Selective expansion of T cells expressing V beta 2 in peanut allergy

Nonimmunoglobulin e-mediated immune reactions to foods

: Adverse food reactions are abnormal responses to ingested foods. Reactions vary from immunologic to nonimmunologic immune reactions and can be either immunoglobulin E (IgE) mediated or non-IgE mediated. Food-induced IgE-mediated reactions range from localized urticaria to anaphylaxis and have been well studied. However, in comparison, there has been significantly less research into non-IgE-mediated food reactions. Non-IgE-mediated reactions can cause respiratory, gastrointestinal, and cutaneous symptoms. The most recent evidence suggests that these reactions are probably T-cell mediated as evidenced in lymphocyte proliferation assays. This review will explore the symptoms and testing methods of the most common non-IgE-mediated reactions.

The effect of specific immunotherapy on T-cell receptor repertoire in patients with allergy to house-dust mite

BACKGROUND

The precise mechanism of specific immunotherapy (SIT), long used for treating allergic diseases, remains undefined. SIT was shown to act by modifying the immune response of T lymphocytes to antigens. We examined the effect of SIT on the expression and use V-alpha, -beta, -gamma and -delta chains of T-cell receptors (TCR) in patients allergic to house-dust mite.

METHODS

Peripheral venous blood was taken for lymphocyte TCR analysis from 10 house-dust mite (HDM) allergic adults before initiating SIT and 6 months after initiating the treatment. Twelve similarly allergic patients without SIT served as controls. TCR chains were identified by fluorescence-activated cell sorter (FACS) using the following monoclonal antibodies: CD3, CD14, CD8, pan alpha-beta, pan gamma-delta, V-alpha2, V-alpha12.1, V-beta5a, V-beta5b, V-beta5c, V-beta8a, V-beta8b, V-beta3.1, V-beta13, V-beta12, V-beta6.7, V-delta1, V-delta2, V-gamma9, and V-gamma4.

RESULTS

Analyzed before and 6 months after SIT initiation, lymphocyte TCR showed significantly increased V-beta5b, V-beta12 and V-alpha12.1 values compared to controls (without significant changes in other markers).

CONCLUSIONS

SIT caused selective expansion of certain V-beta- and V-alpha-expressing T cells in patients allergic to HDM. Our results support the notion that the effect of SIT in patients with allergic rhinitis may be achieved by modifying the T lymphocyte response through the modulation of TCR usage.

Polymorphism in the STAT6 gene encodes risk for nut allergy

Nut allergy is an important and potentially life threatening food allergy with a prevalence of one in 150 children in the UK population. STAT6 (signal transducer and activator of transcription) is an important molecule in the induction and regulation of an allergic response, which maps to chromosome 12q in a region previously linked with total serum IgE concentration and atopy in different populations. We have examined the frequency of a single nucleotide polymorphism (SNP) in the 3'UTR region of STAT6 gene in 71 UK Caucasoid patients diagnosed with nut allergy and 45 atopic patients without nut allergy using PCR-RFLP and compared these with 184 UK healthy controls. The STAT6 G allele frequency was significantly increased in nut allergy patients compared with blood donor controls (P < 0.0001, OR = 2.9, 95% CI: 1.7-4.9), which was under a recessive model (GG vs GA+AA, P = 0.0001, OR = 3.2, 95% CI: 1.7-5.8) but not in atopic patients without nut allergy. The G allele was most frequent in the severe cases and GG homozygosity was associated with the increased risk of severe reaction (OR = 3.9, 95% CI: 1.9-8.3). We conclude that STAT6 3'UTR polymorphism is associated with susceptibility and severity in nut allergic patients in our population.

Vbeta18.1(+) and V(alpha)2.3(+) T-cell subsets are associated with house dust mite allergy in human subjects

BACKGROUND

The recognition of allergenic peptides by T cells through their T-cell receptor (TCR) represents a crucial step in the initiation of an allergen-specific immune response. In parallel to the superantigen-driven restricted expansion of Vbeta subsets in autoimmune and infectious diseases, reports in animals and human subjects have shown a similar capacity of classical antigens.

OBJECTIVE

The study was performed to analyze the V(alpha)/Vbeta expression in house dust mite (HDM) allergy.

METHODS

The TCR repertoire of 15 subjects with HDM allergy, 22 atopic subjects without HDM allergy, and 19 nonatopic individuals, members of 2 extended and 4 nuclear families, was determined. By using flow cytometry, the expression of 22 Vbeta and 3 V(alpha) elements was analyzed in vivo and after in vitro allergen stimulation.

RESULTS

In comparison with nonatopic and atopic individuals without HDM allergy, freshly isolated PBMCs of individuals with HDM allergy showed a significantly higher frequency of Vbeta18(+) and V(alpha)2.3(+) T cells. Although members of all 3 groups had a similar lymphocyte proliferation response after in vitro stimulation with Der p 1 or Der p 1 peptide(101-131), a significant expansion of Vbeta18(+) and V(alpha)2.3(+) T cells in vitro occurred only in individuals with HDM allergy. Moreover, the degree of expansion correlated with the levels of allergen-specific IgE antibodies. No expansion of Vbeta18(+) and V(alpha)2.3(+) was observed after mitogen stimulation with PHA, indicating allergen specificity of the response.

CONCLUSION

Our results strongly suggest restricted TCR V(alpha)/Vbeta gene use in HDM allergy and might be a step toward TCR-based immunotherapy.

Modification of T-cell receptor Vbeta repertoire in response to allergen stimulation in peanut allergy

BACKGROUND

Peanut is one of the most common foods causing allergic reactions and is the most common cause of fatal and near-fatal food-related anaphylaxis. Little is known of the immunologic mechanisms that underlie peanut allergy.

OBJECTIVES

In this study we examined clonality of the T-cell response (TCR) to peanut in MHC class II identical, peanut allergy-discordant sibling pairs.

METHODS

Four sibling pairs were investigated. The TCR repertoire was analyzed before and after in vitro stimulation of PBMCs with crude peanut or PHA, as control for general/nonspecific reactivity. Eighteen TCR-Vbeta families were examined by flow cytometry. Where significant differences in incidence of particular TCR-Vbeta families were observed, PCR familyspecific cDNA amplification and gene scanning were performed.

RESULTS

After stimulation with peanut, no selective expansion of any TCR-Vbeta subpopulation was observed with flow cytometry, in either the peanut-allergic or nonallergic siblings, with the exception of 1 peanut-allergic subject who demonstrated a significant increase of TCR-Vbeta11(+) cells (0.3%-5.9% of the total CD3(+) cells). However, gene scanning revealed predominant single-size PCR products for TCRBV11 in all peanut-allergic subjects after peanut stimulation. TCRBV11 polyclo-nality was observed in allergic and nonallergic subjects before peanut stimulation and in nonallergic subjects after peanut stimulation. In comparison, all subjects, before and after stimulation with peanut, showed polyclonality for TCRBV2.

CONCLUSIONS

Our results argue for clonal or oligoclonal TCRs to crude peanut and indicate that changes in the TCRBV11 subpopulation are restricted to peanut-allergic subjects after stimulation with crude peanut allergen.

The mucosal adhesion receptor alpha4beta7 integrin is selectively increased in lymphocytes stimulated with beta-lactoglobulin in children allergic to cow's milk

BACKGROUND

It has been shown in mice that the integrin alpha4beta7 directs the migration of memory T cells into the gut-associated lymphoid tissue. However, little is known about T-cell homing mechanisms in children with food allergies.

OBJECTIVE

We investigated the expression of this and other integrins in children with different manifestations of cow's milk allergy (urticaria, atopic dermatitis, and wheezing).

METHODS

PBMCs were stimulated with beta-lactoglobulin, 1 of the major allergenic proteins in cow's milk, and tetanus toxoid. Integrin expression was studied by flow cytometric analysis after 1 week of culture.

RESULTS

We found significantly higher expression of the alpha4beta7 integrin in cells from patients compared with control subjects with no allergies (P =. 005) when beta-lactoglobulin was used to stimulate the cells. alpha4beta7 integrin was also expressed at significantly higher levels in beta-lactoglobulin-stimulated cells than in tetanus toxoid-stimulated cells (P =.005). The alphaEbeta7 and the alpha4beta1 integrins were not upregulated by allergen stimulation. Most alpha4beta7 integrin-expressing cells were identified as CD4(+) T cells.

CONCLUSION

These results show that alpha4beta7 integrin expression after stimulation with beta-lactoglobulin correlates with the presumptive site of cow's milk sensitization (ie, the gut-associated lymphoid tissue but not with the site of symptoms of cow's milk allergy).

Peanut allergic subjects' peripheral blood mononuclear cell proliferative responses to crude peanut protein

BACKGROUND

Peanut allergy is characterized by a high frequency of severe and occasionally fatal reactions.

OBJECTIVE

To determine if there are features of the in vitro cellular response that may account for the observed severity of peanut allergy.

METHODS

Skin-prick testing (SPT), RAST assay of serum peanut-specific and total IgE and mixed peripheral blood mononuclear cells (PBMC) proliferative responses to crude peanut protein were measured in 44 peanut allergics with varying severity of clinical reactions. PBMC responses of 13 non-peanut allergic controls (six atopic) were also studied.

RESULTS

Subjects' PBMCs proliferated more than controls', even without stimulation. Subjects' PBMC proliferative responses did not correlate with clinical severity, SPT weal size or peanut-specific IgE levels. Controls' PBMCs did not respond to peanut. There was no correlation between PBMC response and time since last reaction to peanut. Subjects' PBMCs responded more than controls, to mitogen as well as allergen. Proliferation increased with increasing concentration of peanut protein (P < 0.0001).

CONCLUSION

PBMCs of peanut allergics demonstrate a dose-dependent response to peanut which does not correlate with clinical severity, SPT reaction or levels of peanut specific IgE. The response is antigen-specific. Peanut protein is not mitogenic and is not acting as a superantigen. While there are non-specific differences in the PBMC responses of peanut allergic individuals compared with atopic and non-atopic controls, these differences do not explain the unique severity of peanut allergy.

HLA class II DRB1, DQB1 and DPB1 genotypic associations with peanut allergy: evidence from a family-based and case-control study

BACKGROUND

Peanut is one of the most common foods provoking allergic reactions and is the most frequent cause of fatal and near-fatal food-induced anaphylaxis. However, as yet, little is known of the genetic and immunological mechanisms which underly peanut allergy.

OBJECTIVE

Based on findings in other allergic diseases, we have investigated whether particular human leucocyte antigen (HLA) class II genetic polymorphisms contribute to the development of peanut allergy.

METHODS

All individuals from 37 families each containing one or more peanut allergic individuals, plus nine unrelated patients (161 individuals in total, defined as the study group) were typed for the HLA class II DRB1, DQB1 and DPB1 loci, by PCR-based techniques. Genotype frequencies were compared with those found in 293 unrelated controls.

RESULTS

Four class II genotypes (DRB1*08 (13.7% vs 4.8%; Pc = 0.026), DRB1*08/12 tyr 16 (22.4% vs 8.2%; Pc = 0.021), DQB1*04 (12.2% vs 2.7%; Pc = 0.0026) and DPB1*0301 (49.1 vs 22.5%; Pc = 0.00062)) were present at a significantly higher frequency in the study group compared with controls. Three of these genotypes (DRB1*08 (18.0%; Pc = 0.027), DRB1*08/12 tyr16 (24.0%; Pc = 0.029) and DQB1*04 (16.7%; Pc = 0.0029)) were also significantly increased in peanut allergic individuals compared with controls. In addition, two genotypes (DPB1*0101 and 0201) were significantly decreased in frequency in the overall study group, but not specifically in peanut allergic individuals.

CONCLUSION

While other genetic factors may be important, results from this study indicate that HLA class II genetic polymorphism may play a role in determining susceptibility to peanut allergy.