Standardized allergen extracts for allergen immunotherapy.

Nineteen U.S. allergen extracts were standardized by the U.S. Food and Drug Administration (FDA) between 1987 and 1998, including of two house-dust mites, short ragweed, cat hair and cat pelt, seven temperate and one southern grass, and six Hymenoptera venom preparations. Relevant literature was reviewed. For each allergen, a "representative" extract was established; the potency of each representative extract was determined by measurement of the total protein content (Hymenoptera venom), radial diffusion measurement of the dominant allergen (short ragweed and cat), or, if there was no dominant allergen, then by quantitative skin testing by using the ID50EAL (intradermal dilution for 50 mm sum of erythema determines the bioequivalent allergy units) method. In vitro tests were developed to allow the manufacturer to demonstrate that each lot of its extract was statistically identical, within defined limits, to the FDA reference extract. These tests included radial immunodiffusion, competitive enzyme-linked immunosorbent assay, and isoelectric focusing. The standardized extracts offer the advantage of consistent potency from lot to lot for each manufacturer and also from manufacturer to manufacturer, and assure the presence of recognized significant allergens within the extract. Therefore, standardized extracts offer improved safety and efficacy over their nonstandardized predecessors.

The Diagnostic Importance of Recombinant Allergen IgE Testing in Patients with Hymenoptera Venom Allergy: Comparison of Two Methods.

Adults with systemic anaphylactic reactions (SAR) to insect sting show often multiple-positivity of serum-specific IgE (sIgE) to Hymenoptera venoms. Unnecessary long-lasting venom-specific immunotherapies (VIT) in false-positive patients increase the risk of recurrent SAR. This report aims to analyze the diagnostic importance of recombinant allergen IgE testing in patients with SAR to Hymenoptera sting. In 82 patients we measured sIgE to honeybee venom (HBV), wasp venom (WV) and hornet venom (HV) extracts, recombinant phospholipase A2 from HBV (sIgE-rApi m1), recombinant antigen 5 from WV (sIgE-rVes v5), and cross-reactive carbohydrate determinants-CCD-bromelain by ImmunoCAP. We analyzed the correlation of ImmunoCAP and Immunoblot for HBV and WV extracts, rApi m1, and rVes v5 in 39/82 patients. According to the history of the culprit insect, we compared sensitivity and specificity between the two methods. The severity of the SAR does not depend on the sIgE level to venom extracts and recombinant allergens. Fifty-one percent of the patients had a multiple-positivity to HBV/WV or HBV/WV/HV extracts. Severe SAR and CCD-sIgE were more frequent in multiple-positive than single-positive patients. CCD-sIgE were more frequent in HBV allergic patients than WV and HV allergic patients. There was a significant correlation between levels of sIgE to venom extracts and recombinant allergens measured by ImmunoCAP and Immunoblot. ImmunoCAP has higher sensitivity and specificity than Immunoblot for diagnosis of SAR to Hymenoptera venoms. IgE testing to recombinant CCD-free allergens is necessary for the adequate selection of long-lasting VIT, especially in patients with multiple sensitivities to venom extracts.

Cross-reacting carbohydrate determinants and hymenoptera venom allergy.

PURPOSE OF REVIEW: Insect venom allergy is an important cause of anaphylaxis. Venom immunotherapy assume the clear identification of the culprit insect, but this is impeded by Immunoglobulin E (IgE) antibodies to cross reactive carbohydrate determinant (CCD) epitopes of common glycoproteins. Here we give an overview about inducers, importance, and relevance of anti-N-Glycan CCD IgE antibodies. RECENT FINDINGS: Pollen exposure and insect stings induce anti-CCD IgE antibodies interfering with in-vitro tests for allergy diagnosis due to extensive IgE cross-reactivity. Instead of being biologically active these antibodies are irrelevant for allergic reactions due to hymenoptera stings. The general response of the immune system to the ubiquitous exposure to N-glycan containing glycoproteins is still a matter of debate. CCD specific IgG antibodies in sera of bee keepers suggest tolerance induction due to high-dose exposure. Tolerance induction by pollen and food glycoproteins has not been proved. SUMMARY: Hymenoptera stings and pollen exposure induce anti-CCD IgE. In regard to anaphylaxis due to Hymenoptera stings these antibodies are not clinically relevant, but they are important for the specificity of in-vitro tests proving insect venom allergy. The introduction of component based diagnostic IgE testing improves the specificity of in-vitro tests if proteins devoid of CCD epitopes are used.

Immunoglobulin-E reactivity to wine glycoproteins in heavy drinkers.

N-glycans from plant and invertebrate allergens can induce extensive immunoglobulin-E (IgE) cross-reactivity in vitro. IgE antibodies against these N-glycans, also termed cross-reactive carbohydrate determinants or CCDs, are prevalent in alcohol drinkers. This study investigated the prevalence and biological significance of IgE antibodies to N-glycans from wine glycoproteins in heavy drinkers. A structured questionnaire, skin prick tests, serum IgE levels, IgE-immunoblotting to wine extracts, and basophil activation tests were used to characterize 20 heavy drinkers and 10 control subjects. Eleven heavy drinkers (55%) showed IgE binding to proteins in wine extracts. The proteins were identified by mass spectrometry as grape-derived vacuolar invertase and thaumatin-like protein. Immunoblot reactivity was closely associated with the presence of IgE to CCDs and was inhibited by preincubation with a glycoconjugate containing bromelain-type N-glycans. The same conjugate, CCD-bearing allergens, and wine extracts activated basophils in patients with high-titer CCD-specific IgE but not in healthy controls. There was no relationship between immunoblot reactivity and consumption of any specific type of wine. No patient reported symptoms of hypersensitivity to Hymenoptera venom, food, or wine. In conclusion, heavy drinkers frequently show IgE reactivity to the N-glycans of wine glycoproteins. Glycans and wine glycoprotein extracts can induce basophil activation in sensitized alcoholics. The clinical significance of these findings remains to be elucidated.

Sensitization to cross-reactive carbohydrate determinants in relation to alcohol consumption.

BACKGROUND: Alcohol consumption is associated with increased serum IgE of unknown specificity. OBJECTIVE: To investigate the prevalence of specific IgE to cross-reactive carbohydrate determinants (CCDs) in adults, and its relation to alcohol consumption. METHODS: Population-based survey of 457 adults (218 abstainers, 195 light-to-moderate drinkers, 44 heavy drinkers). Specific IgE determinations included a CCD (MUXF(3), the N-glycan of bromelain), pollens (Lolium perenne and Olea europaea), Hymenoptera venoms (Apis mellifera and Vespula spp.), and a mite (Dermatophagoides pteronyssinus). We replicated these studies in an additional sample of alcoholics (n=138). Inhibition assays were performed in selected cases. RESULTS: In the general population, 5.6% of individuals (95% confidence interval 3.5-7.6%) showed positive (>/=0.35 kU/L) CCD-specific IgE. The levels of CCD-specific IgE were particularly high in heavy drinkers, who also showed a high prevalence of positive IgE to pollens and Hymenoptera venoms, doubling (at least) the prevalence found in alcohol abstainers and light-to-moderate drinkers. The presence of IgE to pollens and Hymenoptera venoms was closely correlated with the presence of CCD-specific IgE. These features were confirmed in the additional sample of alcoholics. Inhibition studies indicated a role of CCD interference in IgE positivity to pollen and Hymenoptera allergens in alcoholics. CONCLUSIONS: CCD-specific IgE is prevalent in heavy drinkers, and is associated with positive IgE to pollens and Hymenoptera venoms. Specific IgE results should be interpreted with caution in heavy drinkers.

Prevalence and clinical relevance of specific immunoglobulin E to pollen caused by sting- induced specific immunoglobulin E to cross-reacting carbohydrate determinants in Hymenoptera venoms.

BACKGROUND: Hymenoptera stings can induce specific IgE (sIgE) to carbohydrate determinants (CD) on venom glycoproteins that cross-react with CD in pollen. sIgE to such cross-reacting CD (CCD) are believed to have little or no biological activity and thus may cause misdiagnosis of pollen sensitization after a sting. OBJECTIVE: To determine the prevalence of multiple false positive CAP results to pollen because of sting induced anti-CCD sIgE in Hymenoptera venom (HV) allergic patients and to investigate the association of such anti-CCD sIgE with features of 'atopy'. METHODS: Skin prick tests (SPT) and CAP tests with grass, tree and weed pollen and with house dust mite (HDM) were carried out prospectively in 259 HV allergic patients and CAP tests with honeybee (HBV) and yellow jacket (YJV) venom were performed. Patients with negative pollen SPT associated with positive CAP tests to all three pollen groups were operationally defined as 'CCD positive'. We investigated in selected 'CCD positive' patients the presence of anti-CCD sIgE by CAP tests with bromelain and studied the identity of CD in HVs and pollen by mutual sIgE inhibition tests with CD from proteinase treated HBV (HBV-CD) and Lolium perenne (Lol-CD) extracts. RESULTS: sIgE to all three pollen groups without positive SPT or history was found in 16% of 259 patients. The presence of anti-CCD sIgE was substantiated by positive CAP tests with bromelain in 14/14 and by inhibition of all pollen CAP tests with HBV-CD in 8/9 and with Lol-CD in 2/2 patients. Double venom (DV) positive CAP tests were present in 93% of 'CCD positive' patients and were in some associated with DV skin test positivity and allergy. The prevalence of 'CCD positivity' was significantly higher among HBV (23%) than among YJV (11%) allergic patients, but was also unexpectedly high among those with DV allergy (47%). 'CCD positive' patients were younger, had a higher total IgE and more sIgE to HDM than 'CCD negative' patients. CONCLUSION: We have shown that the risk in HV allergic patients for misdiagnosis of multivalent pollen sensitization is 16%, and we have confirmed that sting induced anti-pollen sIgE are directed to similar CD in venoms and pollen. We found evidence that the recognition of CCD might be related to the 'atopic' trait. Importantly, a positive bromelain CAP test does not exclude clinical reactivity to both venoms in 'CCD positive' HV allergic patients.

Allergen-stimulated T lymphocytes from allergic patients induce vascular cell adhesion molecule-1 (VCAM-1) expression and IL-6 production by endothelial cells.

Adhesion of inflammatory cells to endothelium is a critical step for their transvascular migration to inflammatory sites. To evaluate the relationship between T lymphocytes (TL) and vascular endothelium, supernatants from allergen-stimulated TL obtained from patients sensitive to Dermatophagoides pteronyssinus (Dpt) versus healthy subjects were added to endothelial cell (EC) cultures. TL were stimulated by autologous-activated antigen-presenting cells (APC) previously fixed in paraformaldehyde to prevent monokine secretion. Two parameters were measured: the expression of adhesion molecule and the production of IL-6. Related allergen-stimulated TL supernatants from allergic patients induced an increase of VCAM-1 and intercellular adhesion molecule-1 (ICAM-1) expression when supernatants of the control groups (TL exposed to an unrelated allergen or not stimulated or TL obtained from healthy subjects) did not. E-selectin expression was not modulated whatever the supernatant added to EC culture. IL-6 production by EC was significantly enhanced after activation with related allergen-stimulated TL supernatants from allergics compared with control supernatants. Induction of VCAM-1 expression was inhibited by adding neutralizing antibodies against IL-4, whereas IL-6 production and ICAM-1 expression were inhibited by anti-interferon-gamma (IFN-gamma) antibodies. Enhanced production of IL-4 and IFN-gamma was detected in related allergen-stimulated TL supernatants from allergic subjects compared with the different supernatants. These data suggest that allergen-specific TL present in the peripheral blood of allergic patients are of Th1 and Th2 subtypes. Their stimulation in allergic patients may lead to the activation of endothelial cells and thereby participate in leucocyte recruitment towards the inflammatory site.

Arthropod envenomations.

Millions of arthropods surround us every day, but only a few are medically harmful. Knowledge of the habits and habitats of known venomous arthropods is certainly advisable for the prudent person in areas of known infestation as a preventive measure. Arthropod envenomations probably produce much less mortality than previously thought, but the potential for severe effects of direct envenomation or allergic response exists with some species, and these events must be approached as true medical emergencies.