HLA-DR4-associated nonresponsiveness to mountain-cedar allergen

Mountain cedar allergy: A review of current available literature

OBJECTIVE

To review the literature related to mountain cedar in terms of allergic disease and societal impact.

DATA SOURCES

English-language articles obtained through PubMed searches with relevance to mountain cedar allergies.

STUDY SELECTIONS

Articles with the following search terms were included: mountain cedar, Juniperus ashei, juniper, allergy, pollen, cedar fever, Jun a 1, and San Antonio.

RESULTS

A total of 61 relevant articles were selected regarding mountain cedar and its distribution, phylogenetics, allergens, potency, cross-reactivity, pollen counting and monitoring, symptoms, diagnosis, treatment, and future research.

CONCLUSION

Mountain cedar remains a major cause of allergic rhinoconjunctivitis in the south central United States during the winter months. Key treatment strategies involve a combination of allergen avoidance, pharmacologic therapy, and subcutaneous immunotherapy. Allergists can help affected patients in their management of "cedar fever."

T-cell epitopes of aeroallergens

OBJECTIVE

To describe the current knowledge of the T-cell epitopes of common aeroallergens, how they were discovered, and implications for future therapy.

DATA SOURCES

PubMed search of English-language articles without date limits pertaining to T-cell epitopes of aeroallergens included on a standard skin test panel.

STUDY SELECTION

A total of 127 articles were screened based on the results of the PubMed search and cross-indexed as needed. The highest quality and most clinically relevant articles were included for discussion.

RESULTS

Of the 47 allergen extracts included on the standard skin test panel at our instittition, T-cell epitopes have been described for 13. Immunodominant epitopes have been used for peptide immunotherapy trials.

CONCLUSIONS

T-cell epitopes have been characterized for a minority of common aeroallergens. However, knowledge is rapidly expanding and can lay the groundwork for therapies that specifically target T cells.

HLA-DRB4 as a genetic risk factor for Churg-Strauss syndrome

OBJECTIVE

To explore the association between HLA alleles and Churg-Strauss syndrome (CSS), and to investigate the potential influence of HLA alleles on the clinical spectrum of the disease.

METHODS

Low-resolution genotyping of HLA-A, HLA-B, and HLA-DR loci and genotyping of TNFA -238A/G and TNFA -308A/G single-nucleotide polymorphisms were performed in 48 consecutive CSS patients and 350 healthy controls.

RESULTS

The frequency of the HLA-DRB1*07 allele was higher in the CSS patients than in controls (27.1% versus 13.3%; chi(2) = 12.64, P = 0.0003, corrected P [P(corr)] = 0.0042, odds ratio [OR] 2.42, 95% confidence interval [95% CI] 1.47-3.99). The HLA-DRB4 gene, present in subjects carrying either HLA-DRB1*04, HLA-DRB1*07, or HLA-DRB1*09 alleles, was also far more frequent in patients than in controls (38.5% versus 20.1%; chi(2) = 16.46, P = 0.000058, P(corr) = 0.000232, OR 2.49, 95% CI 1.58-3.09). Conversely, the frequency of the HLA-DRB3 gene was lower in patients than in controls (35.4% versus 50.4%; chi(2) = 7.62, P = 0.0057, P(corr) = 0.0228, OR 0.54, 95% CI 0.35-0.84). CSS has 2 major clinical subsets, antineutrophil cytoplasmic antibody (ANCA)-positive, with features of small-vessel vasculitis, and ANCA-negative, in which organ damage is mainly mediated by tissue eosinophilic infiltration; analysis of HLA-DRB4 in patients categorized by different numbers of vasculitic manifestations (purpura, alveolar hemorrhage, mononeuritis multiplex, rapidly progressive glomerulonephritis, and constitutional symptoms) showed that its frequency strongly correlated with the number of vasculitis symptoms (P for trend = 0.001).

CONCLUSION

These findings indicate that HLA-DRB4 is a genetic risk factor for the development of CSS and increases the likelihood of development of vasculitic manifestations of the disease.

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.

Major mountain cedar allergen, Jun a 1, contains conformational as well as linear IgE epitopes

We have previously identified four linear IgE epitopes on Jun a 1, the dominant allergen in mountain cedar pollen, and mapped these to the surfaces of a molecular model and to the crystal structure of this glycoprotein. The aim of the present study was to determine if Jun a 1 also displays conformational IgE epitopes. Jun a 1 was denatured by heating at 75 degrees C for 1h, exposure to 6M guanidine or by reductive alkylation in the presence and absence of guanidine. The effects of these manipulations on the binding to IgE from patients with mountain cedar hypersensitivity was evaluated by an ImmunoCAP inhibition assay, using Jun a 1-specific caps. Treatment-associated changes in the 3D-structure were assessed by dynamic light scattering and CD spectroscopy. IgE binding to native Jun a 1 was inhibited 92+/-9% by soluble native protein and 92+/-9% by reduced and alkylated Jun a 1. However, the capacity of Jun a 1 to inhibit the binding of IgE antibodies was significantly diminished upon denaturation by heat, guanidine alone, or reduction and alkylation in guanidine, compared to native Jun a 1. Reductive alkylation treatment under denaturing conditions also increased the Stoke's radius, suggesting that the protein was partially unfolded. Analysis of the circular dichroism (CD) spectra suggested that heating and treatment with guanidine caused a loss of alpha-helical structure. Guanidine also caused an increase in random coil structure. Thus, at least a portion of the anti-Jun a 1 IgE antibodies produced by allergic humans recognize conformational epitopes and it is likely that some of these epitopes reside in alpha-helical structures of Jun a 1.

HLA class II DPB1, DQA1, DQB1, and DRB1 genotypic associations with occupational allergic cough to Bunashimeji mushroom

We previously reported that two-third of workers in a Bunashimeji mushroom (Hypsizigus marmoreus) farm complained of respiratory allergic symptoms, but one-third workers did not suffer from such symptoms even when working for a long period. CD4+ T-helper (Th) cells increased, and Th2/Th1 ratio increased in the allergic workers. To address these immunological backgrounds, we have investigated whether there is any relationship between mushroom allergy and human leukocyte antigen (HLA) class II alleles of DPB1, DQA1, DQB1, and DRB1 by using the polymerase chain reaction-restriction fragment length polymorphism (RFLP) and sequencing-based typing methods. We observed that the allele frequencies of DQA1*0103, DQB1*0601, and DRB1*0803 were significantly higher in the workers having no allergic symptoms than allergic workers (DQA1*0103: 57 vs 25%, DQB1*0601: 49 vs 14%, and DRB1*0803: 29 vs 0%). However, this phenomenon was not seen in workers producing another kind of mushroom, Honshimeji (Lyophyllum aggregatum). The HLA-DRB1*0803 allele alone, the DRB1*0803, DQA1*0103, DQB1*0601 haplotype, or both were negatively associated with allergy to Bunashimeji, and these alleles might be involved in the prevention of Bunashimeji mushroom-specific respiratory allergy.

Analysis of HLA in children with gelatin allergy

Systemic immediate reactions including anaphylaxis to gelatin in vaccines have been reported. However, the number of such reports is very small compared with the number of children exposed to gelatin. The present study was designed to investigate whether susceptibility or resistance to gelatin allergy is associated with human leukocyte antigen (HLA) class II gene. Blood samples were obtained from 49 patients with gelatin allergy and specific IgE to gelatin. DNA-based HLA class II typing was performed to determine the DRB1, DQB1 and DPB1 alleles. Genotype frequencies were compared with those found in 240 unrelated controls. The frequency of DQB1*0303 (55.1%) was significantly higher in the patients than in the control subjects (32.1%). The frequency of DPB1*0402 was also significantly higher in the patients (32.7%) than in the control subjects (15.4%). On the other hand, the frequency of subjects carrying DRB1*15 (DRB1*1501 and DRB1*1502) was significantly lower among the patients group (18.4%) than among the controls (40.8%). We found that DQB1*0303 and DPB1*0402 were positively associated with the IgE response for gelatin, while DRB1*15 was negatively associated with it.

Cockroach allergen Bla g 2: structure, function, and implications for allergic sensitization

Exposure to German cockroach (Blattella germanica) allergens is associated with the development of chronic respiratory diseases, especially asthma. The mechanism by which allergic patients develop specific immunoglobulin E (IgE) responses to environmental allergens is unknown. However, recent reports provided evidence that enzyme activity, especially proteolytic activity, was a major contributor to allergenicity. Bla g 2 is one of the most potent cockroach allergens (prevalence of IgE responses of 60 to 80%) and shows homology to the aspartic proteinase family of enzymes. We investigated whether the allergenicity of Bla g 2 was linked to its putative enzymatic function. A molecular model of Bla g 2, based on the high resolution crystal structures of pepsin and chymosin, showed that the overall three-dimensional structure of Bla g 2 was similar to that of aspartic proteinases with a well-defined binding pocket. However, critical amino acid substitutions in the catalytic triads and in the "flap" region of the molecule suggested that Bla g 2 was inactive and homologous to mammalian pregnancy-associated glycoproteins. This was confirmed experimentally by enzyme assay. The results show dissociation between enzymatic activity and allergenicity for Bla g 2 and suggest that other genetic and environmental factors are important determinants of sensitization.

Association of HLA-DRB1(*)07 and DRB1(*)04 to citrus red mite (Panonychus citri) and house dust mite sensitive asthma

BACKGROUND

Specific IgE responses to allergens provide useful models for evaluating the genetic factors that control human immune responses. A recent survey demonstrated that the citrus red mite (Panonychus citri, CRM) is the most important allergen in the development of asthma in citrus farmers.

OBJECTIVE

The aim of this study was to evaluate whether susceptibility or resistance to CRM-induced asthma was associated with HLA-DRB1 gene.

METHODS

DNAs were extracted from two groups of unrelated Korean adults living around citrus farms: (1) Ninety-one adults with CRM-sensitive asthma; and (2) 98 exposed, healthy nonatopic controls. Genotypes of HLA-DRB1 alleles were carried out using PCR-based methods.

RESULTS

Allelic frequency of HLA-DRB1(*)07 was higher in the CRM-sensitive asthmatics compared to the controls (17.6% vs 4.1%, Pc = 0.01). Conversely, the frequency of DRB1*04 was lower in the CRM-sensitive asthmatics compared to the controls (19.8% vs 40.8%, Pc = 0.01). No significant difference was found in the distributions of the other HLA-DRB1 gene-encoded antigens between the two groups.

CONCLUSION

HLA-DRB1 genes may be involved in the development of CRM-induced asthma. In addition, HLA-DR7 may increase, and DR4 decrease, the risk of developing the asthma in CRM-exposed adults.

Evidence for the involvement of two different MHC class II regions in susceptibility or protection in allergic bronchopulmonary aspergillosis

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is a disease with uncertain pathology. Studies have suggested a pathogenic role for T(H)2 cells. Previously, we demonstrated, in a small group of patients, that T(H)2 reactivity to a major Aspergillus fumigatus antigen was restricted by HLA-DR2 or HLA-DR5 alleles.

OBJECTIVES

We sought to confirm whether susceptibility to ABPA is exclusively associated with HLA-DR locus and to investigate the involvement of HLA-DQ genes in the development of ABPA.

METHODS

Genomic DNA was extracted from patients with ABPA, patients without ABPA but with positive A fumigatus skin test responses and asthma or cystic fibrosis, and healthy control subjects. HLA-DR and HLA-DQ genes were detected by using low-resolution typing; high-resolution typing was done only on HLA-DR2- and HLA-DR5-positive individuals by using sequence-specific primers (PCR-SSP).

RESULTS

A significantly higher frequency of HLA-DR2 was observed in patients with ABPA versus those without ABPA (corrected P <.01) or healthy control subjects (corrected P <.01). Genotype analysis revealed that susceptibility to ABPA is associated with HLA-DR2 alleles DRB1*1503 and DRB1*1501 and, to a lesser extent, with the HLA-DR5 allele DRB1*1104. The presence of DR4 or DR7 alleles in non-DR2/5 patients with ABPA suggests that these alleles may also be contributing factors in this disease. Another striking observation was the significantly high frequency of HLA-DQ2 in patients without ABPA (67. 4%) compared with patients with ABPA (20.5%) and normal control subjects (37.7%), suggesting that these alleles may confer protection in the population without ABPA.

CONCLUSION

These genetic studies suggest that HLA-DR molecules DR2, DR5, and possibly DR4 or DR7 contribute to susceptibility while HLA-DQ2 contributes to resistance and that a combination of these genetic elements determines the outcome of ABPA in patients with cystic fibrosis and asthma.

Cross-reactivity among conifer pollens

BACKGROUND

There are increasing reports of Cupressaceae pollinosis from various geographic areas. Cross-reactivity among a limited number of species within the Cupressaceae family has been suggested. Juniperus ashei (mountain cedar) is the leading cause of respiratory allergy in South Texas.

OBJECTIVE

This study examines in vivo and in vitro cross-reactivity among 12 Cupressaceae species, one Taxodiaceae species, one Pinaceae species, and an angiosperm.

METHODS

Cross-reactivity among pollen extracts of mountain cedar (MC) and the other 14 trees was investigated by: (1) prick skin testing of each tree pollen extract in ten patients with MC pollinosis. (2) Ouchterlony gel immunodiffusion employing rabbit antisera to MC. (3) IgE immunoblotting using high-titer MC pooled human sera, and immunoblot inhibition after pre-incubation with MC protein. (4) Monoclonal antibody immunoblotting using a murine monoclonal antibody with strong affinity for the gp40 major allergen of MC.

RESULTS

Positive skin wheal-and-flare responses occurred to all 12 Cupressaceae and Japanese cedar (the Taxodiaceae), but not to the Pinaceae or the angiosperm. In Ouchterlony gels, lines of identity or partial identity formed between MC and all pollens except the Pinaceae and the angiosperm. Immunoblots demonstrated IgE binding to the 40 to 42 kD protein in each Cupressaceae, and to a parallel band in Japanese cedar at 43 to 46 kD. Immunoblot inhibition by MC pollen was complete for all trees. The monoclonal bound both the 40 to 42 kD protein in 11 of 12 Cupressaceae species and the 46 kD band in Japanese cedar, but bound no protein bands in the Pinaceae or the angiosperm.

CONCLUSION

Pollen proteins of the 12 Cupressaceae (including MC) and the Taxodiaceae (Japanese cedar) are extensively cross-reactive. In particular, the MC major allergen, gp40, is cross-reactive with 40 to 42 kD proteins of the other Cupressaceae and with the Japanese cedar major allergen of 46 kD. Component-based immunotherapy may someday allow a standard treatment for both Juniper-allergic and C. japonica-allergic patients.

Molecular cloning of the mountain cedar (Juniperus ashei) pollen major allergen, Jun a 1

BACKGROUND

Cedar pollens cause allergic disease in diverse geographic areas. We have recently purified and characterized the major mountain cedar (Juniperus ashei) pollen allergen, Jun a 1.

OBJECTIVE

A full-length complementary DNA for Jun a 1 was cloned and sequenced, and the recombinant protein was expressed.

METHODS

Messenger RNA from mountain cedar pollen was purified and Jun a 1 sequences were established with use of reverse transcriptase-PCR and primers based on the N-terminal amino acid sequence of Jun a 1 and the homologous protein Cry j 1. Portions of the nucleotide sequence were confirmed by comparison with N-terminal amino acid sequencing of the intact tryptic fragments of the purified native protein. Recombinant Jun a 1 was cloned into pET 30, expressed in BL21, and purified by HPLC, and its allergenicity was analyzed by Western blotting with patient sera.

RESULTS

Jun a 1 possesses a high level of amino acid sequence homology with Cha o 1 and Cry j 1, the major allergens of Japanese cypress and Japanese cedar. The amino acid sequence of a region with putative pectate lyase activity was identical to that of Cry j 1 and Cha o 1. Jun a 1 contained 2 potential N-glycosylation sites that were distinct from those found in Cry j 1. The IgE from patient sera bound recombinant Jun a 1 in Western blot analysis.

CONCLUSION

The high degree of homology of Jun a 1 with Cha o 1 and Cry j 1 may explain the cross-reactivity of conifer pollens. Differences in N-glycosylation suggest little overlap of glycopeptide epitopes.

Isolation and characterization of the mountain cedar (Juniperus ashei) pollen major allergen, Jun a 1

BACKGROUND

Cedar pollens are important causes of seasonal allergic disease in diverse geographic areas.

OBJECTIVE

A major allergen from mountain cedar (Juniperus ashei) pollen, termed Jun a 1, was isolated and characterized.

METHODS

Water-soluble pollen glycoproteins were extracted, salt precipitated, and purified with use of concanavalin A affinity chromatography or HPLC. The purified fractions were characterized by SDS-PAGE, immunoblotting, and N-terminal amino acid sequence analysis. Binding of allergen-specific IgE from the sera of cedar-hypersensitive patients was detected by ELISA and antigen-specific responses of peripheral blood T cells by tritiated thymidine incorporation.

RESULTS

The major extractable cedar pollen glycoprotein had a molecular weight and N-terminal amino acid sequence that was similar to that of the major allergen Cha o 1, from Japanese cypress (Chamaecyparis obtusa), and Cry j 1, from Japanese cedar (Cryptomeria japonica). IgE from cedar-hypersensitive patients' sera bound to the isolated glycoprotein.

CONCLUSION

The predominance of Jun a 1 in the soluble proteins of mountain cedar pollen and its high degree of homology with Cha o 1 and Cry j 1 make it likely to be the major allergen of this pollen. Amino acid sequence conservation also makes Jun a 1 a potential target for cross-reactivity between these pollen allergens. The observed reactivity of IgE from the sera of Japanese cedar-sensitive patients with Jun a 1 is consistent with this proposition.

Limited genetic control of specific IgE responses to rye grass pollen allergens in Australian twins

BACKGROUND

Both genetic and environmental factors are thought to contribute to specific IgE responses, however, the relative contribution of each in the responses to individual ryegrass pollen allergens is largely unknown even though some responses to allergens have been linked to certain HLA complexes.

OBJECTIVE

Using a large group of monozygotic and dizygotic twins, this study was designed to investigate the IgE binding profiles of individual ryegrass pollen (Lolium perenne) components to assess the relative contribution of genetic and environmental factors in determining IgE responses to specific allergens.

METHODS

Ryegrass pollen proteins were separated by electrophoresis and immunoblotted with sera from 191 pairs of twins where at least one sibling had a SPT > 2 mm to perennial ryegrass. Concordance levels for individual ryegrass pollen components were compared between monozygotic and dizygotic twins in a subset group where both twins had SPT > 3 mm to perennial ryegrass.

RESULTS

Immunoblotting revealed 23 individual IgE-binding components from ryegrass pollen. Although there was a significantly greater proportion of monozygotic twins with SPT wheals greater than 3 mm when compared with the dizygotic twins, the mean case-wise concordance for the immunoblot components was similar for both groups of twins. The mean case-wise concordance when at least four pairs of sera were involved was 44% for the MZ twins (n=11 components) and 45% for the DZ twins (n=12 components). We found no significant differences in concordance levels for any of the 23 individual components including allergens previously associated with HLA.

CONCLUSION

Evidence for genetic control of allergen-specific IgE responses in a large population sample of twins to individual ryegrass allergens is limited, indicating that the IgE responses to specific ryegrass pollen allergens are determined largely by environmental factors.

Association of responsiveness to the major pollen allergen of Parietaria officinalis with HLA-DRB1* alleles: a multicenter study

Parietaria, a plant belonging to the family of Urticaceae, is a major source of allergenic pollen in Europe. In the context of a multinational study, we investigated whether in allergic subjects antibody response towards Par o 1, the major allergen from P. officinalis, was associated with defined HLA-DRB1* alleles. The study population consisted of 234 allergic patients: 65 from Bulgaria, 30 from Israel, 99 from Italy, and 40 from Spain. In the Italian study group, the prevalence of ST positivity to Parietaria was 77%. In Parietaria ST-positive subjects, the prevalences of IgG and IgE serum Ab towards Par o 1 were 91% and 75%, respectively. HLA-DRB1*1101 and/or 1104 were significantly positively associated with the presence of IgG Ab and with high levels of IgE Ab towards this allergen (p = 0.0007 and p = 0.012, respectively). In the Spanish study group, the positive association of DR1100 with responsiveness to Par o 1 was confirmed (p = 0.02, RR = 4, and p = 0.002, RR = 7, for IgG and IgE Ab, respectively). None of the Bulgarian patients had IgE Ab to Par o 1, whereas IgG Ab response was observed in 7 out of 65 subjects and was positively associated with DRB1*1101 and/or 1104 (p = 0.025). In the Israeli study group, responsiveness to Par o 1 was not associated with specific HLA-DRB1* alleles. In conclusion, this study shows that in allergic patients from three European populations antibody response to the major allergen from the pollen of Parietaria is associated with HLA-DRB1*1101 and/or 1104. Our data suggest that this association is stronger in subjects monosensitized to Parietaria.

Double-blind trial of house-dust mite immunotherapy in asthmatic children resident at high altitude

Twenty-three Dermatophagoides pteronyssinus (Dpt)-sensitive asthmatic children aged 7-14 years entered a double-blind, placebo-controlled trial of standardized immunotherapy (IT) (Alpare) while resident at high altitude. Dpt sensitivity was evaluated by skin prick tests at different allergen concentrations at the enrollment and after 6 and 12 months of treatment. Bronchial hyperreactivity was evaluated at the same time points, and on each occasion, histamine challenge and, the following day, Dpt bronchial challenge were performed. All patients, irrespective of active treatment, improved clinically and in lung function with increased PC20 and Dpt-PD20. Alpare-treated patients had a significantly decreased sensitivity on Dpt skin testing (P < 0.009) and felt that their asthma had improved (P < 0.001) compared with placebo-treated subjects, but there was no difference between the treatment groups in lung function or bronchial challenge response. IT neither increased nor decreased bronchial histamine sensitivity. Our results indicate that Dpt IT benefits asthmatic children, but improvement by allergen avoidance at high altitude is even greater.

HLA and atopic dermatitis with high serum IgE levels

Patients with atopic dermatitis usually exhibit allergen-specific IgE antibodies against several environmental antigens. HLA restriction is presumed to be involved in the recognition of such antigens, but several previous reports have so far failed to find a significant association between atopic dermatitis and HLA antigens. In this study we examined 38 unrelated Japanese patients with severe atopic dermatitis and high serum IgE levels (greater than 800 U/ml). We investigated the serological HLA types and HLA class II alleles in this group of patients with atopic dermatitis. Frequencies of HLA-A24, A33, Cwblank, B44, DR13 and HLA-DRB1*1302, DQB1*0604, DPB1*0301 alleles were increased in the patients. In contrast, frequencies of HLA-Cw1, Bw6, DR4, DR53, and HLA-DQB1*0302 allele were decreased. However, none of these remained significant after p values were corrected. Further study on HLA association with atopic dermatitis through characterization of specific antigens or antigen epitopes is needed.

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

In order to test for human histocompatibility leucocyte antigens (HLA) class II restriction of IgE responses, 431 subjects from 83 families were genotyped at the HLA-DR and HLA-DP loci and serotyped for IgE responses to six major allergens from common aero-allergen sources. A possible excess of HLA-DR1 was found in subjects who were responsive to Fel d I compared with those who were not (Odds Ratio (OR) = 2, P = 0.002), and a possible excess of HLA-DR4 was found in subjects responsive to Alt a I (OR = 1.9, P = 0.006). Increased sharing of HLA-DR/DP haplotypes was seen in sibling pairs responding to both allergens. Der p I, Der p II, Phl p V and Can f I were not associated with any definite excess of HLA-DR alleles. No significant correlations were seen with HLA-DP genotype and reactivity to any of the allergens. The results suggest class II HLA restriction is insufficient to account for individual differences in reactivity to common allergens.

DR7 and DQ2 are positively associated with immunoglobulin-E response to the main antigen of olive pollen (Ole e I) in allergic patients

We have studied the relationship between HLA class II haplotypes and alleles, and the IgE antibody response to a highly purified allergen, Ole e I, in allergic patients. Ole e I, is the major antigen from the pollen of olive tree that grows mainly in the Mediterranean. Genomic DNA typing was performed in 40 unrelated patients with seasonal allergic pollenosis who had specific IgE antibodies against Ole e I, detected by double-antibody radioimmunoassay. HLA-DRB and -DQB loci were analyzed by PCR-SSO and RFLP. Phenotypic frequencies were compared with those of 179 healthy unrelated individuals. Significant increases in the phenotypic frequencies of DR7 (pf = 67.5% vs 31.3% in the control population, pc = 0.0023) and DQ2 (pf = 90.0% vs 48.0%, pc = 0.0003) were found, indicating an association between DRB1*0701/2, DQB1*0201 alleles and the IgE antibody response to Ole e I. This is the first time that the HLA-DQ gene has been associated with a positive allergic response.

Genetic analysis of the linkage between chromosome 11q and atopy

Previous work has suggested that there is a genetic predisposition for the development of both asthma and atopy. A recent study has also shown that there is a striking link between chromosome 11q and the IgE response underlying asthma and rhinitis. To further assess the linkage between chromosome 11q and atopy, we have studied nine families of two and, in many instances, three generations with the index case having asthma and/or atopy. Using two restriction fragment length polymorphism probes associated with the regions 11q12-q13.2, namely PYGM and INT2, we have been unable to confirm a significant link between this region of chromosome 11q and atopy as defined by a positive skin-prick test and/or a raised specific IgE and/or a raised total IgE.