HLA immunogenetics and specific IgE responses to 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.

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.

Delayed hypersensitivity to aminopenicillins is related to major histocompatibility complex genes

BACKGROUND

Although in some cases delayed hypersensitivity may be observed, beta-lactam antibiotics frequently induce immediate allergic IgE-mediated reactions with the specificity localized in the acyl-side chain structure. Generally, delayed immunologic reactions are related to sensitized T lymphocytes and major histocompatibility complex restricted.

OBJECTIVE

To investigate the prevalence of HLA class I and II antigens in patients with delayed hypersensitivity to aminopenicillins in order to evaluate a relationship between major histocompatibility complex immune response genes and aminopenicillins hypersensitivity.

METHODS

We assessed 24 patients with history of delayed hypersensitivity to aminopenicillins using (1) skin test with penicilloyl polylysine, minor determinant mixture, benzylpenicillin, amoxicillin, and ampicillin; (2) patch tests with benzylpenicillin, amoxicillin, and ampicillin; (3) RAST for penicilloyls G and V; and (4) oral challenges with amoxicillin, ampicillin, and penicillin V in 18/24 patients. All patients were typed by microlymphotoxicity standard test for HLA class I and II antigens. Statistical analysis by chi2 test 2 x 2 contingency tables, according to Svejgaard, were used for comparison between patients and random Italian population (522 subjects).

RESULTS

In the patients group we found higher prevalence of HLA A2 (12/24 = 50%, RR = 6.76 P < .001, EF = 0.425), DRw52 (20/24 = 83.3%, RR = 9.28, P < .001, EF = 0.74), and lower frequency of DR4 (3/24 = 12% ns).

CONCLUSIONS

These data suggest that the immune mechanisms involved in adverse reactions to aminopenicillins in vivo are related to genetic markers of immune response and confirms that the presentation of penicillin-hapten determinants to lymphocyte is major histocompatibility complex restricted.

Non-specific airway hyperresponsiveness in mono-sensitive Sicilian patients with allergic rhinitis. Its relationship to total serum IgE levels and blood eosinophils during and out of the pollen season

BACKGROUND

Initial attempts to evaluate the association between allergic rhinitis and non-specific bronchial responsiveness has produced conflicting results. In fact, some studies showed a strong correlation and other failed to find an association. However, little is known about the effect of natural specific allergen exposure on the bronchial reactivity of mono-sensitive patients with rhinitis in the southern Mediterranean area, in relation to skin reactivity to allergens, total serum IgE levels and blood eosinophils.

OBJECTIVES

The significance of the association between allergic rhinitis, and abnormal airway responsiveness with regard to the pathogenesis of asthma is unclear. For this reason, we have studied non-specific bronchial hyperreactivity, in patients with seasonal allergic rhinitis, with reference to the responsible allergen. The aim of the study was to correlate the responsiveness to bronchoprovocation with methacholine in subjects a with allergic rhinitis during and out of the pollen season with total serum IgE and blood eosinophils.

METHODS

Fourty-nine non-smoking patients with clinical diagnosis of allergic rhinitis and mono-sensitive skin-prick tests to pollen allergens were enrolled in the study. Twenty patients suffered from seasonal rhinitis to Parietaria pollen, 15 patients to Gramineae pollen and 14 patients to Olea pollen. In all patients lung function measurements (assessed as response to methacholine), total serum IgE and blood eosinophil counts were measured during and out of the pollen season.

RESULTS

During pollen season, 16 out of 49 rhinitis patients demonstrated values of bronchial responsiveness measured as response to inhaled methacholine in the asthmatic range whereas out of the pollen season only eight patients were in the asthmatic range. By analysing the results with reference to the responsible allergen, during the pollen season 15 out of 16 patients were Parietaria-sensitive and out of the pollen season seven out of eight patients. Finally, in Parietaria-sensitive rhinitis bronchial responsiveness significantly correlated, during and out of the pollen season, with total serum IgE and with blood eosinophil counts.

CONCLUSIONS

Our results are consistent with the hypothesis that Parietaria is more important than Olea and Gramineae as a risk for developing non-specific bronchial hyperresponsiveness. On the whole, present observations provide further evidence that there is an interrelationship of allergen kind, total serum IgE, eosinophil and bronchial hyperresponsiveness suggesting that they may play a role in the development of bronchial asthma in rhinitis patients.