HLA-DR and HLA-DP genotypes and immunoglobulin E responses to common major allergens

AllergoOncology: Biomarkers and refined classification for research in the allergy and glioma nexus-A joint EAACI-EANO position paper

Epidemiological studies have explored the relationship between allergic diseases and cancer risk or prognosis in AllergoOncology. Some studies suggest an inverse association, but uncertainties remain, including in IgE-mediated diseases and glioma. Allergic disease stems from a Th2-biased immune response to allergens in predisposed atopic individuals. Allergic disorders vary in phenotype, genotype and endotype, affecting their pathophysiology. Beyond clinical manifestation and commonly used clinical markers, there is ongoing research to identify novel biomarkers for allergy diagnosis, monitoring, severity assessment and treatment. Gliomas, the most common and diverse brain tumours, have in parallel undergone changes in classification over time, with specific molecular biomarkers defining glioma subtypes. Gliomas exhibit a complex tumour-immune interphase and distinct immune microenvironment features. Immunotherapy and targeted therapy hold promise for primary brain tumour treatment, but require more specific and effective approaches. Animal studies indicate allergic airway inflammation may delay glioma progression. This collaborative European Academy of Allergy and Clinical Immunology (EAACI) and European Association of Neuro-Oncology (EANO) Position Paper summarizes recent advances and emerging biomarkers for refined allergy and adult-type diffuse glioma classification to inform future epidemiological and clinical studies. Future research is needed to enhance our understanding of immune-glioma interactions to ultimately improve patient prognosis and survival.

Associations between specific IgE sensitization to 26 respiratory allergen molecules and HLA class II alleles in the EGEA cohort

BACKGROUND

Allergy, the most frequent immune disorder affecting 30% of the world's population, is the consequence of immunoglobin E (IgE) sensitization to allergens. Among the genetic factors suspected to be involved in allergy, the HLA class-II genomic region is a strong candidate.

OBJECTIVE

To assess the association between HLA class-II alleles and specific IgE (sIgE) sensitization to a large number of respiratory allergen molecules.

METHODS

The analysis relied on 927 participants of the EGEA cohort, including 497 asthmatics. The study focuses on 26 aeroallergens recognized by sIgE in at least 5% of the study population (determined with the MEDALL chip with sIgE ≥ 0.3 ISU) and 23 imputed HLA class-II alleles. For each sIgE sensitization and HLA class-II allele, we fitted a logistic regression model accounting for familial dependence and adjusted for gender, age, and genetic principal components. p-values were corrected for multiple comparisons (False Discovery Rate).

RESULTS

Most of the 19 statistically significant associations observed regard pollen allergens (mugwort Art v 1, olive tree Ole e 1, timothy grass Phl p 2, Phl p 5 and plantain Pla l 1), three were mold allergen (Alternaria Alt a 1), and a single one regards house dust mite allergen (Der p 7). No association was observed with pet allergens. The strongest associations were found with mugwort Art v 1 (OR = 5.42 (95%CI, 3.30; 8.88), 4.14 (2.65; 6.47), 3.16 (1.88; 5.31) with DQB1*05:01, DQA1*01:01 and DRB1*01:01, respectively).

CONCLUSION

Our results support the important role of HLA class-II alleles as immune response genes predisposing their carriers for sensitization to various major pollen allergens.

Genetic restriction of antigen-presentation dictates allergic sensitization and disease in humanized mice

BACKGROUND

Immunoglobulin(Ig)E-associated allergies result from misguided immune responses against innocuous antigens. CD4+ T lymphocytes are critical for initiating and perpetuating that process, yet the crucial factors determining whether an individual becomes sensitized towards a given allergen remain largely unknown.

OBJECTIVE

To determine the key factors for sensitization and allergy towards a given allergen.

METHODS

We here created a novel human T cell receptor(TCR) and human leucocyte antigen (HLA)-DR1 (TCR-DR1) transgenic mouse model of asthma, based on the human-relevant major mugwort (Artemisia vulgaris) pollen allergen Art v 1 to examine the critical factors for sensitization and allergy upon natural allergen exposure via the airways in the absence of systemic priming and adjuvants.

RESULTS

Acute allergen exposure led to IgE-independent airway hyperreactivity (AHR) and T helper(Th)2-prone lung inflammation in TCR-DR1, but not DR1, TCR or wildtype (WT) control mice, that was alleviated by prophylactic interleukin(IL)-2-αIL-2 mAb complex-induced expansion of Tregs. Chronic allergen exposure sensitized one third of single DR1 transgenic mice, however, without impacting on lung function. Similar treatment led to AHR and Th2-driven lung pathology in >90% of TCR-DR1 mice. Prophylactic and therapeutic expansion of Tregs with IL-2-αIL-2 mAb complexes blocked the generation and boosting of allergen-specific IgE associated with chronic allergen exposure.

CONCLUSIONS

We identify genetic restriction of allergen presentation as primary factor dictating allergic sensitization and disease against the major pollen allergen from the weed mugwort, which frequently causes sensitization and disease in humans. Furthermore, we demonstrate the importance of the balance between allergen-specific T effector and Treg cells for modulating allergic immune responses.

GWAS of self-reported mosquito bite size, itch intensity and attractiveness to mosquitoes implicates immune-related predisposition loci

Understanding the interaction between humans and mosquitoes is a critical area of study due to the phenomenal burdens on public health from mosquito-transmitted diseases. In this study, we conducted the first genome-wide association studies (GWAS) of self-reported mosquito bite reaction size (n = 84,724), itchiness caused by bites (n = 69,057), and perceived attractiveness to mosquitoes (n = 16,576). In total, 15 independent significant (P < 5×10⁻⁸) associations were identified. These loci were enriched for immunity-related genes that are involved in multiple cytokine signalling pathways. We also detected suggestive enrichment of these loci in enhancer regions that are active in stimulated T-cells, as well as within loci previously identified as controlling central memory T-cell levels. Egger regression analysis between the traits suggests that perception of itchiness and attractiveness to mosquitoes is driven, at least in part, by the genetic determinants of bite reaction size.

Our findings illustrate the complex genetic and immunological landscapes underpinning human interactions with mosquitoes.

International consensus (ICON) on: clinical consequences of mite hypersensitivity, a global problem

Since mite allergens are the most relevant inducers of allergic diseases worldwide, resulting in significant morbidity and increased burden on health services, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), formed by the American Academy of Allergy, Asthma and Immunology (AAAAI), the American College of Allergy, Asthma and Immunology (ACAAI), the European Academy of Allergy and Clinical Immunology (EAACI), and the World Allergy Organization (WAO), has proposed to issue an International Consensus (ICON) on the clinical consequences of mite hypersensitivity. The objectives of this document are to highlight aspects of mite biology that are clinically relevant, to update the current knowledge on mite allergens, routes of sensitization, the genetics of IgE responses to mites, the epidemiologic aspects of mite hypersensitivity, the clinical pictures induced by mites, the diagnosis, specific immunotherapeutic approaches, and prevention.

Association between HLA genes and dust mite sensitivity in a Brazilian population

BACKGROUND

Type I hypersensitivity, also known as IgE-mediated allergy, is a complex, multifactorial condition whose onset and severity are influenced by both genetic and environmental factors. Mite allergens stimulate the production of humoral response (IgE), especially in children, which is closely involved in atopic asthma and rhinitis.

OBJECTIVE

This study aimed to investigate the association between HLA class I (-A, -B, and -C), and HLA class II (-DRB1) genes in individuals sensitive to dust mites (Dermatophagoides farinae, Dermatophagoides pteronyssinus, or Blomia tropicalis) and mite-insensitive controls.

METHODS

396 participants were grouped as mite-sensitive and mite-insensitive according to immediate hypersensitivity as determined by skin-prick tests, and to HLA genotyping by polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO).

RESULTS

After chi-square heterogeneity testing no significant differences were observed in HLA-A, B, and C genes, except for the HLA-DRB1 locus, which, showed a negative association for DRB1∗04, between mite-sensitive and mite-insensitive individuals. In high resolution, DRB1∗04:11 allele was significantly different from all other results (P=0.0042, OR=0.26, and 95%CI=0.09-0.70). The analysis stratified by etiologic agent confirmed these associations.

CONCLUSION

Our results suggest a possible association between HLA-DRB1 genes and hypersensitivity to dust mites.

HLA and asthma phenotypes/endotypes: a review

Asthma is a complex chronic inflammatory disease of the airways caused by the interaction of genetic susceptibility with environmental influences. Genome-wide association studies (GWAS) represent the most powerful approach for asthma, that have identified several genes (e.g., IL18R1, IL33, SMAD3, ORMDL3, HLA-DQ and IL2RB loci). HLA super-locus is a genomic region in the chromosomal position 6p21. Since no gene can be considered as an asthma gene, able to reflect the complex etiology and the heterogeneity of the disease the terms 'phenotype' and more recently 'endotype' have been used. This review, according to literature availability, focuses on the relationship between human leukocyte antigens (HLA) region specifically the HLA class II genes and different asthma phenotypes/endotypes, such as allergic asthma/Th2 associated, occupational and aspirin-sensitive asthma. The most common HLA haplotypes in the different asthma phenotypes are HLA-DRB1in allergic asthma, HLA-DQB1in occupational asthma and HLA-DPB1 in aspirin-sensitive asthma. However, it is difficult to study the role of class II genes in vivo because of the heterogeneity of human population, the complexity of MHC, and the strong linkage disequilibrium among different class II genes. Despite the variation and the inconsistency of the HLA haplotypes and alleles in different types of asthma, the association between HLA class II genes and asthma has been demonstrated in the majority of studies.

A genome-wide association meta-analysis of self-reported allergy identifies shared and allergy-specific susceptibility loci

Allergic disease is very common and carries substantial public-health burdens. We conducted a meta-analysis of genome-wide associations with self-reported cat, dust-mite and pollen allergies in 53,862 individuals. We used generalized estimating equations to model shared and allergy-specific genetic effects. We identified 16 shared susceptibility loci with association P<5×10(-8), including 8 loci previously associated with asthma, as well as 4p14 near TLR1, TLR6 and TLR10 (rs2101521, P=5.3×10(-21)); 6p21.33 near HLA-C and MICA (rs9266772, P=3.2×10(-12)); 5p13.1 near PTGER4 (rs7720838, P=8.2×10(-11)); 2q33.1 in PLCL1 (rs10497813, P=6.1×10(-10)), 3q28 in LPP (rs9860547, P=1.2×10(-9)); 20q13.2 in NFATC2 (rs6021270, P=6.9×10(-9)), 4q27 in ADAD1 (rs17388568, P=3.9×10(-8)); and 14q21.1 near FOXA1 and TTC6 (rs1998359, P=4.8×10(-8)). We identified one locus with substantial evidence of differences in effects across allergies at 6p21.32 in the class II human leukocyte antigen (HLA) region (rs17533090, P=1.7×10(-12)), which was strongly associated with cat allergy. Our study sheds new light on the shared etiology of immune and autoimmune disease.

Influence of asthma epidemiology on the risk for other diseases

Asthma is a multifactorial chronic disease affecting a significant proportion of people in the United States and worldwide. Numerous laboratory and epidemiological studies have attempted to understand the etiology and underlying mechanisms of asthma and to identify effective therapies. However, the impact of asthma on the risk for other diseases has drawn little attention. This paper discusses the potential effects of asthma as a risk factor for other diseases, explores the potential mechanisms, and reviews the implications of the findings to clinical practice, public health, and research.

HLA-DR polymorphism modulates response to house dust mites in a transgenic mouse model of airway inflammation

We and others have reported that HLA-DRB1*03 is associated with childhood asthma. To extend this observation and to prove this association, we sensitized and challenged either HLA-DR2 (HLA-DRB1*1502) or HLA-DR3 (HLA-DRB1*0301) transgenic mice with house-dust mite extract. Inflammatory cell counts and cytokine levels in the bronchoalveolar lavage (BAL) fluid between HLA-DR3 and DR2 mice were compared. HLA-DR3 transgenic mice had significantly elevated eosinophil counts, Interleukin-4 and Interleukin-13 levels in the BAL fluid but not interferron gamma-γ. Thus, our study suggests that HLA-DRB1*0301 plays an important role in mounting a Th2-predominant immune response to house dust mite and Th2-type inflammation in the lung.

Interaction of allergens, major histocompatibility complex molecules, and T cell receptors: a 'ménage à trois' that opens new avenues for therapeutic intervention in type I allergy

T cells are major players in the initiation and perpetuation of the allergic immune response. In this review, we summarize the current knowledge on allergen recognition by T lymphocytes and address the components of the trimeric recognition complex: T cell receptors, major histocompatibility complex molecules, and allergen-derived peptides. Furthermore, possible implications of this scientific background for future therapeutic developments are discussed.

Genetic impact of a butyrophilin-like 2 (BTNL2) gene variation on specific IgE responsiveness to Dermatophagoides farinae (Der f) in Japanese

BACKGROUND

Dermatophagoides farinae (Der f) is one of the most frequently implicated allergens in several allergic diseases. Several genome-wide screens have identified a linkage between chromosome 6p21 and mite-specific IgE responsiveness. Butyrophilin-like 2 (BTNL2) is a member of the immunoglobulin superfamily and, on the basis of its homology to B7-1, has been implicated as a costimulatory molecule involved in T-cell activation. BTNL2 resides in the HLA region on chromosome 6p21, and significant associations between BTNL2 gene polymorphisms and several inflammatory diseases have been reported.

OBJECTIVE

The aim of this study was to examine whether BTNL2 gene polymorphisms are associated with specific IgE responses to Der f.

METHODS

Three single nucleotide polymorphisms (SNPs), including 2 coding SNPs and 1 intron SNP, were studied. One of the coding SNPs was the rs2076530 A > G, which has a functional consequence. A total of 863 unrelated Japanese subjects (447 positive and 416 negative for IgE to Der f) were recruited for a case-control study.

RESULTS

Controlling for gender, age, smoking, and the presence of asthma, multiple logistic regression analyses showed that homozygosity of the rs2076530 A allele, which has been reported to be a risk allele for sarcoidosis, was associated with a risk of sensitization towards Der f (Odds ratio; 1.55, p = 0.0060).

CONCLUSIONS

Although an association which may be due to the linkage disequilibrium with other genes in 6p21 needs to be ruled out, the present findings suggest that the BTNL2 gene might be one of the candidate genes that is responsible for the pathogenesis of Der f-specific IgE responsiveness.

Characterization of HLA class II/peptide-TCR interactions of the immunodominant T cell epitope in Art v 1, the major mugwort pollen allergen

More than 95% of mugwort pollen-allergic individuals are sensitized to Art v 1, the major allergen in mugwort pollen. Interestingly, the CD4 T cell response to Art v 1 involves only one single immunodominant peptide, Art v 1(25-36) (KCIEWEKAQHGA), and is highly associated with the expression of HLA-DR1. Therefore, we investigated the molecular basis of this unusual immunodominance among allergens. Using artificial APC expressing exclusively HLA-DRB1*0101 and HLA-DRA*0101, we formally showed that DR1 acts as restriction element for Art v 1(25-36)-specific T cell responses. Further assessment of binding of Art v 1(25-36) to artificial HLA-DR molecules revealed that its affinity was high for HLA-DR1. Amino acid I27 was identified as anchor residue interacting with DR molecules in pocket P1. Additionally, Art v 1(25-36) bound with high affinity to HLA-DRB1*0301 and *0401, moderately to HLA-DRB1*1301 and HLA-DRB5*0101, and weakly to HLA-DRB1*1101 and *1501. T cell activation was also inducible by Art v 1(25-36)-loaded, APC-expressing HLA molecules other than DR1, indicating degeneracy of peptide binding and promiscuity of TCR recognition. Specific binding of HLA-DRB1*0101 tetramers containing Art v 1(19-36) allowed the identification of Art v 1(25-36)-specific T cells by flow cytometry. In summary, the immunodominance of Art v 1(25-36) relies on its affinity to DR1, but is not dictated by it. Future investigations at the molecular HLA/peptide/TCR and cellular level using mugwort pollen allergy as a disease model may allow new insights into tolerance and pathomechanisms operative in type I allergy, which may instigate new, T cell-directed strategies in specific immunotherapy.

The genetic and environmental basis of atopic diseases

The prevalence of atopic diseases has increased abruptly in recent years in most Westernized societies, making the question why this happened the topic of a heated debate. The best paradigm available to date to explain this steep rise, the 'hygiene hypothesis', supports that it is the excess 'cleanliness' of our environments that has led to the decline in the number of infectious stimuli that are necessary for the proper development of our immune system. Recent findings support that it is the combined effect that not only pathogenic, but also non-pathogenic microorganisms, and even their structural components,can exert on the immune system that deters from the development of atopic responses. Adding to these results are intriguing new findings on the effect different gene polymorphisms can have on an individual's predisposition to allergic diseases. The most important linkages produced, to date, include those among the genes for IL-4, IL-13, HLA-DRB, TNF, LTA,FCER1B, IL-4RA, ADAM33, TCR alpha/delta, PHF11, GPRA, TIM, p40, CD14, DPP10, T-bet, GATA-3, and FOXP3 and allergic disorders. The two parallel research efforts, epidemiologic and genetic, are only recently starting to converge,producing fascinating results on the effect particular gene-environment interactions might have in the development of atopy.The most important lesson learned through this tremendous research effort is that not only a small number but thousands and millions of separate risk factors act in concordance in the production of the allergic phenotype.

Childhood asthma and human leukocyte antigen type

Little is known about the relationship between human leukocyte antigen (HLA) class II genes and family history of asthma or atopy in relation to the incidence of childhood asthma. The objective of the study was to determine whether specific HLA class II genes (e.g., DRB1*03) are associated with asthma and whether such association explains the influences of family history of asthma or atopy on asthma incidence. A stratified random sample of 340 children who had HLA data available from the Rochester Family Measles Study cohort (n= 876) and a convenience sample of healthy children aged 5-12 years were the participants. We conducted comprehensive medical record reviews to determine asthma status of these children. The associations between the presence of specific HLA alleles and development of asthma and the role of family history of asthma or atopy in the association were evaluated by fitting Cox models. The cumulative incidence of asthma by 12 years of age among children who carry HLA DRB1*03 was 33%, compared to 24.2% among those who did not carry this allele. Adjusting for family history of asthma or atopy, gender, low birth weight, season of birth, HLA DRB1*04, and HLA DQB1*0302, the hazards ratio for HLA DRB1*03 carriers was 1.8 (95% confidence interval: 1.1-2.9, P= 0.020). We concluded that the HLA DRB1*03 allele is associated with asthma. However, the HLA class II gene does not explain the influences of family history of asthma or atopy on development of asthma. The mechanism underlying the association between asthma and HLA genes needs to be elucidated.

The DR4-DQ8 haplotype and a specific T cell receptor Vbeta T cell subset are associated with absence of allergy to Can f 1

BACKGROUND

The significance of specific T cell receptor (TCR) Vbeta subtypes and human leucocyte antigen (HLA) class II alleles for the development of allergy to lipocalin allergens such as the major dog allergen Can f 1 is not clear at present.

OBJECTIVE

To characterize the TCR Vbeta usage in the Can f 1-specific T cell lines and the HLA class II genotypes of Can f 1-allergic and non-allergic subjects.

METHODS

T cell lines were induced with recombinant Can f 1 from the peripheral blood mononuclear cells of 12 non-atopic dog owners and 26 dog-allergic patients. Thirteen of the dog-allergic subjects were sensitized to Can f 1. Expression of the TCR Vbeta subtypes on CD4(+) T cells in the T cell lines was measured by flow cytometry. The subjects were HLA genotyped for DRB1, DQB1 and DPB1 loci.

RESULTS

Can f 1-specific T cell lines were obtained from 18 subjects, with either positive (n=8) or negative (n=10) skin prick tests (SPTs) to recombinant Can f 1. The frequency of TCR Vbeta5.1(+) T cells was significantly higher in the T cell lines of subjects with negative SPTs to the allergen. Moreover, DR4-DQ8 haplotype was over-represented among these subjects.

CONCLUSION

The DR4-DQ8 haplotype and the TCR Vbeta5.1(+) CD4(+) T cells may be protective against allergy to Can f 1.

Transgenic mice expressing the T cell antigen receptor specific for an immunodominant epitope of a major allergen of house dust mite develop an asthmatic phenotype on exposure of the airways to allergen

BACKGROUND

Current studies on mechanisms underlying allergen-induced pulmonary inflammation and asthma are hampered by the lack of appropriate physiological in vivo models that reflect the natural route of allergen exposure and sensitization.

OBJECTIVE

To generate and phenotype a transgenic mouse strain expressing the T cell receptor (TCR) specific for an immunodominant domain of the major inhalant allergen Dermatophagoides pteronyssinus species of house dust mite (Der p 1), for the development of an in vivo model of allergic asthma.

METHODS

Der p 1 transgenic mice were generated using TCR-alphabeta derived from a CD4+ T cell hybridoma reactive with Der p 1 residues p 110-131. The frequency and functional activity of peripheral T cells were determined and parameters of airway inflammation assessed following allergen challenge of the airways with Der p 1.

RESULTS

CD4+ T cells are functionally active, exhibiting dose-dependent proliferation and IL-4 production on primary stimulation with Der p 1 or Der p 1, p 110-131 in vitro, independent of in vivo antigen priming. On sensitization of the airways with allergen, in the absence of systemic priming or the application of adjuvants, the TCR transgenic mice develop airway inflammation characterized by a marked lymphocytic and eosinophilic infiltrate with goblet cell hyperplasia and enhanced mucin production.

CONCLUSION

The Der p 1 TCR transgenic mice provide a model for investigating the pathophysiological mechanisms of pulmonary inflammation following sensitization by exposure of the airways to allergen and for investigating the mode of action and efficacy of novel immunotherapeutics.

The Spectrum of Allergens in Ragweed and Mugwort Pollen

Ragweed and mugwort are important allergenic weeds belonging to the Asteraceae or Compositae plant family. Pollen of mugwort is one of the main causes of allergic reactions in late summer and autumn in Europe and affects about 10-14% of the patients suffering from pollinosis. Ragweed pollen represents the major source of allergenic protein in the United States, with a prevalence of about 50% in atopic individuals. In Europe, ragweed allergy is now rapidly increasing particularly in certain areas in France, Italy, Austria, Hungary, Croatia, and Bulgaria. Amb a 1 and Art v 1, the major allergens of ragweed and mugwort, respectively, are unrelated proteins. Amb a 1 is an acidic 38-kDa nonglycosylated protein. The natural protein undergoes proteolysis during purification and is cleaved into a 26-kDa alpha chain, which associates noncovalently with the beta chain of 12 kDa. The two-chain form seems to be immunologically indistinguishable from the full-length molecule. Art v 1 is a basic glycoprotein comprising two domains: an N-terminal cysteine-rich, defensin-like domain and a C-terminal proline/hydroxyproline-rich module. The proline/hydroxyproline-rich domain was recently shown to contain two types of glycosylation: (1) a large hydroxyproline-linked arabinogalactan composed of a short beta1,6-galactan core substituted by a variable number (5-28) of alpha-arabinofuranose residues forming branched side chains with 5-, 2,5-, 3,5-, and 2,3,5-substituted arabinoses, and (2) single and adjacent beta-arabinofuranoses linked to hydroxyproline. As described for other pollen, ragweed and mugwort pollen also contain the pan-allergen profilin and calcium-binding proteins, which are responsible for extensive cross-reactivity among pollen-sensitized patients.

HLA antigens in Greek children with allergic bronchial asthma

The aim of our study was to investigate the genetic linkage between mite allergic bronchial asthma and HLA class I and II antigens and haplotypes. Sixty Greek children with allergic bronchial asthma due to mite sensitivity (Dermatophagoides pteronyssinus and Dermatophagoides farinae) and their family members were typed for HLA class I and II antigens (total 263 subjects). One hundred and twenty-five healthy, unrelated Greek children without medical history of atopy were also typed as control group. Major histocompatibility complex class I and II gene analysis revealed that only HLA-DRB1*04 and HLA-DQA1*0301 alleles are possibly important factors in the development of atopic asthma in Greek children with sensitivity to mites. No significant differences among the HLA-DRB1*04 subtypes have been established. Transmission disequilibrium test revealed that no specific HLA-A, -B, -DRB1, -DQA1 and -DQB1 alleles were transmitted preferentially to the affected children. HLA-DQB1*0301-4 alleles were associated with high levels of total serum immunoglobulin E in affected children. The study of the HLA haplotypes failed to demonstrate any significant association between any extended or natural selection haplotype and mite allergic bronchial asthma in Greek children.

Antigen presentation of the immunodominant T-cell epitope of the major mugwort pollen allergen, Art v 1, is associated with the expression of HLA-DRB1∗01

BACKGROUND

Mugwort pollen allergens are the main cause of pollinosis in late summer in Europe. Ninety-five percent of patients allergic to mugwort are sensitized to the major allergen Art v 1. In contrast to other common pollen allergens that contain multiple T-cell epitopes, Art v 1 contains only 1 immunodominant T-cell epitope (Art v 1 25-36 ).

OBJECTIVE

To characterize the minimal epitope of Art v 1 25-36 and to investigate a possible association of Art v 1 reactivity with HLA class II phenotypes.

METHODS

Art v 1-specific T-cell lines and clones were established from 51 patients with clinically defined mugwort pollen allergy and IgE specific for Art v 1. To define minimal epitopes and binding sites within Art v 1 25-36 , truncated and single-substitution analog peptides were used for T-cell stimulation. To study HLA restriction, monoclonal anti-HLA antibodies and antigen-presenting cells with defined HLA-DRB and -DQB1 alleles were used. HLA typing of patients with allergy was performed by hybridization with sequence-specific oligonucleotides, PCR, and nucleotide sequencing.

RESULTS

In 96% of the patients, a cellular response to Art v 1 25-36 was obtained, and a core region of 5 to 10 amino acids containing 3 to 5 amino acids essential for T-cell reactivity was defined. The frequency of HLA-DRB1 * 01 in patients recognizing Art v 1 25-36 was significantly increased as compared with healthy controls (69% vs 21%; odds ratio, 8.45; P < 10 -6 ), and HLA-DRB1 * 01 was identified as the main restriction element for the presentation of the immunodominant epitope.

CONCLUSIONS

Allergy to Art v 1 is characterized by a uniform T-cell response. The disease is apparently associated with the HLA-DR1 phenotype. Therefore, mugwort pollinosis is an ideal candidate for a peptide-based immunotherapy.

Gene-gene interaction between interleukin-4 and interleukin-4 receptor alpha in Korean children with asthma

BACKGROUND

Interleukin-4 receptor alpha (IL-4Ralpha), which binds IL-4 and IL-13, is involved in signal transduction of those cytokines that lead to IgE production, and is also a key functional component of the Th2 lymphocyte phenotype.

OBJECTIVE

To determine whether IL-4 and IL-4Ralpha polymorphisms are associated with susceptibility to asthma and whether there are gene-gene interactions between IL-4 and IL-4Ralpha polymorphisms.

METHODS

We genotyped three groups of Korean children, consisting of 196 atopic asthmatics, 60 non-atopic asthmatics, and 100 healthy children, for an IL-4 promoter polymorphism (C-590T) and three IL-4Ralpha polymorphisms (Ile50Val, Pro478Ser, and Arg551Gln) using PCR-RFLP (restriction fragment length polymorphism) assays.

RESULTS

The allele frequencies of the IL-4 (C/T) polymorphism and the Ile50Val and Pro478Ser polymorphisms of IL-4Ralpha did not differ statistically among the three groups of children. For the Arg551Gln polymorphism, the combined genotype frequency of the Arg/Gln heterozygote and the Arg/Arg homozygote was significantly higher in atopic asthmatics (27.6%) than in healthy children (16.0%) (odds ratio (OR) = 1.97, 95% CI (confidence interval) = 1.07-3.71). The eosinophil fraction (%) and bronchial responsiveness were higher in children with the Arg/Gln and Arg/Arg genotype than in those with the Gln/Gln genotype (P = 0.036 and 0.024, respectively). In asthmatic children, combinations of the IL-4 CT/TT genotype and the IL-4Ralpha Arg/Gln and Arg/Arg genotypes were associated with significantly increased risk for development of asthma (OR = 3.70, 95% CI = 1.07-12.78, P = 0.038).

CONCLUSIONS

In Korean children, the IL-4Ralpha Arg551 allele may play a role in susceptibility to atopic asthma and correlate with markers of asthma pathogenesis, including increased eosinophil fraction and enhanced bronchial hyper-responsiveness. In addition, a significant gene-gene interaction between the IL-4-590C and the IL-4Ralpha Arg551 allele significantly increases an individual's susceptibility to asthma.

Association studies for asthma and atopic diseases: a comprehensive review of the literature

Hundreds of genetic association studies on asthma-related phenotypes have been conducted in different populations. To date, variants in 64 genes have been reported to be associated with asthma or related traits in at least one study. Of these, 33 associations were replicated in a second study, 9 associations were not replicated either in a second study or a second sample in the same study, and 22 associations were reported in just a single published study. These results suggest the potential for a great amount of heterogeneity underlying asthma. However, many of these studies are methodologically limited and their interpretation hampered by small sample sizes.

HLA class II genotypic frequencies in atopic asthma: association of DRB1*01-DQB1*0501 genotype with Artemisia vulgaris allergic asthma

Different human leukocyte antigen (HLA) class II alleles have been associated with the development of atopic asthma. To determine whether HLA class II alleles are associated with atopic asthma in a population from southeast Spain (Murcia region), 213 atopic asthmatic patients and 150 controls were selected for HLA typing. Significant association of the DRB1*01 and DQB1*0501 alleles was found in Artemisia vulgaris allergic patients (p(c) = 0.00052 and p(c) = 0.00023, respectively). No significant correlation was found in other atopic patients allergic to pollens (Phleum pratense, Olea europaea, and Salsola kali), house dust mites (Dermatophagoides pteronyssinus, D. farinae), molds (Alternaria alternata, Cladosporium herbarum), or animal danders (dog, cat). The results reveal that the DRB1*01-DQB1*0501 genotype is strongly associated with a positive response to Artemisia vulgaris in the population studied.

The -159 C-->T polymorphism of CD14 is associated with nonatopic asthma and food allergy

BACKGROUND

CD14, the receptor for LPS, plays an important role in innate immunity. A polymorphism in the promotor for CD14, -159 C-->T, has been implicated in atopy.

OBJECTIVE

We explored the relationship of this polymorphism with both atopic and nonatopic asthma, as well as with food allergy.

METHODS

Patients with asthma and food allergy were recruited along with nonatopic, nonasthmatic control subjects. The -159 C-->T polymorphism was genotyped by using the PCR-based RFLP assay.

RESULTS

The -159 T allele was more common among patients with nonatopic asthma and food allergy than among control subjects (chi(2) = 6.03, P =.01 and chi(2) = 4.94; P =.03, respectively). Patients with food allergy had a 4-fold increased odds of having the TT genotype versus carriers of the C allele compared with control subjects (odds ratio [OR] = 3.9, 95% CI = 1.5-10.3), whereas patients with nonatopic asthma had a 3-fold increased odds of having the TT genotype (OR = 3.1 [95% CI = 1.1-9.1]). Controlling for sex differences between groups did not alter this relationship, which remained significant for patients with food allergy (OR = 3.7 [95% CI = 1.4-10.1]) or nonatopic asthma (OR = 2.7 [95% CI = 0.9-8.0]). We performed a stratified analysis, limited to white patients, to reduce population stratification. The relationship with the TT genotype was stronger in white patients with nonatopic asthma (OR = 4.4 [95% CI = 1.3-14.8]) and patients with food allergy (OR = 5.1 [95% CI = 1.6-16.2]), even adjusting for sex differences (OR = 3.9 [95% CI = 1.1-13.5] and OR = 4.6 [95% CI = 1.4-14.8], respectively).

CONCLUSIONS

The TT genotype of -159 C-->T CD14 is associated with nonatopic asthma and food allergy, particularly in white subjects. Thus CD14 is a candidate gene specifically for nonatopic asthma and not for asthma in general. This indicates that atopic and nonatopic asthma might be distinct conditions in their genetic predisposition, despite the fact that they are very similar once they have been established.

Genetic analyses in asthma: current concepts and future directions

Asthma is a complex genetic disorder with a heterogeneous phenotype, largely attributed to the interactions among many genes and between these genes and the environment. Numerous loci and candidate genes have been reported to show linkage and association of asthma and the asthma-associated phenotypes, atopy, elevated immunoglobulin E (IgE) levels, and bronchial hyper-responsiveness to alleles of microsatellite markers and single nucleotide polymorphisms (SNPs) within specific cytokine/chemokine, and IgE regulating genes. While many studies reporting these observations are compelling, only one asthma gene conferring high risk has been mapped. In this review, we present studies that support linkage and/or associations to the various genetic loci and genes in asthma. The first genome-wide scan for linkage to quantitative traits underlying asthma identified linkage on chromosome 4q, 6, 7, 11q, 13q and 16. A genome scan in American families from three racial groups revealed linkage to chromosome 2q, 5q, 6p, 12q, 13q and 14q. A two-stage scan in Hutterite families from the US found linkage on chromosome 5q, 12q, 19q and 21q. A screen in German families identified linkage to asthma on chromosome 2q, 6p, 9 and 12q and a two-stage genome scan in French families found replicated linkage on chromosomes 1p, 12q and 17q. A study of asthma in Finland showed linkage to high IgE on 7q14. Apart from a European linkage study of 199 families with atopic dermatitis, which demonstrated significant linkage to chromosome 3q21, three other studies have reported linkage results of genome-wide significance, including a linkage study in 175 Icelandic asthma families (14q24), a study in 533 Chinese families with bronchial hyper-responsiveness (chromosome 2) and a study in 47 Japanese families with mite-sensitive atopic asthma (5q31), suggesting that these regions may harbor genes contributing to the development of asthma and allergies. While significant progress has been made in the field of asthma genetics in the past decade, the clinical implications of the genes and genetic variations within the numerous candidate asthma genes that have been found to associate with the expression of the asthmatic phenotype, remain undetermined.

Genetics and genomics of asthma and allergic diseases

Asthma and eczema (atopic dermatitis) are characterized by a number of unexplained phenomena: the familial aggregation of disease, the initiation of disease by apparently trivial exposure to allergens, the preferential transmission of disease from affected mothers and the large increase in prevalence of disease in Westernized societies in the last century. A number of genes and chromosomal regions have been identified that consistently show linkage to asthma and its related phenotypes. Known loci modify the strength of the atopic response, nonspecific inflammation, the ability to respond to particular allergens and nonspecific airway reactivity. Eczema has been shown to be due to a different set of genetic loci that are shared with other skin diseases such as psoriasis and leprosy. Genetic and genomic studies both provide evidence that epithelial surfaces are active in the induction of allergic disease.

Evidence for the genetic control of immunoglobulin E reactivity to the allergens of Alternaria alternata

BACKGROUND

The fungus Alternaria alternata contains potent allergens, and sensitization to these allergens is associated with a high risk of respiratory disease. The influence of genetic regulation on sensitization to Alternaria is unknown.

OBJECTIVE

To determine the influence of genetic factors on IgE responses to specific allergens of Alternaria.

METHODS

The concordance of skin prick test (SPT), radioallergosorbent test (RAST) and IgE-binding profiles of sera were examined from a large cohort of monozygotic and dizygotic twins.

RESULTS

Casewise concordance for a positive SPT response was monozygous (MZ) 66%: dizygous (DZ) 40% (P = 0.002). Logistic regression confirmed that casewise concordance was significantly stronger between MZ than DZ pairs. Immunoblotting against an Alternaria extract revealed 19 allergenic bands. The differences in concordance between the different bands were not significant for either the MZ (P = 0.97) or DZ (P = 0.84) groups. The pooled MZ : DZ difference in concordance was just significant (P = 0.049), suggesting an overall genetic effect on the response to Alternaria. This was reinforced by the comparison of the MZ and DZ correlations for total number of bands recognized (MZ r = 0.65; DZ r = 0.37, P = 0.015). Overall, there was a moderate correlation between the individual SPT weal size and RAST score (r(2) = 0.41) and a substantial correlation between the number of immunoblotted bands and RAST scores (r(2) = 0.79).

CONCLUSION

There is a strong genetic influence on IgE response to the mixture of Alternaria allergens and a lesser effect on IgE response to individual allergens.

Possible association between cockroach allergy and HLA class II antigens

BACKGROUND

Susceptibility to the development of allergic diseases is known to be associated with genetic components, as well as environmental factors. Although the genetics of immunoglobulin E, atopy, and asthma are complex, genetic markers are needed to identify populations at risk and to plan intervention studies.

OBJECTIVE

Human leukocyte antigen (HLA) class II genes play a major role in the control of immune response. We investigated the association between HLA class II alleles of DRB1 and DQB1 and the expression of atopy in cockroach-sensitive patients.

METHODS

Levels of total and specific immunoglobulin E were determined. Skin prick tests were performed. HLA class II typing was performed by the Polymerase chain reaction with sequence-specific primers. Distribution of the HLA genotypes of 32 cockroach-positive atopic patients from the inner city were compared with those of 32 healthy, nonatopic controls of Turkish Caucasian origin.

RESULTS

HLA class II gene analysis showed an increase of the HLA-DRB1*0701 and HLA-DQB1*02 alleles in atopic patients compared with nonatopic controls (31.3% vs 3.1% and 50% vs 15.6%, Pc < 0.036 and Pc < 0.021, respectively). Conversely, HLA-DRB1*15 allele was encountered more frequently in the control subjects. An association between cockroach sensitivity and cutaneous reactivity to other aeroallergens was observed (P < 0.001).

CONCLUSIONS

It is suggested that the higher frequencies of HLA-DRB1*0701 and HLA-DQB1*02 alleles are probably related to atopy rather than an association between class II antigens and cockroach allergy in this group of polysensitized, atopic individuals. Further studies may lead to a better understanding of the genetically determined susceptibility, and evaluate the individual effects of each locus (or allele) on sensitivity to specific allergens in the Turkish population.

Asthma genetics

Asthma is the most common chronic childhood disease in developed nations and is a complex disease that has high social and economic costs. Asthma and its associated intermediate phenotypes are under a substantial degree of genetic control. Identifying the genes underlying asthma offers a means of better understanding its pathogenesis, with the promise of improving preventive strategies, diagnostic tools, and therapies. A number of chromosomal regions containing genes influencing asthma and atopy have been identified consistently by different groups, and a role for several candidate genes has been established.

Positive association between HLA-DRB1*07 and specific IgE responses to purified major allergens of D. pteronyssinus (Der p 1 and Der p 2)

BACKGROUND AND OBJECTIVE

Human leukocyte antigen (HLA) class II gene products are involved in the antigen presentation of exogenous antigens. The aim of this study was to evaluate whether specific immunoglobulin (Ig)E responses to purified major allergens of Dermatophagoides pteronyssinus (Der p 1 and Der p 2) were associated with genotypes of HLA-DRB1 alleles.

SUBJECTS AND METHODS

Peripheral venous blood samples were collected from two groups of unrelated Korean adolescents: 168 subjects with positive skin response (wheal > or = 3 mm) to crude D. pteronyssinus allergens and 94 age-matched controls with negative skin response and low serum-specific IgE to crude D. pteronyssinus allergens. The former group was found to contain 104 with high serum-specific IgE to crude D. pteronyssinus allergens, 100 with high serum-specific IgE to Der p 1, and 122 with high serum-specific IgE to Der p 2. Genotypes of the HLA-DRB1 alleles were determined using polymerase chain reaction-sequence specific oligonucleotide probes.

RESULTS

HLA-DRB1*07 was significantly higher in subjects with a high serum-specific IgE response to crude D. pteronyssinus allergens than the controls (16.3% vs 3.2%, odds ratio [OR] = 5.93, corrected P [Pc] = 0.02). The excess of DRB1*07 was more marked in those with high serum-specific IgE responses to Der p 1 or Der p 2 than the controls (20.0% vs 3.2%, OR = 7.58, Pc = 0.004; 18.9% vs 3.2%, OR = 7.05, Pc = 0.006). Among subjects with high serum IgE to Der p 1, DRB1*13 significantly increased than the controls (32.0% vs 13.8%, OR = 2.93, Pc = 0.03).

CONCLUSIONS

We clearly observed the association between HLA-DRB1 alleles and specific IgE responsiveness to D. pteronyssinus major allergens. The molecular mechanism of HLA-DRB1*07 and DRB1*13 involvement in D. pteronyssinus-specific IgE responsiveness awaits further investigation.

Current concepts on the genetics of asthma

Asthma is a complex genetic disorder with variable phenotype, largely attributed to the interactions of the environment and multiple genes, each potentially having small effects. Numerous asthma and atopy loci have been reported in studies demonstrating associations and/or linkage of the asthma-associated phenotypes, atopy, elevated IgE levels, and bronchial hyperresponsiveness to alleles of microsatellite markers and single nucleotide polymorphisms within specific cytokine/chemokine and IgE regulating genes. Although the studies reporting these observations are compelling, most of them lack statistical power. This review compiles the evidence that supports linkage and associations to the various genetic loci and candidate genes. Whereas significant progress has been made in the field of asthma genetics in the past decade, the roles of the genes and genetic variations within the numerous candidate asthma genes that have been found to associate with the expression of the asthmatic phenotype remain to be determined.

Using single nucleotide polymorphisms as a means to understanding the pathophysiology of asthma

Asthma is the most common chronic childhood disease in the developed nations, and is a complex disease that has high social and economic costs. Studies of the genetic etiology of asthma offer a way of improving our understanding of its pathogenesis, with the goal of improving preventive strategies, diagnostic tools, and therapies. Considerable effort and expense have been expended in attempts to detect specific polymorphisms in genetic loci contributing to asthma susceptibility. Concomitantly, the technology for detecting single nucleotide polymorphisms (SNPs) has undergone rapid development, extensive catalogues of SNPs across the genome have been constructed, and SNPs have been increasingly used as a method of investigating the genetic etiology of complex human diseases. This paper reviews both current and potential future contributions of SNPs to our understanding of asthma pathophysiology.

Association of the TNF-alpha-308 (G-->A) polymorphism with self-reported history of childhood asthma

Asthma is a complex disease involving genetic and environmental aetiology. The tumour necrosis factor-alpha (TNF-alpha) and angiotensin-converting enzyme (ACE) genes have been implicated in asthma pathogenesis. This study investigated the association of a G-308A variant of TNF-alpha and an insertion/deletion (I/D) variant of ACE with a self-reported history of childhood asthma, in two population groups. At Northwick Park Hospital, London, 1,811 pregnant women attending for antenatal care were recruited. Participants with a self-reported history of childhood asthma, determined by a researcher-administered questionnaire, and controls with no personal or family history of asthma, of UK/Irish (cases n=20; controls n=416) and South Asian (cases n=6; controls n=275) origin were used in this study. Participants were genotyped for the TNF-alpha-308 and ACE I/D variants by a PCR-RFLP and PCR approach. The TNF-alpha-308 allele 2 (-308A) was significantly associated with self-reported childhood asthma in the UK/Irish (Odds ratios (OR): 2.6; 95% confidence intervals (CI): 1.1-6.2; P=0.03) but not in the South Asian population. The ACE DD genotype was not associated with childhood asthma in either population group. Gametic phase disequilibrium between the TNF-alpha-308 and ACE I/D variants was significantly different from zero in UK/Irish cases (delta=0.09; P=0.034). The TNF-alpha308 allele 2 or a linked major histocompatibility complex (MHC) variant may be a genetic risk factor for childhood asthma in the UK/Irish sample.

Evidence for a role of HLA DRB1 alleles in the control of IgE levels, strengthened by interacting TCR A/D marker alleles

BACKGROUND

MHC class II alleles at human chromosome 6p21.1 and alleles in the TCR A/D locus at human chromosome 14q11.2 have been implicated in susceptibility to specific allergies and the modulation of total serum IgE. It has also been hypothesized that HLA and TCR allelic interactions may have a strong influence on predisposition to allergic disease.

OBJECTIVE

This study was performed to investigate the influence of HLA-DRB and DQB1 alleles and D14S50 alleles (adjacent to TCR A/D locus on 14q11.2), individually and in-combination, on total serum IgE levels, and on the development of specific allergies.

METHODS

We performed an association study between HLA-DRB, HLA-DQB1 polymorphisms, D14S50 alleles, total serum IgE expression and specific allergies to house dust mite, grass pollens and cat fur. A sample of 181 individuals was drawn from a larger set of 2415 adults, sampled at random from a district in Nottingham.

RESULTS

Strong association was observed between HLA-DRB1*0701 allele and high total serum IgE expression (P < 0.001). D14S50 alleles alone showed no evidence for independent association. However, there was a significant interaction between DRB1*0701 and D14S50 allele 170 such that, when both were present, there was a further increase in total serum IgE levels.

CONCLUSION

This study suggests that DRB1*0701 allele is involved in the modulation of total serum IgE, and that there is an interaction between DRB1*0701 and a marker adjacent to TCR A/D in the control of IgE expression.

Genomic approaches to understanding asthma

Asthma is the most common chronic childhood disease in developed nations, and it is a complex disease that has high social and economic costs. Asthma and its associated intermediate phenotypes are under a substantial degree of genetic control. The genetic aetiology of asthma offers a means of better understanding its pathogenesis and, thus, improving preventive strategies, diagnostic tools, and therapies. Considerable effort and expense have been expended in attempts to detect genetic loci contributing to asthma susceptibility, and extensive candidate gene studies and a number of whole-genome screens have been undertaken. This article reviews the current state of knowledge of the genetics of asthma, with a focus on genomic approaches to understanding allergic diseases.

Contributing factors to the pathobiology. The genetics of asthma

Markers in 19 chromosomal regions have shown some evidence of linkage to asthma, atopy, or related phenotypes in multiple independent genome-wide searches. Linkages to five of these regions (5q, 6p, 11q, 12q, and 13q) have also been reported in non-genome-wide screens. In addition, at least two independent studies have reported linkages to markers on 16p. Numerous candidate genes in these regions have shown varying levels of association to asthma or atopic phenotypes, potentially implicating them as disease susceptibility loci. These include the IL4, CD14, and B2ADR genes on 5q, the HLA-DRB1 and TNF genes on 6p, the FCERB1 and CC16 genes on 11q, and the IL4RA gene on 16p. It still remains to be determined whether polymorphisms in these genes account for the reported linkages in these regions. Studies are underway in laboratories around the world to identify the disease-causing variations in these genes that account for the linkages just discussed. Identifying specific genetic polymorphisms that influence asthma and atopic phenotypes will shed light on the molecular pathways involved in these complex disorders and provide a better understanding of the pathophysiology of asthma and atopy.

HLA-DRB1*01 alleles are associated with sensitization to cockroach allergens

BACKGROUND

Sensitization to cockroach allergens is an important epidemiologic risk factor for asthma, particularly among African Americans living in urban environments. A recent genome screen in the Hutterites, a white founder population, identified a linkage between an HLA-linked marker and sensitization to cockroach allergens.

OBJECTIVE

Our purpose was to determine whether alleles at one or more HLA loci are associated with sensitization to cockroach allergens in ethnically diverse populations.

METHODS

Alleles at 14 HLA region loci were studied in the Hutterites. On the basis of these results, selected loci were examined in 54 African Americans with cockroach sensitization (cases) and 65 African Americans without cockroach sensitization (controls). Sensitivity to cockroach allergens was assessed in both samples by skin prick test to purified cockroach allergens (Periplaneta americana and Blatella germanica).

RESULTS

Significant associations between cockroach allergies and DRB1*0101 (P(corrected) =.0066), DQA1*0101 (P(corrected) =.0012), and DQB1*0501 (P(corrected) =.00096) were detected in the Hutterites. In the African American sample, the most significant association was with the DRB1*0102 allele (P(corrected) =.0088, odds ratio 16.4, 95% confidence interval 2.0, 131). The DRB1*0101 allele was infrequent in the African American sample (frequency 0.06) and the DRB1*0102 allele was absent in the Hutterites. DRB1*0101 and DRB1*0102 are closely related alleles that differ from nearly all other DRB1 alleles at 3 amino acids in the 1 peptide binding domain of the HLA-DR molecule.

CONCLUSIONS

The DRB1*0101 allele in the Hutterites and the DRB1*0102 allele in African Americans confer risk for cockroach sensitization. Elucidating this interaction at the molecular level may allow for more targeted treatment and prevention of atopic asthma in inner-city populations.

Analysis of the phenotypic distribution of HLA class I and class II in atopic and non-atopic asthma patients

In several studies the HLA system has been implicated in the development of asthma, but the importance of the associations between HLA genes and asthma remains unclear. The aim of this study was to determine the HLA class I and II phenotypic frequencies in a population of asthmatics, and to analyse the relationship between these phenotypes and any type of asthma. We typed HLA class I and II antigens in a series of 189 asthmatic individuals (102 atopic and 87 non-atopic), and in a control population of 150 unrelated healthy Caucasoid donors. When the HLA phenotypic frequencies were compared, no statistical differences were found. Therefore, no definitive HLA association could be established with atopic or non-atopic asthma in the studied population. Abbreviations AA, atopic asthma; FEV1, forced expiratory volume in 1 s; NAA, non-atopic asthma; PCR, polymerase chain reaction; SSOP, sequence-specific oligonucleotide probes; SPT, skin prick test.

Pocket 4 in the HLA-DRB1 antigen-binding groove: an association with atopy

BACKGROUND

Many studies have attempted to identify an association between HLA genes and atopy, given the role of HLA molecules in the regulation of the immune response. In the case of house-dust mites, it is difficult to find an association with a particular HLA allele, due to the complexity of the allergen. The objective was to investigate whether HLA-DRB1 functional groups are better correlated with the atopic disease in our population than DRB1 alleles.

METHODS

The method was reanalysis of the HLA-DRB1 data of a previous case/ control study.

RESULTS

The "Dr" group was found to be associated with the atopic disease in our population.

CONCLUSIONS

Grouping HLA-DRB1 alleles into functional categories may assist in the search for predictive factors in relation to atopic disease.