. Despite clear evidence that forkhead box p3 (Foxp3) is expressed in conventional effector T cells, its function has remained unknown.

OBJECTIVE

To characterize allergen-specific TH2 cells in milk allergy, with particular focus on the expression of Foxp3.

METHODS

Twenty-one children with milk allergy and 11 children without milk allergy were studied. Peripheral blood mononuclear cells from subjects were stimulated with milk allergen for 6 hours and analyzed using multicolor flow cytometry to identify CD154(+) allergen-specific T-helper cells. Simultaneously, the expression of intracellular cytokines and Foxp3 was analyzed.

RESULTS

The milk allergy group had significantly larger numbers of milk allergen-specific interleukin (IL)-4- and IL-5-producing CD4(+) T cells than the control group. Subjects in the milk allergy group had significantly more CD154(+)CD4(+) IL-10-producing cells and CD154(+)Foxp3(+)CD4(+) cells than those in the control group. In addition, the number of milk allergen-specific CD154(+)Foxp3(+)CD4(+) cells strongly correlated with that of CD154(+)IL4(+)CD4(+) cells. Bcl-2 expression in CD154(+)IL-4(+)Foxp3(+) T-helper cells was significantly lower compared with that in total CD4 cells.

CONCLUSION

Increased numbers of IL-4-producing allergen-specific T-helper cells were found in patients with milk allergy. In addition, Foxp3 was coexpressed with IL-4 in allergen-specific TH2 cells from patients. This coexpression was associated with lower Bcl-2 levels and could contribute to the phenotype and function of TH2 cells.

Casein-specific IL-4- and IL-13-secreting T cells: a tool to implement diagnosis of cow's milk allergy

BACKGROUND

Cow's milk allergy (CMA) is a frequent food allergy in young children. The oral food challenge is the gold standard for diagnosis, and there is currently no reliable biological test. Our aim was to evaluate the diagnostic potential of a functional assay quantifying allergen-specific Th2 cells in CMA children.

METHODS

A total of 29 children aged 2.8-10.5 years underwent a double-blind, placebo-controlled food challenge (DBPCFC) to cow's milk. Blood was collected before performing the DBPCFC, and peripheral mononuclear cells were cultured in an 18-h ELISpot assay with casein, α-lactalbumin, or β-lactoglobulin. Numbers of antigen-specific IL-4- and IL-13-secreting lymphocytes and serum-specific IgE, IgG4, and total IgE levels were assessed. Receiver operating characteristic (ROC) curves were generated.

RESULTS

A total of 17 (59%) children reacted to cow's milk and were therefore considered as allergic to cow's milk (CMA). The mean number of casein-specific IL-4- and IL-13-secreting T cells was higher in CMA than in non-CMA children (P = 0.009, 0.004, respectively). Moreover, it was inversely correlated with the cumulative dose of cow's milk tolerated (P = 0.003, 0.0009, respectively). ROC curve of combined IL-4 and IL-13 analysis showed an area under the curve of 0.98 (95% CI 0.90-1.06). For a cutoff of 10 IL-4- and 12 IL-13-secreting T cells, sensitivity and negative predictive value were 100%.

CONCLUSIONS

Enumeration of casein-specific IL-4- and IL-13-secreting T cells appears a promising tool to improve diagnosis and, if confirmed in larger studies, could permit less frequent use of the oral food challenge.

Allergen-specific responses of CD19(+)CD5(+)Foxp3(+) regulatory B cells (Bregs) and CD4(+)Foxp3(+) regulatory T cell (Tregs) in immune tolerance of cow milk allergy of late eczematous reactions

Foxp3-expressing cells among CD19(+)CD5(+) B cells were identified as regulatory B cells. Food allergy manifesting as late eczematous reactions is regarded as a non-IgE-mediated food allergy. The diagnosis for milk allergy manifesting as late eczematous reactions was made on the basis of the findings obtained from a double-blind placebo-controlled food challenge in patients with atopic dermatitis. Twelve patients with milk allergy and 12 patients who could tolerate milk were selected. On casein stimulation, the CD19(+)CD5(+)Foxp3(+) B cell (Breg) fraction in CD5(+) B cells decreased from 4.4±1.1% to 3.1±0.7% (P=0.047, n=12) in the milk allergy group and increased from 4.4±1.3% to 5.2±1.4% (P=0.001, n=10) in the milk-tolerant group. On the other hand, on allergen stimulation, the number of CD4(+)Foxp3(+) regulatory T cells (Tregs) in the milk allergy group and milk-tolerant group increased from 2.6±0.7% to 3.4±0.6% (P=0.014, n=9) and from 2.7±1.0% to 3.5±1.0% (P=0.038, n=10), respectively. In conclusion, allergen-specific responses of Bregs, rather than those of Tregs, seem to influence the immune responses (i.e., allergy or tolerance) to a food allergen.

Peripheral blood immune response elicited by beta-lactoglobulin in childhood cow's milk allergy

Several studies analyzing the immune responses in patients with cow's milk allergy (CMA) have used T-cell lines or T-cell clones that require prolonged in vitro cell culturing and may result in a switched cell phenotype and function. We investigated immune responses to beta-lactoglobulin (b-LG) in peripheral blood mononuclear cells after a short in vitro antigen stimulation in children with acute CMA (both IgE-mediated and non-IgE-mediated forms) and in those who outgrew an IgE-mediated CMA. Healthy controls were also investigated. Peripheral blood mononuclear cells were assayed for IL-13, IFN-γ, IL-4, and IL-10. Although b-LG induced a cytokine production and/or cell proliferation almost in all children, included healthy controls, differences were observed among the four groups. Children with IgE-mediated CMA had a marked Th2-response, with high IL-13 production and proliferation, but low IFN-γ; by contrast, children with non-IgE-mediated CMA produced no, or very low, IL-13 and cell proliferation. Children, who outgrew CMA, showed a shift to a Th1-response, with reduced IL-13 and increased IFN-γ. IL-10-responses were high in all groups, with the highest level in healthy children; by contrast, IL-4 was undetectable in all children. This study highlights the use of shortly stimulated peripheral blood cells to investigate the food-induced immune responses.

Allergen-specific T cell quantity in blood is higher in allergic compared to nonallergic individuals

Background

Allergen-specific IgE production is a hallmark of allergic asthma/rhinitis/eczema. Theoretically this could be due to a high number of allergen-specific B cells or allergen-specific T cells helping allergen-specific B cells differentiate into IgE-producing plasma cells. Here, we determined whether the number of allergen-specific B cells or T helper (Th) cells is higher in allergic individuals compared to nonallergic individuals.

Methods

A total of 52 allergic individuals and 32 nonallergic individuals were studied. The allergen-specific B and Th cells were enumerated by culturing CFSE-loaded blood mononuclear cells for 7-days with allergen (cat, Timothy or birch), and determining the number of proliferating B or Th cells (diluting CFSE) by flow cytometry. Allergen-specific IgE concentration was determined by fluorescent enzymoimmunoassay (FEIA).

Results

The quantities of proliferating Th cells but not proliferating B cells specific for cat, Timothy and birch were significantly higher in cat-, Timothy- and birch-allergic individuals compared to nonallergic individuals. The titer of allergen-specific IgE showed significant correlation with allergen-specific Th cells and not with allergen-specific B cells for all 3 allergens.

Conclusions

A high number of allergen-specific proliferating Th cells, but not proliferating B cells, may play a role in the pathogenesis of allergic asthma/rhinitis/eczema.

Diagnosis and Rationale for Action Against Cow's Milk Allergy (DRACMA): a summary report

The 2nd Milan Meeting on Adverse Reactions to Bovine Proteins was the venue for the presentation of the first consensus-based approach to the management of cow's milk allergy. It was also the first time that the Grading of Recommendations, Assessments, Development, and Evaluation approach for formulating guidelines and recommendations was applied to the field of food allergy. In this report we present the contributions in allergen science, epidemiology, natural history, evidence-based diagnosis, and therapy synthesized in the World Allergy Organization Diagnosis and Rationale for Action against Cow's Milk Allergy guidelines and presented during the meeting. A consensus emerged between discussants that cow's milk allergy management should reflect not only basic research but also a newer and better appraisal of the literature in the light of the values and preferences shared by patients and their caregivers in partnership. In the field of diagnosis, atopy patch testing and microarray technology have not yet evolved for use outside the research setting. With foreseeable breakthroughs (eg, immunotherapy and molecular diagnosis) in the offing, the step ahead in leadership can only stem from a worldwide organization implementing consensus-based clinical practice guidelines to diffuse and share clinical knowledge.

Clinical allergy to hazelnut and peanut: identification of T cell cross-reactive allergens

BACKGROUND

Peanut and tree nut allergies are life-threatening conditions for many affected individuals worldwide. Currently there is no cure. While co-allergy to peanut and tree nuts is a common clinical observation, and IgE cross-reactivity between peanut and tree nuts is reported, T cell cross-reactivity is poorly defined.

METHODS

Hazelnut-specific T cell lines were established using peripheral blood mononuclear cells from 5 subjects with co-allergy to hazelnut and peanut. These lines were stimulated with hazelnut and peanut extracts and purified major peanut allergens, Ara h 1 and Ara h 2. Proliferation was determined by (3)H-thymidine incorporation and secretion of key Th1 (IFN-γ) and Th2 (IL-5) cytokines analysed by ELISA.

RESULTS

Hazelnut-specific T cell lines from all 5 subjects proliferated upon stimulation with both hazelnut and peanut extracts and for 4 subjects, to Ara h 1 and/or Ara h 2. Proliferating cells were mainly CD4+ T cells and produced both IL-5 and IFN-γ in response to hazelnut and peanut stimulation. Mitogenicity of extracts and allergens was excluded by their lack of stimulation of house dust mite-specific T cells.

CONCLUSION

Our finding that hazelnut and peanut co-allergy is associated with cross-reactive T cell responses, driven partly by cross-reactivity to the major peanut allergens Ara h 1 and Ara h 2, points to future development of allergen immunotherapy by targeting cross-reactive T cells.

IgE-mediated facilitated antigen presentation underlies higher immune responses in peanut allergy

BACKGROUND

Peanut allergy poses significant healthcare problems, because its prevalence is increasing in many countries, and it is rarely outgrown. To explore the immunological mechanisms that underlie peanut allergy and tolerance, we compared the peanut-specific responses of peanut-allergic (PA) and nonallergic (NA) individuals.

METHODS

We measured peanut-specific peripheral blood mononuclear cells (PBMC) proliferation using tritiated thymidine. The frequency of peanut-specific T cells amongst PBMC was determined by carboxyfluorescein succinimidyl ester labelling. The role of IgE-dependent facilitated antigen presentation (FAP) in modulating proliferation was investigated by depleting IgE from plasma with anti-IgE-coated beads and then assessing PBMC proliferation in the presence of IgE-depleted or nondepleted plasma.

RESULTS

We found that peanut-specific PBMC proliferation is higher and peaks earlier in PA than in NA donors. We investigated the immunological mechanisms that could underlie these differences. We found that both PA and NA have memory responses to peanut, but the frequency of peanut-specific T cells is higher in PA than in NA. Facilitated antigen presentation could cause both the higher proliferation and precursor frequency in PA. Facilitated antigen presentation activity in vitro was confirmed by showing that IgE depletion decreases proliferation, while adding IgE back restores it.

CONCLUSION

Our results identify FAP as a mechanism that underlies higher responses to peanut in PA. In these individuals, high levels of peanut-specific IgE could furthermore maintain long-term allergic T-cell responses. We raise the question whether, in the future, therapies targeting IgE such as anti-IgE antibodies may be used to suppress these T-cell responses.

Immunologic features of infants with milk or egg allergy enrolled in an observational study (Consortium of Food Allergy Research) of food allergy

BACKGROUND

Immune features of infants with food allergy have not been delineated.

OBJECTIVES

We sought to explore the basic mechanisms responsible for food allergy and identify biomarkers, such as skin prick test (SPT) responses, food-specific IgE levels, and mononuclear cell responses, in a cohort of infants with likely milk/egg allergy at increased risk of peanut allergy.

METHODS

Infants aged 3 to 15 months were enrolled with a positive SPT response to milk or egg and either a corresponding convincing clinical history of allergy to milk or egg or moderate-to-severe atopic dermatitis. Infants with known peanut allergy were excluded.

RESULTS

Overall, 512 infants (67% male) were studied, with 308 (60%) having a history of a clinical reaction. Skin test responses, detectable food-specific IgE, or both revealed sensitization as follows: milk, 78%; egg, 89%; and peanut, 69%. SPT responses and food-specific IgE levels were discrepant for peanut (15% for IgE > or = 0.35 kU(A)/L and negative SPT response vs 8% for positive SPT response and IgE <0.35 kU(A)/L, P = .001). Mononuclear cell allergen stimulation screening for CD25, cytokine-inducible SH2-containing protein (CISH), forkhead box protein 3 (FOXP3), GATA3, IL10, IL4, IFNG, and T-box transcription factor (TBET) expression by using casein, egg white, and peanut revealed that only allergen-induced IL4 expression was significantly increased in those with clinical allergy to milk (compared with nonallergic subjects) and in those sensitized to peanut, despite the absence of an increase in GATA3 mRNA expression.

CONCLUSIONS

Infants with likely milk/egg allergy are at considerably high risk of having increased peanut-specific IgE levels (potential allergy). Peanut-specific serum IgE levels were a more sensitive indicator of sensitization than SPT responses. Allergen-specific IL4 expression might be a marker of allergic risk. Absence of an increase in GATA3 mRNA expression suggests that allergen-specific IL-4 might not be of T-cell origin.

T cell proliferation and cytokine responses to ovalbumin and ovomucoid detected in children with and without egg allergy

BACKGROUND

The specific T cell responses in egg allergy and resolution have not been fully elucidated.

OBJECTIVE

To characterize egg allergen-specific T cells of children with active and resolved egg allergy, in comparison with non-allergic controls.

METHOD

We studied children with active (n=35) or resolved (n=20) egg allergy determined by oral challenge, and non-allergic controls (n=15). Peripheral blood mononuclear cells were labelled with carboxyfluorescein succinimidyl ester (CFSE) and stimulated with ovalbumin (OVA), ovomucoid (OM) or tetanus toxoid. Flow cytometry was used to detect divided CD3+ CFSE(lo) cells that expressed intra-cytoplasmic IL-4 or IFN-gamma. The cell division index (CDI) was calculated as a measure of allergen-specific proliferation. Peanut-specific T cells of a subgroup of children who also had peanut allergy were also studied.

RESULTS

OVA-specific T cells were found in subjects with active (87%) or resolved (75%) egg allergy and in controls (67%), with a trend towards increased T cell proliferation in allergy. OM-induced weaker T cell responses than OVA, stimulating fewer responders (46% allergic, 50% resolved, 60% controls) and 10-fold less proliferation [CDI(OVA) 2.0 (median), 25.6 (maximum) vs. CDI(OM) 0.2 (median), 15.1 (maximum); P<0.01]. Both egg allergens induced significant IL-4+ (median 10%, range 1.4-58%) and IFN-gamma+ (median 28%, range 4.5-63%) cells in responders, including non-allergics. There were no significant differences in IFN-gamma+ or IL-4+ cells or in IFN-gamma/IL-4 ratios between groups. Peanut-specific T cell proliferation was significantly higher in peanut allergy [CDI(CPE) 16.5 (median), 24.8 (maximum)] compared with controls [CDI(CPE) 2.1 (median), 16.1 (maximum)] but cytokine profiles were not different. Tetanus-specific T cells were seen in 90% of the subjects, with no significant inter-group differences in responses.

CONCLUSION

Egg allergen-specific T cells are readily detected in all groups and not restricted to egg allergy. In contrast, peanut-specific proliferation was significantly higher in peanut allergy. This suggests that T cell responses in peanut and egg allergy may differ. We did not find T helper type 2-deviated cytokine responses in egg or peanut allergy.