Cell-surface expression of CD25, CD26, and CD30 by allergen-specific T cells is intrinsically different in cow's milk allergy

Current and future biomarkers in allergic asthma

Diagnosis early in life, sensitization, asthma endotypes, monitoring of disease and treatment progression are key motivations for the exploration of biomarkers for allergic rhinitis and allergic asthma. The number of genes related to allergic rhinitis and allergic asthma increases steadily; however, prognostic genes have not yet entered clinical application. We hypothesize that the combination of multiple genes may generate biomarkers with prognostic potential. The current review attempts to group more than 161 different potential biomarkers involved in respiratory inflammation to pave the way for future classifiers. The potential biomarkers are categorized into either epithelial or infiltrate-derived or mixed origin, epithelial biomarkers. Furthermore, surface markers were grouped into cell-type-specific categories. The current literature provides multiple biomarkers for potential asthma endotypes that are related to T-cell phenotypes such as Th1, Th2, Th9, Th17, Th22 and Tregs and their lead cytokines. Eosinophilic and neutrophilic asthma endotypes are also classified by epithelium-derived CCL-26 and osteopontin, respectively. There are currently about 20 epithelium-derived biomarkers exclusively derived from epithelium, which are likely to innovate biomarker panels as they are easy to sample. This article systematically reviews and categorizes genes and collects current evidence that may promote these biomarkers to become part of allergic rhinitis or allergic asthma classifiers with high prognostic value.

Lymphocyte surface molecules as immune activation biomarkers

Immunosuppression is mandatory after solid organ transplantation between HLA mismatched individuals. It is a lifelong therapy that needs to be closely monitored to avoid under- and over-immunosuppression. For many drugs, pharmacokinetic monitoring has been proven to be beneficial. However, the therapeutic ranges are statistically derived surrogate markers for the effects that cannot predict the individual response of single patients. Better tailored immunosuppression biomarkers are needed that indicate immune activation. T cells are critically involved in organ rejection, and the means to assess their activation state may be promising to individualize immunosuppressive therapies. Activated T cells can be monitored with flow cytometry based on surface molecules that are typically up regulated or with molecules that are cleaved off the cell surface. Among these molecules are the interleukin-2 receptor (CD25); transferrin receptor (CD71); the T cell co-stimulatory molecules CD28, CD69, and CD154 and sCD30, which is a member of the TNF-alpha family. The effect of immunosuppressive drugs on T cell activation can be recorded with indirect cell function assays or by directly monitoring activated T cells in whole blood. Soluble proteins can be measured with immunoassays. This review provides a summary of the experimental and clinical studies investigating the potential of surface molecules as a tool for immune monitoring. It critically discusses the obstacles and shortcomings from an analytical and diagnostic perspective that are currently preventing their use in multicenter trials and clinical routine monitoring of transplant patients.

The relative values of CD8+CD25+Foxp3brigh Treg cells correlate with selected lung function parameters in asthma

The study aimed to detect CD8(+)CD25(+)FoxP3(brigh) Tregs and investigate their possible association with selected lung function values. CD8(+)CD25(+)FoxP3(brigh) Tregs were detected by flow cytometry in the peripheral blood of 25 patients with severe asthma (SA), 25 patients with mild-to-moderate asthma (MA), and 25 age-matched healthy donors (NC). The percentages of CD8(+)CD25(+)FoxP3(brigh) Tregs of the patients with severe (3.4 ± 4.55), and mild-to-moderate asthma (7.5 ± 8.15), were markedly lower than those of controls (12.1 ± 13.2). The mean forced expiratory volume in 1 s (FEV1) % predicted value in severe asthma subpopulation was significantly lower (67.05 ± 15.98%) when compared with that of mild-to-moderate asthma subgroup (87.71 ± 16.12%). Interestingly, the percentages of CD8(+)CD25(+)FoxP3(brigh) Tregs correlate with mean peak expiratory flow (PEF)% predicted values in severe (r = 0.7, P <0.01) and mild-to-moderate (r = 0.73, P <0.01) asthma. In contrast, this parameter was positively correlated with FEV1% predicted values in the severe asthmatics only (r = 0.71, P <0.01). In summary, this study establishes a link between the percentage of CD8(+)CD25(+)FoxP3(brigh) Tregs and selected lung function parameters, suggesting that this parameter has potential as a marker for inflammation and airflow obstruction.

Expression of Th1, Th2, lymphocyte trafficking and activation markers on CD4+ T-cells of Hymenoptera allergic subjects and after venom immunotherapy

Systemic reactions to Hymenoptera stings can be fatal and represent a reduction in the quality of life. The immune mechanisms involved in venom allergic subjects are barely known. Nevertheless, a shift towards a Th1-type response with an increase in IFNγ levels has been observed after venom immunotherapy (VIT). There is currently no information available about the expression of markers on CD4+ T-cells or their involvement in venom allergy, nor following VIT. For this, we have studied the expression of Th1 and Th2-cell markers, homing receptors and activation markers on CD4+ T-cells of subjects who presented systemic allergic reactions, mainly to Polistes dominulus, and after receiving a 4-month conventional VIT protocol. The markers studied were: CD26 (Th1), CD30 (Th2), CXCR4, CXCR3 (Th1), CCR4 (Th2), CD154 (CD40L), CD152 (CTLA-A), and ICOS. We also determined the IL-4 (Th2) and IFNγ (Th1) intracellular cytokine levels in T-cells and carried out a basophil activation test (BAT). Comparing venom allergic subjects with non-allergic healthy controls, we have found up-regulation of CD26, CXCR4, CXCR3, CD154 and ICOS. Conversely, a down-regulation of CD30, CD154 and CD152 occurred upon immune intervention, whereas the remaining markers were not affected. Equally, VIT has been shown to be effective, as evidenced by the decrease of basophil degranulation and increase of IFNγ levels in T-cells after the fourth month of treatment. These new findings highlight the possible application of these surface molecules as markers to distinguish between symptomatic and asymptomatic subjects sensitized to Hymenoptera venom, as well as revealing information about the immune changes associated with VIT.

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.

Dysregulated Th1 and Th2 responses in food-allergic children--does elimination diet contribute to the dysregulation?

Infants with eczema and sensitization to foods are recommended skin care and, if food allergy is proven, an elimination diet. Although most of these children tolerate foods before 3 yr of age, some children experience prolonged food allergy. To our knowledge, no prospective study has investigated the cytokine profile in food-sensitized eczematous children with prolonged food intolerance. The aim of the study was to prospectively investigate the development of cytokine production induced by food allergen in food-sensitized eczematous children who, at 4(1/2) yr of age, were allergic or tolerant to egg or milk. Twenty-one eczematous infants, [age 5 (3-10) months; median and range], sensitized to egg and/or milk were included, put on elimination diet and followed prospectively. At 4(1/2) yr of age, the children were defined as tolerant or allergic to egg and/or milk based on open or double-blind placebo-controlled food challenges. Peripheral blood mononuclear cells (PBMC) were isolated from the children on inclusion, after 6 wk of elimination diet, and at 3 and 4(1/2) yr of age. Ovalbumin, beta-lactoglobulin and tetanus toxoid-induced IL-4, -5, -10, -13 and IFN-gamma production from PBMC were analyzed with enzyme-linked immunosorbent assay. The IFN-gamma and IL-5 secretion induced by food allergen at 4(1/2) yr was higher in cell cultures from children who were allergic to egg or milk than in tolerant children. In food-allergic children, the levels of IFN-gamma and IL-5 were higher at 4(1/2) yr compared with inclusion levels, but this increase was generally not observed in the tolerant children who consumed milk and egg. In conclusion, immune cells from food-allergic children on an elimination diet respond with up-regulated T helper 1 and T helper 2 cytokine secretion induced by food allergen. We hypothesize that allergen elimination may influence the regulatory mechanisms maintaining balanced immune responses to innocuous food antigens.

T cell responses to major peanut allergens in children with and without peanut allergy

BACKGROUND

T cell responses involved in peanut allergy are poorly understood.

OBJECTIVE

To investigate T cell responses towards major peanut allergens in peanut-allergic (PA) subjects compared with peanut-sensitized (PS) non-allergic children and non-atopic (NA) controls.

METHODS

Eighteen PA children, seven non-allergic PS children and 11 NA adults were included. Peripheral blood mononuclear cells were stimulated with a crude peanut extract (CPE). Short-term T cell lines were generated and subsequently stimulated with CPE and purified Ara h 1, Ara h 2, Ara h 3 and Ara h 6. The proliferation and production of IL-13, IFN-gamma, IL-10 and TNF-alpha were analysed.

RESULTS

Proliferation to CPE and major allergens was enhanced in PA subjects. The primary response to CPE was comparable with PS subjects, with increased production of IL-13 and IFN-gamma compared with NA. Production of IL-10 was not observed. In short-term T cell lines, the response to CPE was stronger in PA than in PS and NA subjects. Only PA children had a detectable response to major peanut allergens, characterized by IL-13 production. The response was the highest after Ara h 3 stimulation, and the lowest after Ara h 2 stimulation. No significant correlation was observed between peanut-specific IgE levels and T cell responses to CPE.

CONCLUSION

T cell responses to CPE in PA and PS children were characterized by Th1 and Th2 cytokines. Only PA children showed enhanced Th2 responses to Ara h 1, Ara h 3 and Ara h 6.

On the origin of serum CD26 and its altered concentration in cancer patients

Dipeptidyl peptidase IV (DPP-IV), assigned to the CD26 cluster, is expressed on epithelial cells and lymphocytes and is a multifunctional or pleiotropic protein. Its peptidase activity causes degradation of many biologically active peptides, e.g. some incretins secreted by the enteroendocrine system. DPP-IV has, therefore, become a novel therapeutic target for inhibitors that extend endogenously produced insulin half-life in diabetics, and several reviews have appeared in recent months concerning the clinical significance of CD26/DPP-IV. Biological fluids contain relatively high levels of soluble CD26 (sCD26). The physiological role of sCD26 and its relation, if any, to CD26 functions, remain poorly understood because whether the process for CD26 secretion and/or shedding from cell membranes is regulated or not is not known. Liver epithelium and lymphocytes are often cited as the most likely source of sCD26. It is important to establish which tissue or organ is the protein source as well as the circumstances that can provoke an abnormal presence/absence or altered levels in many diseases including cancer, so that sCD26 can be validated as a clinical marker or a therapeutic target. For example, we have previously reported low levels of sCD26 in the blood of colorectal cancer patients, which indicated the potential usefulness of the protein as a biomarker for this cancer in early diagnosis, monitoring and prognosis. Through this review, we envisage a role for sCD26 and the alteration of normal peptidase capacity (in clipping enteroendocrine or other peptides) in the complex crosstalk between the lymphoid lineage and, at least, some malignant tumours.

Sensitization to human milk

BACKGROUND

Allergy to milk is one of the earliest manifestations of IgE-mediated allergies and affects about 2.5% of newborn children. Several reports indicate that milk-allergic patients may be sensitized also to human milk proteins.

OBJECTIVE

To analyse the specificity and possible biological relevance of IgE reactivity to human milk antigens in milk-allergic patients.

METHODS

The specificity of IgE reactivity to cow's milk and human milk antigens was analysed with sera from milk-allergic children and adults by IgE immunoblotting. IgE cross-reactivity between milk antigens was studied by immunoblot inhibition experiments. That IgE reactivity to human milk antigens is not due to alloreactivity or due to the transmission of foreign antigens into mother's milk was demonstrated through the analysis of milk samples from genetically unrelated mothers before and after intake of dietary milk products. The biological relevance of IgE reactivity to human milk was confirmed by skin testing. Results IgE antibodies to human milk were found in more than 80% of the tested milk-allergic patients. Cross-reactive IgE-reactive human antigens such as alpha-lactalbumin and non-cross-reactive human milk antigens were identified. Immediate-type skin reactions could be elicited with human milk samples in patients with IgE reactivity to human milk.

CONCLUSION

IgE reactivity to human milk in milk-allergic patients can be due to cross- sensitization and genuine sensitization to human milk and may cause allergic symptoms. IgE-mediated sensitization to human milk is common in milk-allergic patients and may require diagnostic testing and monitoring.

Role of human leucocyte antigen DQ in the presentation of T cell epitopes in the major cow's milk allergen alphas1-casein

BACKGROUND

Little is known about the association between human leucocyte antigen (HLA) and cow's milk allergy (CMA). The aim of the present study was to determine the HLA restriction of T cell clones (TCCs) specific to alphas1-casein, the most abundant milk protein, and to study possible HLA class II allele associations with CMA.

METHODS

alphas1-Casein-specific TCCs were derived from 6 children with CMA, 9 atopic children without CMA and 5 non-atopic children. T cell epitope specificity was defined by stimulation with overlapping peptides, spanning the alphas1-casein molecule. HLA restriction was determined in proliferation assays using antibodies blocking either HLA-DP, HLA-DQ or HLA-DR. HLA genotyping was performed in 32 subjects with CMA, 23 atopic and 22 non-atopic individuals.

RESULTS

Ten TCCs were restricted to HLA-DQ, 6 TCCs to HLA-DR and 4 TCCs to HLA-DP. The sequence in alphas1-casein that was most immunogenic to T cells from children with CMA contained T cell epitopes restricted to DQB1*0201, DPB1*0401 and DRB1*1501. The DQB1*0501 allele frequency was lower in children with CMA than in non-atopic children, but this difference could not be confirmed in an additional group of subjects with and without CMA.

CONCLUSIONS

HLA-DQ plays a substantial role in the presentation of T cell epitopes in alphas1-casein. However, HLA class II allele frequencies do not show major differences between cow's milk allergic, atopic and non-atopic subjects. T cell epitopes in the most immunogenic region are presented by various abundantly present HLA genotypes. Therefore, this sequence may be a suitable target for peptide immunotherapy.

T lymphocytes and food allergy

Food allergy is a hypersensitivity reaction to normally harmless substances and involves humoral immune responses, mediated by immunoglobulin (IgE) synthesized by B lymphocytes, and cellular immune responses mediated by T lymphocytes. An IgE-mediated mechanism leads to clinical symptoms occurring immediately after food ingestion, e. g., "the oral allergy syndrome". For delayed reactions involving the gastrointestinal tract or the skin, the underlying immune mechanisms are less clear. In order to elucidate the cellular response to food allergens, human allergen-specific T cell cultures generated in vitro represent helpful tools. The majority of food allergen-specific CD4(+) T lymphocytes isolated from food-allergic individuals was found to synthesize high levels of IL-4 and IL-13, two cytokines required for initiation of IgE synthesis. Due to selective homing profiles, food-specific T cells seem also to be involved in defining the target organ of the allergic inflammation. Recent data provide evidence that in addition to IgE-mediated inflammation, food allergen-specific T lymphocytes may also cause inflammatory responses independently of IgE-mediated mechanisms.

Expression and a role of CD30 in regulation of T-cell activity

CD30 receptor has been known for almost 20 years, but its expression and activity are still the subject of many investigations. Its expression was found in different malignancies, and most of the studies regarding CD30 focus on its role in lymphomas. The progress that has already been made in this field is reflected in implementation of CD30 as a target for immunotoxin, which has been tested in phase I study in treating Hodgkin lymphoma. CD30 is present also on normal, activated T cells of all cytokine profiles. However, increased density of CD30 and CD30-mediated Th2 cytokine production provide evidence of its role in determining the activity of T cells toward synthesis of cytokines and involvement in reactions of Th2 characteristics. Pleiotropic signaling mediated by CD30 does not implicate this receptor just as a cytokine costimulator; it proves to be important in several different activities of T cells.

The T lymphocyte in food-allergy disorders

PURPOSE OF REVIEW

While much attention is focused upon the role of IgE antibodies in food-allergy disorders, the T cell remains central to all forms, both IgE and non-IgE-mediated, of food-hypersensitivity responses. This review considers the central role of the T cell in this group of disorders and provides a comprehensive overview of recent studies that elucidate our understanding of the mechanisms involved in the pathogenesis of food allergy in regard to the role of the T cell.

RECENT FINDINGS

Recent studies have defined a dynamic process involving T cell homing receptors (e.g. cutaneous lymphocyte antigen) and activation markers in food-hypersensitivity disorders. Modulation of the T-cell responses occurs through the recognition of dominant allergenic epitopes, the elaboration of regulatory cytokines (e.g. transforming growth factor-beta, IL-4, IL-5, tumor necrosis factor-alpha) and the influence of immunomodulatory microbial and environmental agents. The resulting disorders reflect T-cell dysregulation.

SUMMARY

Significant recent advances in our understanding of the role of the T cell in food hypersensitivity have been made and will probably contribute to improved diagnostic and treatment methods in the near future.

Early origins of allergic disease: a review of processes and influences during early immune development

PURPOSE OF REVIEW

With the disturbing increase in allergic disease, there is a pressing need to determine the causes, pathogenesis and safe avenues for disease prevention. Although events in early life appear important, no causal pathways have been identified. This review examines new developments in the area of foetal and early postnatal immune maturation. It secondly addresses early predisposing influences and protective factors that may have a future role in allergy prevention.

RECENT FINDINGS

New developments in the understanding of the ontogeny of allergen-specific immune responses in atopic infants are discussed, including the role of early type 1 and 2 immune responses, and how these are influenced by perinatal antigen presenting cell and T-cell immaturity. The controversial role of early dietary exposures including breastfeeding, food allergens, hydrolyzed formulae and other dietary factors including omega-3 fatty acids are discussed in the context of the most recent literature. Equally contentious, the role of early house dust and pet allergen exposure is discussed in light of new epidemiological studies and disappointing early results of multicentre allergen avoidance studies. Finally, a number of studies in animals and humans suggest that bacterial products can influence early immune development, providing a new potential therapeutic avenue for disease treatment and prevention.

SUMMARY

Complex multifactorial genetic and environmental interactions make research in this area difficult and apparent associations with allergic disease may not be causal in nature. Many current targets for prevention, such as early allergen exposure and infant feeding practices, are proving to be ineffective and may not be directly implicated in rising rates of disease.

Advances in anaphylaxis and hypersensitivity reactions to foods, drugs, and insect venom

This review highlights some of the research advances in anaphylaxis and hypersensitivity reactions to foods, drugs, and insect venom that were reported primarily in this Journal from 2001 to 2002. Among the topics highlighted: Epinephrine injected intramuscularly into the thigh provides the most efficient absorption profile for adults and children; determination of serum IgE antibody-specific food allergen concentrations and atopy patch tests with foods show promise for enhanced diagnostic accuracy; numerous food allergens are now characterized on the molecular level, allowing for improved diagnostic and treatment modalities; the complex immunologic mechanisms underlying drug hypersensitivity reactions are being elucidated; venom immunotherapy improves quality of life for sufferers, and increased venom immunotherapy doses are useful in recalcitrant cases.

Revisiting the "hygiene hypothesis" in gastrointestinal allergy

The "hygiene hypothesis" in its original form hypothesized that infection in early childhood acquired through unhygienic contact with siblings or the mother may prevent the development of allergic disease. Several recent epidemiologic surveys showing an inverse relationship between the frequency of infectious disease and the incidence of allergic diseases lend support to this hypothesis. Allergen sensitization of the immune system can occur early in utero against a background of neonatal commitment to a Th2 immune response involving the production of Th2 cytokines (eg, interleukin (IL)-4, IL-5, IL-13) that are the principal mediators of allergic inflammation. Continued allergen exposure is associated with predominantly CD4+ Th2 cell proliferation but does not exclude a minor Th1 allergen-specific subpopulation that can be further expanded nonspecifically and polyclonally by microbial superantigens or as bystanders, by interferon-gamma (IFN-gamma) and IL-2 released from Th1 effectors responding to antigens associated with infectious pathogens. Th1 cytokines can also subvert allergen-specific Th2 lymphocytes to become allergen-specific Th1 cells-a process reminiscent of the increased tendency of the maturing immune system of growing adults to mount a Th1 response to some environmental and dietary antigens. Unlike Th2 cytokines, IFN-gamma and IL-2 inhibit B-cell production of IgE and, hence, delimit the capacity of mast cells to degranulate and release allergenic mediators. The ability of infectious agents through their danger signals to initiate a Th1 response that deviates the Th2 allergenic bias is the basis of the hygiene hypothesis.