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Notes: Abstract  Immunoglobulin E responses to known environmental antigens (allergens) may serve as a general model to investigate germline genetic restriction of the immune response. We have previously shown genetic linkage between IgE responses to major allergens and the T-cell receptor (TCR) A/D locus, but not to TCR-B, implying that elements in TCR A/D restrict the ability to react to specific antigens. We now show, in two sets of subjects from the same population, a strong allelic association between a VA8.1 polymorphism (VA8.1 * 2) and reactivity to Der p II, a major antigenic component of the house dust mite Dermatophagoides pteronyssinus. Association was also seen between Der p II IgE titres and HLA-DRB1 * 1501 alleles. Reactivity to Der p II was confined to subjects who were positive for VA8.1 * 2 and HLA-DRB1 * 1501, demonstrating germline HLA-DR and TCR-A interaction in restricting the response to exogenous antigen.

Notes: The results of testing for linkage between atopy and the chromosome 11 marker D11S97 is shown for all the 723 subjects genotyped by us up to January 1992. Lod score estimations were confounded by the high population prevalence of atopy, maternal inheritance of atopy at the 11q locus, genetic heterogeneity, and excess of atopy in families not ascertained through a single proband. Affected sib-pair analysis shows evidence for linkage which is not dependent on the definition of atopy or model specification. We suggest that presentation of sib-pair data will be suitable for meta-analysis of the different studies of genetic linkage and atopy.

Notes: Background Stings from bees and wasps can cause systemic reactions which can be fatal in some individuals. In these venom-sensitive patients, specific IgE to the venom is produced and is considered to participate in the adverse reactions. This immune response requires antigen presentation by human leucocyte antigens (HLA) class II molecules, which includes DR and DP, which are present on antigen presenting cells.Objective To test for associations between HLA class II DRB1 and DPB1 alleles and life- threatening sensitivity to both bee and wasp venoms. To establish further whether any associations are independent of the atopy phenotype.Methods A total of 33 bee- and 44 wasp-venom-sensitive patients was studied. DRB1 genotypes were determined by single stranded oligonucleotide (SSO) probing of PCR products, and DPB1 genotypes by amplified fragment length polymorphism (AFLP) analysis. Total and specific IgE were measured using the Pharmacia Immunocap, FEIA. Patients with specific IgE to the venom antigens only were termed monosensitive and those with additional specific IgE to HDM and/or GP were termed polysensitive.Results Allele frequencies were compared to an unrelated control population. The 33 bee- sensitive patients had a greater prevalence of DRB 1*07 alleles than the control subjects, 26% vs 14%, with an odds ratio (OR) of 2.1 (95%CI, 1.2–3.7, P= 0.015, corrected for multiple comparisons, pc 〉 = ns). This association was confined to the 15 monosensitive bee patients, who had a 43% DRB 1*07 allele frequency when compared with 11% in the 18 polysensitive bee patients, OR 6.1 (95%CI, 1.73–22, P= 0.004, pc= 0.05), and when compared with a control group of non-venom subjects, 43% vs 16%, OR 3.9 (95% CI, 1.72–9.0, P= 0.002, pc= 0.02). The 44 wasp-sensitive patients had an increase in the DRB1*11 allele when compared with the control subjects, 13% vs 6%, with an OR 2.2 (95%CI, 1.0–4.6, P= 0.04, pc= NS), and a decreased prevalence of DRB 1*04 alleles, 10% vs 19%, with an OR 0.33 (95%CI, 0.24–0.99, P= 0.04, pc= NS), but these were not significant when multiple comparisons were taken into account. The DPB1 alleles were not significantly different between the venom sensitive patients and the controls.Conclusion Patients monosensitive to bee venom had a significantly greater prevalence of DRB 1 *07 alleles than the non-venom, control population suggesting that IgE responses in these patients may, in part be controlled by immune response HLA class II genes. These results are also suggestive of wasp-sensitive patients having a higher prevalence of DRB1*11 and a lower prevalence of DRB 1*04 than the control population.

Notes: Background Polymorphisms within the β subunit of the high-affinity receptor for IgE (FcεR1-β) on chromosome 11q13 have been related to atopy and asthma and the lymphotoxin α (LTα) gene on chromosome 6 is implicated in asthma.Objective To elucidate the association of polymorphisms in the FcεR1-β and LTα genes to IgE responses and asthma in a family-orientated rural population.Methods A total of 461 adult farmers, who participated in an epidemiological follow-up study on respiratory symptoms among farmers on the Swedish island of Gotland, were examined. The traits assessed included serum total IgE, IgE antibody responses to 21 common inhalant allergens and asthma.Results The 237G mutation was only detected in seven persons. Atopy was found to be associated with the RsaI-ex7 AB-genotype (OR = 1.9; P = 0.04). The RsaI-ex7 B allele had a significant influence on IgE responses to pollens and dust mites (OR = 5.5; P = 0.03 and OR = 5.2; P = 0.049, respectively). The influence of this allele was stronger when the association towards single dust mite species (Lepidoglyphus destructor) was estimated (OR = 7.1, P = 0.03) and the association increased even more when the major allergen of L. destructor (rLep d 2) was analysed (OR = 11.2, P = 0.02). These associations were independent of sex, age and smoking, and the estimates of RsaI-in2 independent of RsaI-ex7. RsaI-in2, RsaI-ex7 and LTα genotypes were unassociated with total serum IgE. No significant difference in the distribution of RsaI-in2, RsaI-ex7 and LTα genotypes was found among subjects with atopy or asthma compared to healthy controls.Conclusion This study supports the notion that polymorphisms in the FcεR1-β gene have significant effects on IgE responsiveness. Secondly, dust mites in rural populations influence the expression of genes on chromosome 11q13.

Notes: Background:  Dissecting complex diseases in underlying distinct traits and studying these for their genetic basis might enhance the power as well as the specificity, of detection of disease genes. These phenoypes are known as intermediate phenotypes.Objective:  We were interested in the atopic basis of asthma, and used the sensitization to mite (Dermatophagoides pteronyssinus) allergens as a pathophysiologically important intermediate phenotype.Methods:  This time we performed a genome-wide scan based on the same already used multiethnic European population consisting of 82 nuclear families with at least two affected siblings. We carried out nonparametric as well as parametric MOD-score analyses based on the genotypes of 603 microsatellite markers.Results:  In comparison with our first genome-wide candidate region search three novel regions additionally appeared to be significant. We obtained significant results for the region 2p12 with a MOD score of 3.35 and for the region 16q21 with a MOD score of 4.18. The most significant result was found for the region 3q21.3 with the same microsatellite marker, which showed significant linkage to atopic dermatitis (AD) in another study with a MOD score of 4.51 and an nonparametric linkage analysis (NPL) of 4.00.Conclusion:  Our findings indicate that atopy, allergic asthma, allergic rhinitis and AD on the one hand are distinct traits on both the clinical and genetic basis, but on the other hand, our results also underline that these traits are closely related diseases concerning the atopic basis of the traits.