Soy Gly m 8 sIgE Has Limited Value in the Diagnosis of Soy Allergy in Peanut Ara h 2-Sensitized Adults

INTRODUCTION

Recently, specific IgE (sIgE) sensitization against Gly m 8 (soy 2S albumin) has been described as a good diagnostic marker for soy allergy (SA). The aim of this study was to evaluate the diagnostic value of Gly m 8 by determining the sensitization profiles based on the homologues soy allergens Bet v 1, Ara h 1, Ara h 2, and Ara h 3.

METHODS

Thirty soy-allergic adults were included; sIgE to total soy extract, Gly m 8, Gly m 4, Gly m 5, Gly m 6, Bet v 1, Ara h 1, Ara h 2, and Ara h 3 were determined. Sensitization patterns were analyzed and determined. The clinical relevance of sIgE of Gly m 8 sensitization was measured by assessing its capacity to degranulate basophils in Gly m8-sensitized patients by an indirect basophil activation test (iBAT).

RESULTS

Based on the sIgE patterns of sensitization, two groups of SA patients were identified: (i) peanut-associated SA group (all patients were sensitized to one or more of the peanut compounds) and (ii) non-peanut/PR-10-associated SA group (22 patients were sensitized to Gly m 4 and Bet v 1 but not to any of the peanut compounds). A high and significant correlation between total soy extract and Gly m 6 (R2 = 0.97), Gly m 5 (R2 = 0.85), and Gly m 8 (R2 = 0.78) was observed. A nonsignificant correlation was observed between the levels of sIgE of Gly m 8 versus Ara h2. The iBAT results showed that Gly m 8 did not induce basophil degranulation in any of the peanut-associated patients, indicating that the Gly m8 sensitizations were not clinically relevant.

CONCLUSIONS

Gly m 8 was not a major allergen in the selected soy-allergic population. The iBAT results indicated that Gly m 8 was not able to induce basophil degranulation in sIgE Gly m 8-sensitized soy-allergic patients. Thus, Gly m 8 would have no added value in the diagnosis of SA in the present study population.

Targeting CD22 on memory B cells to induce tolerance to peanut allergens

BACKGROUND

Circulating IgE and subsequent severe allergic reactions to peanut are sustained and propagated by recall of peanut allergen-specific memory B cells.

OBJECTIVES

This study aimed to determine whether targeting mouse and human CD22 on peanut-specific memory B cells induces tolerance to peanut allergens.

METHODS

Siglec-engaging tolerance-inducing antigenic liposomes (STALs) codisplaying peanut allergens (Ara h 1, Ara h 2, or Ara h 3) and high-affinity CD22 ligand (CD22L-STALs) were employed in various mouse models (BALB/cJ, C57BL/6, human CD22 transgenic, and NSG) of peanut allergy. To investigate memory B cells, a conferred memory model was used in which splenocytes from peanut-sensitized mice were transferred into naive animals. Reconstituted mice received either CD22L-STALs or an immunogenic liposome control, followed by a peanut allergen boost and later a challenge with individual peanut allergens. To assess the effects of CD22L-STALs on human B cells, PBMCs were injected into NSG mice, followed by administration of human CD22L-STALs (hCD22L-STALs) and later a whole peanut extract boost. Blood was collected to quantify WPE- and Ara h 1-, 2-, and 3-specific immunoglobulins.

RESULTS

Mouse CD22L-STALs (mCD22L-STALs) significantly suppressed systemic memory to Ara h 1, Ara h 2, and Ara h 3 in BALB/cJ and C57BL/6 mice, as demonstrated by reduced allergen-specific IgE, IgG₁, and anaphylaxis on challenge. Importantly, 2 doses of mCD22L-STALs led to prolonged tolerance for at least 3 months. hCD22L-STALs displayed similar suppression in mice expressing human CD22 on B cells. Finally, human B cells were tolerized in vivo in NSG mice by hCD22L-STALs.

CONCLUSIONS

Antigen-specific exploitation of CD22 on memory B cells can induce systemic immune tolerance.

Nut sensitization profile in Southern Taiwan

BACKGROUND/PURPOSE

To evaluate the relationship between serum-specific immunoglobulin E (IgE) to peanuts/tree nuts and their clinical manifestations in atopic diseases.

METHOD

Serum from people with the classical symptoms of asthma, allergic rhinitis (AR), or atopic dermatitis (AD) was collected for the measurement of serum-specific IgE to peanuts, cashew nuts, Brazil nuts, almonds, and coconuts. Cases with possible sensitization to these nuts (serum specific IgE ≧ 0.35 kU/L) were selected and their clinical relationships with physician-diagnosed asthma, allergic rhinitis, or atopic dermatitis were analyzed.

RESULT

Compared with non-sensitization group, people with peanut/tree nut sensitization have higher prevalence of atopic dermatitis, but no such difference noted in the prevalence of allergic rhinitis. In the situation of asthma, people with sensitization to peanuts and Brazil nuts, but not other nuts, have higher prevalence of asthma than people without sensitization to any nut (p < 0.001 and p < 0.05, respectively). Binary logistic regression analysis also showed positive associations between peanut (OR: 1.164, p value = 0.017) and Brazil nut (OR: 1.304, p value = 0.055) sensitization and asthma. The associations between peanut and Brazil nut sensitization and asthma were independent of the prevalence of other atopic diseases.

CONCLUSION

People in Asia may have less severe allergic effects as in Western countries, but sensitization to specific food allergens such as peanuts or Brazil nuts may predispose individuals to asthma, which could be helpful in diagnosis and deserves more attention than previously considered.

The utility of peanut components in the diagnosis of IgE-mediated peanut allergy among distinct populations

BACKGROUND

Increasing data suggest that analysis of IgE to peanut components can be clinically helpful and possibly more accurate than IgE to whole peanut. Not all studies examining this topic, however, have used prospective samples, multiple components, and peanut challenges.

OBJECTIVE

We sought to determine the utility of peanut component testing, using a standardized, commercially available test done before oral peanut challenge in various populations of patients with suspected peanut allergy from 2 different countries.

METHODS

IgE to whole peanut and the recombinant allergen components Ara h 1, 2, 3, and 8 were analyzed from serum samples drawn before double-blind peanut challenge from 4 distinct cohorts of patients with suspected peanut allergy from 2 nations (United States and Sweden).

RESULTS

Patients (n = 167; median age, 11.7 years; interquartile range, 7.0-15.0 years) had serum analyzed for peanut components and completed an oral food challenge to peanut. Although IgE to peanut was the most sensitive test (0.93), Ara h 2 was the most specific (0.92) and provided the best positive predictive value (0.94) of all the tests. Ara h 2 was also the best overall diagnostic test by receiver operating characteristic analysis (area under the curve, 0.84; P < .05).

CONCLUSIONS

In patients with suspected peanut allergy, IgE to peanut is a sensitive test but is not specific. IgE to Ara h 2 is a more specific and more accurate diagnostic test in this sampling of patients with suspected peanut allergy. Given each tests attributes, a stepwise approach to testing may provide clinicians with a way to minimize the need for peanut challenges.