EAACI Molecular Allergology User's Guide

The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

Prevalence and risk factors for allergic rhinitis in two resource-limited settings in Peru with disparate degrees of urbanization

BACKGROUND

Allergic rhinitis is a disease with a high global disease burden, but risk factors that contribute to this condition are not well understood.

OBJECTIVE

To assess the prevalence and risk factors of allergic rhinitis in two Peruvian populations with disparate degrees of urbanization.

METHODS

We conducted a population-based, cross-sectional study on 1441 children aged 13-15 years at enrollment (mean age 14.9 years, 51% boys) to investigate the prevalence of allergic disease. We used a standardized, Spanish validated questionnaire to determine the prevalence of allergic rhinitis and asked about sociodemographics and family history of allergies. Children also underwent spirometry, exhaled nitric oxide, allergy skin testing to 10 common household allergens and provided a blood sample for measurement of 25OH vitamin D and total serum IgE.

RESULTS

Overall prevalence of allergic rhinitis was 18% (95% CI 16% to 20%). When stratified by site, the prevalence of allergic rhinitis was 23% Lima vs. 13% in Tumbes (P < 0.001); however, this difference was no longer significant after controlling for subject-specific factors (P = 0.95). There was a strong association with other allergic diseases: 53% of children with asthma had allergic rhinitis vs. 15% in those without asthma (P < 0.001) and 42% of children with eczema vs. 17% of those without eczema (P < 0.001). Important risk factors for allergic rhinitis were parental rhinitis (adjusted OR = 3.0, 95% CI 1.9-4.7 for 1 parent and adjusted OR = 4.4, 95% CI 1.5-13.7 for 2 parents); allergic sensitization to common household aeroallergens (1.6, 1.1-2.3); being overweight (1.5, 1.0-2.3); exhaled nitric oxide ≥ 20 ppb (1.9, 1.3-2.7); and total serum IgE ≥ 95th percentile (2.4, 1.2-4.8). Population attributable risk of important factors for allergic rhinitis were 25% for high exhaled nitric oxide, 22% for allergic sensitization to common household aeroallergens, 22% for paternal rhinitis, 10% for being overweight and 7% for an elevated total serum IgE.

CONCLUSION AND CLINICAL RELEVANCE

Allergic rhinitis was prevalent in both settings, and important risk factors include elevated exhaled nitric oxide, allergic sensitization to common household aeroallergens, parental rhinitis, being overweight and high total serum IgE. When considering subject-specific factors, the difference in prevalence between the urban and rural settings became non-important.

Cat allergen-induced blood basophil reactivity in vitro predicts acute human nasal allergen challenge responses in vivo

BACKGROUND

Basophil histamine release (BHR) to allergen has been used as a confirmatory test to support the clinical diagnosis of allergic disease.

OBJECTIVE

Among subjects reporting respiratory cat allergy, we hypothesized that cat-induced BHR in vitro would predict nasal allergen challenge (NAC) response in that same individual. We therefore compared the magnitude of cat allergen-induced BHR to NAC outcome and serological measures of cat-specific IgE and the ratio of cat-specific IgE to total IgE.

METHODS

Forty-two subjects with a history of cat allergy, positive cat puncture skin test (PST) and detectable cat-specific IgE (> 0.1 kAU/L, ImmunoCap) participated with consent. Subjects were grouped as positive or negative cat allergen-induced BHR, with a positive result defined as the release of ≥ 20% of the total cellular histamine content. The majority of subjects also underwent a NAC with a positive result defined as ≥ 5 total sneezes.

RESULTS

Subjects with a positive compared with a negative cat allergen BHR had higher cat-specific IgE levels at 5.40 ± 1.24 kAU/L (n=25) vs. 1.55 ± 0.73 kAU/L (n=17, P=0.01) as well as a higher cat-specific IgE/total IgE ratio [6.1 ± 1.4% (n=25) vs. 1.6 ± 0.9% (n=17, P=0.01)]. Of the 31 subjects who underwent a NAC, a positive NAC was observed in 78% (18/23) with a positive cat allergen BHR compared with 37% (3/8) with a negative cat allergen BHR, giving a positive predictive value of 78% and a negative predictive value of 63%. The diagnostic sensitivity and specificity of a positive BHR to predict a positive NAC was 86% and 50%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

A positive cat allergen-induced BHR is associated with higher cat-specific IgE levels, a higher cat-specific to total IgE ratio and is predictive of a positive cat-induced NAC [ClinicalTrials.gov NCT00604786].

Subcutaneous allergen immunotherapy restores human dendritic cell innate immune function

BACKGROUND

We recently reported that human blood dendritic cells from allergic subjects have impaired IFN-alpha production following toll-like receptor 9 (TLR9)-dependent innate immune stimulation. It is not known how subcutaneous allergen immunotherapy (SCIT) affects dendritic cell immune responses.

OBJECTIVE

The aim of this study is to determine how SCIT affects human dendritic cell function.

METHODS

Peripheral blood mononuclear cell (PBMC) and plasmacytoid dendritic cells (pDCs) were isolated from the blood of seven dust mite allergic subjects at baseline and upon reaching a standard SCIT maintenance dose that included dust mite and other aeroallergens. Cells were stimulated with various adaptive and innate immune receptor stimuli, or media alone for 20 h with secreted cytokine levels determined by ELISA. A portion of the cells were used to measure intracellular signalling proteins by flow cytometry. Humoral immune responses were measured from plasma.

RESULTS

SCIT resulted in a threefold increase in PBMC production of IFN-alpha in response to CpG at 100 nM (P=0.015) and at 500 nM (P=0.015), n=7. The predominant cell type known to produce IFN-alpha in response to CpG (CpG ODN-2216) and other TLR9 agonists is the pDC. As expected, a robust innate immune response from isolated pDCs was re-established among allergic subjects undergoing SCIT resulting in a fivefold increase in IFN-alpha production in response to CpG at 500 nM (P=0.046), n=7. In contrast, IL-6 production was unaffected by SCIT (P=0.468). Consistent with published reports, IgG4 blocking antibody increased 10-fold with SCIT (P=0.031), n=7. There was no significant increase in the frequency of pDCs or the expression of TLR9 that would account for the rise in IFN-alpha production.

CONCLUSIONS

Allergen immunotherapy increases dendritic cell TLR9-mediated innate immune function, which has previously been shown to be impaired at baseline in allergic subjects.

Identification of clinically relevant cross-sensitization between Soliadgo virgaurea (goldenrod) and Hevea brasiliensis (natural rubber latex)

BACKGROUND

Solidago virgaurea (goldenrod) is a perennial weed from which no allergens have been identified. A high latex content in its leaves has been reported. Although not an airborne allergen, it may be an important occupational sensitizer.

OBJECTIVE

To identify allergenic proteins in goldenrod and to determine whether they cross-react with Hevea brasiliensis latex.

METHODS

Potential cross-reactive allergens in latex and goldenrod were investigated by immunoblot inhibition and ImmunoCAP inhibition analyses using serum from patients with clinically evident goldenrod and/or latex allergy. Cross reactivity between latex allergens and goldenrod proteins was studied using recombinant Hev b 1, 3, 4, 5, 6.01, 6.02, 8, 9, or 11 in ImmunoCAP inhibition analyses.

RESULTS

Immunoglobulin (Ig) E antibodies from individuals with goldenrod allergy bound extracted goldenrod proteins ranging from 20 kDa to 130 kDa in Western blots. Evidence for latex and goldenrod cross reactivity was identified by ImmunoCAP and immunoblot inhibition experiments using serum from patients with strongly positive concomitant latex and goldenrod-specific IgE antibody responses. Observed latex-goldenrod cross reactivity could not be ascribed to any of the recombinant major latex allergens evaluated.

CONCLUSIONS

H brasiliensis latex and goldenrod contain cross-reactive and unique allergenic proteins. Exposure to goldenrod may sensitize patients to latex and vice versa.

Effect of in vitro aspirin stimulation on basophils in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Basophil activation has been implicated in the pathogenesis of aspirin-exacerbated respiratory disease (AERD). However, a comprehensive analysis of basophil responses to aspirin in terms of mediator release, cytokine secretion and increased expression of surface activation markers has not been performed.

OBJECTIVE

To study the in vitro effects of aspirin on the concurrent release of histamine, leukotriene C4 (LTC4) and IL-4 from human basophils and to also evaluate changes in surface activation markers (CD63, CD69 and CD203c) expressed by these cells.

METHODS

Basophil-enriched cell suspensions from 10 patients with AERD and 10 healthy volunteers were incubated with lysine-aspirin for up to 3 h. Cells were analysed for expression of CD63, CD69 and CD203c using flow cytometry. Cell-free supernatants were evaluated for histamine, and LTC4 release and for IL-4 secretion.

RESULTS

Aspirin-induced expression of CD63, CD69 and CD203c yielded 30%, 80% and 70% sensitivity, respectively, but with poor specificity. There was no significant difference in LTC4 synthesis between groups. None of the patients with AERD (or controls) released IL-4 in response to aspirin. A higher dose of 5 mg/mL aspirin-mediated non-specific effects on basophils.

CONCLUSION

Basophil responses to in vitro aspirin challenge are poor indicators of clinical sensitivity. Aspirin activates some basophils by means of mechanisms that differ from the classical IgE-mediated pathway. Our study also shows that the use of 27 mm of aspirin (5 mg/mL) by previous investigators causes non-specific basophil activation, thereby eliminating its usefulness in a cell-based diagnostic test for AERD. Evaluation of in vitro basophil activation has low clinical value in identifying aspirin-induced respiratory reactions.

Human blood dendritic cells from allergic subjects have impaired capacity to produce interferon-alpha via Toll-like receptor 9

BACKGROUND

High-affinity IgE receptor (Fc epsilon RI) expression on blood dendritic cells reportedly correlates with serum IgE levels. Our studies demonstrate that plasmacytoid dendritic cells (pDCs) secrete pro-inflammatory cytokines (IL-6, TNF-alpha) following Fc epsilon RI stimulation - a mode of activation that simultaneously reduces expression of Toll-like receptor 9 (TLR9). Whether or not TLR9 and/or Fc epsilon RI levels and their function on dendritic cells relate to allergic status is unknown.

OBJECTIVE

The aim of this study is to compare the innate (TLR9-mediated) immune response of human pDCs to TLR9 and Fc epsilon RI alpha receptor expression in allergic and non-allergic subjects.

METHODS

Basophil-depleted mononuclear cell fractions containing pDCs were prepared from peripheral blood of allergic and non-allergic subjects. Intracellular TLR9 and surface Fc epsilon RI alpha expression in blood dendritic cell antigen-2-positive cells were determined by flow cytometry. Activating anti-IgE antibody, anti-Fc epsilon RI alpha antibody, and TLR9 agonist were used to stimulate cell suspensions, with cytokine levels determined by ELISA.

RESULTS

No difference in the frequency of pDCs was detected among allergic (n=9) vs. non-allergic (n=11) subjects (P=0.261). While there was also no difference in the baseline expression of TLR9, pDCs from allergic subjects produced sixfold less IFN-alpha when stimulated with CpG (P=0.002). Conversely, there was higher Fc epsilon RI alpha expression (P=0.01) on the pDCs of allergic subjects.

CONCLUSIONS

Impaired TLR9-dependent immune responses in human pDCs are associated with allergic status and inversely correlated with Fc epsilon RI alpha expression. This impaired innate immune response among dendritic cells of allergic subjects may lead to more targeted therapeutic approaches and could provide a better understanding of the mechanisms underlying conventional and CpG-based immunotherapy.

Quantitative analysis of immunoglobulin E reactivity profiles in patients allergic or sensitized to natural rubber latex (Hevea brasiliensis)

BACKGROUND

Characterized native and recombinant Hevea brasiliensis (rHev b) natural rubber latex (NRL) allergens are available to assess patient allergen sensitization profiles.

OBJECTIVE

Quantification of individual IgE responses to the spectrum of documented NRL allergens and evaluation of cross-reactive carbohydrate determinants (CCDs) for more definitive diagnosis.

METHODS

Sera of 104 healthcare workers (HCW; 51 German, 21 Portuguese, 32 American), 31 spina bifida patients (SB; 11 German, 20 Portuguese) and 10 Portuguese with multiple surgeries (MS) were analysed for allergen-specific IgE antibody (sIgE) to NRL, single Hev b allergens and CCDs with ImmunoCAP technology.

RESULTS

In all patient groups rHev b 5-sIgE concentrations were the most pronounced. Hev b 2, 5, 6.01 and 13 were identified as the major allergens in HCW and combined with Hev b 1 and Hev b 3 in SB. In MS Hev b 1 displayed an intermediate relevance. Different sIgE antibody levels to native Hevea brasiliensis (nHev b) 2 and rHev b 6.01 allowed discrimination of SB with clinical relevant latex allergy vs. those with latex sensitization. Sensitization profiles of German, Portuguese and American patients were equivalent. rHev b 5, 6.01 and nHev b 13 combined detected 100% of the latex-allergic HCW and 80.1% of the SB. Only 8.3% of the sera showed sIgE response to CCDs.

CONCLUSIONS

Hev b 1, 2, 5, 6.01 and 13 were identified as the major Hev b allergens and they should be present in standardized latex extracts and in vitro allergosorbents. CCDs are only of minor relevance in patients with clinical relevant latex allergy. Component-resolved diagnostic analyses for latex allergy set the stage for an allergen-directed immunotherapy strategy.

Latex allergy: low prevalence of immunoglobulin E to highly purified proteins Hev b 2 and Hev b 13

BACKGROUND

Hevea brasiliensis (Hev b) 2 and Hev b 13 have recently been identified as major latex allergens by detecting specific IgE antibodies in >50% of sera from Hev b latex-allergic individuals.

OBJECTIVE

We assessed the prevalence rates for sensitization to extensively purified latex allergens in patients from three diverse geographical areas.

METHODS

Native Hev b 2, Hev b 5, Hev b 6.01 and Hev b 13 were purified by non-denaturating chromatography and were used in ELISAs to assess sera from 215 latex-allergic patients and 172 atopic non-sensitized controls from Finland, Spain and the United States to detect allergen-specific IgE antibodies.

RESULTS

Unexpectedly, even highly purified Hev b 13 contained epitope(s) to which Hev b 6-specific human IgE antibodies bound effectively. Further purification, however, reduced the prevalence of IgE antibody reactivity to low levels: 15%, 5% and 11% for Hev b 2, and 18%, 30% and 27% for Hev b 13 among latex-allergic Finnish, Spanish and American patients, respectively. Interestingly, Finnish patients had a lower prevalence of Hev b 5-specific IgE antibody (28%) as compared with Spanish (49%) and American (71%) patients. The prevalence of Hev b 6.01-specific IgE reactivity was uniformly >50% in all three populations.

CONCLUSION

Neither Hev b 2 nor Hev b 13 appear to be major latex allergens when evaluated in serological assays using highly purified allergens. The reason(s) for the observed differences in published sensitization rates in various geographic regions requires further study. The purity of the allergen preparations has a marked impact on the accuracy of latex-specific IgE antibody detection in epidemiological studies and in the serological diagnosis of latex allergy.

Percutaneous reactivity to natural rubber latex proteins persists in health-care workers following avoidance of natural rubber latex

BACKGROUND

Long-term avoidance of natural rubber latex [Hevea brasiliensis (Hev b)] is currently recommended for health-care workers (HCWs) with established natural rubber latex (NRL) allergy. Percutaneous sensitivity to eight Hev b NRL allergens was evaluated in HCWs in 2000. To date, no studies have evaluated the longitudinal effects of NRL avoidance on percutaneous sensitivity to NRL allergens.

OBJECTIVE

The aims of this study were to evaluate changes in percutaneous reactivity to non-ammoniated latex (NAL) and NRL allergens in HCWs 5 years after a recommendation to avoid NRL and to evaluate factors that predict the persistence of in vivo sensitivity to NAL and NRL allergens.

METHODS

Skin prick testing was performed with NAL, seven NRL allergens (Hev b 1, 2, 3, 4, 6.01, 7.01, and 13), and recombinant Hev b 5 (rHev b 5) in 34 HCWs who were initially evaluated in 2000 for occupationally related NRL allergy. Serial 10-fold dilutions of NAL and NRL allergens were employed in skin testing. Sera from the HCWs were assayed for latex and enhanced latex (rHev b 5-enriched allergosorbent)-specific IgE antibodies using the ImmunoCAP assay.

RESULTS

The prevalence of work-related symptoms significantly decreased between 2000 and 2005 with avoidance of NRL (P<0.05). A >/=100-fold reduction in percutaneous sensitivity to Hev b 2 and Hev b 7 was less likely in those with prior history of systemic reactions to NRL (P=0.0053), reported history of reaction to cross-reactive foods (P=0.014), continued local reactions to NRL gloves (P<0.0001), or high NRL glove exposure since the initial study (P=0.0075). The diagnostic sensitivity and specificity of the latex-specific IgE serology was 54% and 87.5%, respectively, in comparison with NAL skin tests. The addition of rHev b 5 to the ImmunoCAP (enhanced latex) allergosorbent altered the diagnostic sensitivity and specificity of the ImmunoCAP to 77% and 75%, respectively.

CONCLUSION

While symptoms may resolve quickly with NRL avoidance therapy, detectable IgE indicating continued sensitization remains beyond 5 years, and thus continued avoidance of NRL should be recommended.

Allergen concentration in natural rubber latex

BACKGROUND

Hevea brasiliensis latex serum is commonly used as the in vivo and in vitro reference antigen for latex allergy diagnosis as it contains the full complement of latex allergens.

OBJECTIVE

This study quantifies the concentrations of the significant allergens in latex serum and examines its suitability as an antigen source in latex allergy diagnosis and immunotherapy.

METHODS

The serum phase was extracted from centrifuged latex that was repeatedly freeze-thawed or glycerinated. Quantitation of latex allergens was performed by two-site immunoenzymetric assays. The abundance of RNA transcripts of the latex allergens was estimated from the number of their clones in an Expressed Sequence Tags library.

RESULTS

The latex allergens, Hev b 1, 2, 3, 4, 5, 6, 7 and 13, were detected in freeze-thawed and glycerinated latex serum at levels ranging from 75 (Hev b 6) to 0.06 nmol/mg total proteins (Hev b 4). Hev b 6 content in the latex was up to a thousand times higher than the other seven latex allergens, depending on source and/or preparation procedure. Allergen concentration was reflected in the abundance of mRNA transcripts. When used as the antigen, latex serum may bias the outcome of latex allergy diagnostic tests towards sensitization to Hev b 6. Tests that make use of latex serum may fail to detect latex-specific IgE reactivity in subjects who are sensitized only to allergens that are present at low concentrations.

CONCLUSION

Latex allergy diagnostics and immunotherapy that use whole latex serum as the antigen source may not be optimal because of the marked imbalance of its constituent allergens.

Molecular cloning and immunoglobulin E reactivity of a natural rubber latex lecithinase homologue, the major allergenic component of Hev b 4

BACKGROUND

Hev b 4 is an allergenic natural rubber latex (NRL) protein complex that is reactive in skin prick tests and in vitro immunoassays. On SDS-polyacrylamide gel electrophoresis (SDS-PAGE), Hev b 4 is discerned predominantly at 53-55 kDa together with a 57 kDa minor component previously identified as a cyanogenic glucosidase. Of the 13 NRL allergens recognized by the International Union of Immunological Societies, the 53-55 kDa Hev b 4 major protein is the only candidate that lacks complete cDNA and protein sequence information.

OBJECTIVE

We sought to clone the transcript encoding the Hev b 4 major protein, and characterize the native protein and its recombinant form in relation to IgE binding.

METHODS

The 5'/3' rapid amplification of cDNA ends method was employed to obtain the complete cDNA of the Hev b 4 major protein. A recombinant form of the protein was over-expressed in Escherichia coli. The native Hev b 4 major protein was deglycosylated by trifluoromethane sulphonic acid. Western immunoblots of the native, deglycosylated and recombinant proteins were performed using both polyclonal antibodies and sera from latex-allergic patients.

RESULTS

The cDNA encoding the Hev b 4 major protein was cloned. Its open reading frame matched lecithinases in the conserved domain database and contained 10 predicted glycosylation sites. Detection of glycans on the Hev b 4 lecithinase homologue confirmed it to be a glycoprotein. The deglycosylated lecithinase homologue was discerned at 40 kDa on SDS-PAGE, this being comparable to the 38.53 kDa mass predicted by its cDNA. Deglycosylation of the lecithinase homologue resulted in the loss of IgE recognition, although reactivity to polyclonal rabbit anti-Hev b 4 was retained. IgE from latex-allergic patients also failed to recognize the non-glycosylated E. coli recombinant lecithinase homologue.

CONCLUSION

The IgE epitopes of the Hev b 4 lecithinase homologue reside mainly in its carbohydrate moiety, which also account for the discrepancy between the observed molecular weight of the protein and the value calculated from its cDNA.

Receiver operating characteristics analyses of Food and Drug Administration-cleared serological assays for natural rubber latex-specific immunoglobulin E antibody

Receiver operating characteristics (ROC) analyses to evaluate and compare the diagnostic accuracy of Food and Drug Administration (510K)-cleared natural rubber latex (NRL)-specific immunoglobulin E (IgE) antibody immunoassays have not been performed using well-characterized skin-testing reagents. Sera were collected from 311 subjects (131 latex puncture skin test [PST] positive and 180 PST negative). All masked, coded sera were analyzed for latex-specific IgE antibodies in the Diagnostic Products Corporation microplate AlaSTAT, HYCOR HY-TEC RAST, and Pharmacia-Upjohn CAP System RAST FEIA (CAP). Diagnostic accuracy was evaluated using GraphRoc for Windows software to construct and analyze ROC curves in relation to the subjects' PST status and the results of the immunoassays. The ROC areas under the curve (AUCs) +/- standard error based on PST for the three diagnostic tests were 0.858 +/- 0.024, 0.869 +/- 0.024, and 0.924 +/- 0.017, respectively, for AlaSTAT, CAP, and HY-TEC. The HY-TEC system had a significantly greater AUC based on PST than those observed for AlaSTAT (P < 0.05) and CAP (P < 0.05) analyses. When the diagnostic tests were probed as to the cutoffs giving maximal diagnostic efficiency compared to PST, CAP and AlaSTAT yielded values of <0.35 kU of allergen IgE (kU(A))/liter and <0.35 kU/liter while the HY-TEC assay yielded 0.11 kU/liter. The diagnostic efficiencies based on PST in our cohort at these cutoffs were 87.1, 88.1, and 88.7%, respectively. The HY-TEC assay had a significantly greater AUC than CAP and AlaSTAT using PST as a diagnostic discriminator in our cohort. When the HY-TEC system was probed at its maximally efficient cutoff (0.11 kU/liter) versus HYCOR's recommended cutoff of 0.05 kU/liter, a loss of sensitivity of 8.4% was observed with a gain in specificity of 19.5%.

Cross-Reactivity studies of gutta-percha, gutta-balata, and natural rubber latex (Hevea brasiliensis)

Gutta-percha and gutta-balata are derived from the Paliquium gutta and Mimusops globsa trees, respectively, that are in the same botanical family as the rubber tree Hevea brasiliensis. For this reason the potential for immunological cross-reactivity between the gutta-percha and gutta-balata used in endodontics and natural rubber latex (NRL) has been the subject of some controversy, because these products may be used in latex-allergic individuals. The objective of this study was to investigate the potential cross-reactivity between gutta-percha, gutta-balata, and NRL. Physiological extracts of seven commercially available gutta-percha products, raw gutta-percha, raw gutta-balata, and synthetic transpolyisoprene were each analyzed for cross-reactivity with NRL in a competitive radioallergosorbent test inhibition assay. No detectable cross-reactivity was observed with any of the raw or clinically used gutta-percha products. In contrast the raw gutta-balata released proteins that were cross-reactive with Hevea latex. We conclude that the absence of gutta-percha proteins that can react with Hevea latex-specific IgE antibody supports the minimal potential for commercially available gutta-percha to induce allergic symptoms in individuals sensitized to NRL. Because gutta-balata is sometimes added to commercial gutta-percha products caution should be exercised if products containing gutta-balata are used in endodontic care of latex-allergic individuals.

Repeated latex aeroallergen challenges employing a hooded exposure chamber: safety and reproducibility

BACKGROUND

Bronchial, nasal, and conjunctival challenges are useful for clarifying discordant clinical history (Hx) and skin and/or serologic tests and in assessing semiquantitative changes in biologic sensitivity over time. The objective of this study was to determine the safety and reproducibility of repeated latex-allergen challenges with a hooded exposure chamber (HEC).

METHODS

The HEC system comprises a powered forced-air respirator with a fitted face shield and hood that uses glove-derived latex-allergen associated cornstarch particles (LAC) to expose simultaneously the conjunctiva, nose, and lungs. Serial control and incremental LAC challenges are conducted until an endpoint based on upper and/or lower respiratory tract symptoms and peak expiratory flow rates is reached. Six latex-allergic (Hx and puncture skin test [PST]- and 5/6 radioallergosorbent test [RAST]-positive) subjects were challenged on three separate occasions at least 2 weeks apart. Serial latex PST midpoints and serum anti-latex IgE by RAST were monitored at each visit and at a fourth follow-up visit.

RESULTS

All subjects responded to LAC, but not to air or control cornstarch administered as controls. All responses were confined to mild symptoms of allergic rhinoconjunctivitis and/or asthma that either resolved spontaneously or were reversed with inhaled albuterol. No subject experienced a systemic or delayed reaction. There were no significant changes in the endpoint LAC doses over the three challenge visits (P>0.2). The mean coefficient of variation for log2 endpoints within-subjects was 17.3+/-17.2% (SD). The serum latex-specific IgE was not significantly boosted by the three challenges (P>0.2). The concentration of latex extract necessary to produce an 8-mm wheal by PST was not significantly changed during the study (P>0.1), indicating that latex sensitivity was not affected by the repeated LAC exposures.

CONCLUSIONS

The results of this study indicate that repeated HEC latex-allergen challenges are both reproducible and safe, and do not increase latex sensitivity.

Case report of venom immunotherapy for a patient with large local reactions

BACKGROUND

Inadvertent Hymenoptera stings reportedly elicit large local reactions in up to 17% of the general population. Current practice parameters do not recommend venom immunotherapy (IT) for these cases.

OBJECTIVE

The goal of this case study was to investigate the clinical and immunologic consequences of venom IT in a newly sensitized individual with large local reactions using an intentional sting challenge before and after treatment to document changes in reaction severity.

METHODS

A 47-year-old man became honeybee venom (HBV)-allergic with progressively larger reactions at honeybee sting sites with subsequent stings. Then, a sting on his forefinger produced a large (62 cm) local reaction with swelling throughout the arm that persisted for more than 4 weeks with severe pain. He refused steroid therapy and voluntarily requested venom IT with honeybee-sting challenges to monitor clinical parameters and immunologic changes in his skin and serum before and 7 months post-HBV maintenance IT.

RESULTS

A single pre-IT bee sting challenge produced an 11.4-cm wheal with 13-cm erythema at the sting site after 15 minutes, followed by several weeks of edema that involved the entire arm. After rapid escalation of venom IT to maintenance in 7 weeks, a post-maintenance IT sting challenge with two honeybees produced a 3-cm diameter erythema with no wheal at 15 minutes and no late-phase induration. Complete loss of any visible reaction at the field sting site resulted after 13 months of maintenance venom IT. A HBV-specific IgG antibody level >3.5 microg/mL and IgG/IgE antibody molar ratio >500 persisted over the period of venom IT, with venom skin reactivity diminishing 100-fold.

CONCLUSIONS

These results support venom IT use in the treatment of Hymenoptera venom-sensitive individuals who experience large local reactions and are at risk for repetitive inadvertent stings.

Natural rubber pharmaceutical vial closures release latex allergens that produce skin reactions

BACKGROUND

The release of allergenic proteins from natural rubber vial closures (stoppers) into aqueous pharmaceuticals may induce allergic reactions in individuals with latex allergy (LA) receiving medications from such vials.

OBJECTIVE

The goal of this study was to determine whether solutions stored in vials containing natural rubber closures release allergenic proteins detectable by skin testing of subjects with LA.

METHODS

Five pharmaceutical vial closures (2 natural rubber and 3 synthetic) were coded, inserted onto vials containing phenol-saline-human serum albumin, and stored in an inverted position before use. Twelve volunteers with and 11 volunteers without LA underwent skin testing with solutions from each of the 5 vials, either those not punctured (0P) or those punctured 40 times with a 21-gauge needle 12 to 24 hours before testing (40P).

RESULTS

All intradermal skin test responses in the group without LA were negative. Two and 5 of the 12 subjects with LA had positive intradermal skin reactions to 0P and 40P solutions, respectively, from vials containing rubber closures. Two subjects with LA had inexplicable, positive, nonreproducible intradermal skin test reactions to solutions from vials containing bromobutyl but not vials with isoprene synthetic closures. In vitro inhibition analysis detected 6 to 7 AU/g latex allergen in extracts of cut natural rubber containing closures but not in extracts of synthetic closures.

CONCLUSION

Natural rubber vial closures released allergenic latex proteins into the tested solutions in direct contact during storage in sufficient quantities to elicit positive intradermal skin reactions in some individuals with LA. These data support a recommendation to eliminate natural rubber from closures of pharmaceutical vials.

Allergen-induced changes in airway responsiveness are not related to indices of airway edema

BACKGROUND

The mechanisms behind airway hyperresponsiveness in asthma are unknown. Airway wall edema has been proposed as one possible culprit of this phenomenon.

OBJECTIVE

To test the hypothesis that airway edema may be the cause of allergen-induced increases in airway responsiveness in asthma, this trial aimed at determining the relationship between allergen-induced changes in airway responsiveness to inhaled methacholine and indirect indices of edema, namely peripheral airway resistance and the levels of the plasma protein fibrinogen in bronchoalveolar lavage (BAL) fluids.

METHODS

Twenty-six atopic individuals with mild asthma were subjected to bronchoscopy at baseline and 28 hours after allergen inhalation. Before each bronchoscopy, methacholine bronchoprovocation was performed. During bronchoscopy, peripheral airway resistance measurements were obtained by wedged bronchoscopy. BAL fluids were analyzed for fibrinogen, as well as for eosinophilic cationic protein. Cytology was performed, and cytokine gene expression was assessed with competitive reverse transcriptase PCR from cell pellets.

RESULTS

A significant increase in airway responsiveness to methacholine was recorded after allergen, but this did not correlate with changes in peripheral airway resistance (which was not affected) or with BAL fibrinogen (which decreased after allergen). Other BAL outcomes confirmed that airway inflammation was produced and was characterized by a T(H)2 cytokine pattern.

CONCLUSIONS

Airway responsiveness in asthma increases after exposure to allergen in the absence of increased indirect indices of edema. The role of edema in this phenomenon should therefore be tested more vigorously.

Insect sting allergy with negative venom skin test responses

BACKGROUND

In our 1976 controlled venom immuno rapy trial, 33% of 182 patients with a history of systemic reactions to insect stings were excluded because of negative venom skin test responses. There have been reports of patients with negative skin test responses who have had severe reactions to subsequent stings.

OBJECTIVE

Our aim is to increase awareness about the patient with a negative skin test response and insect sting allergy and to determine the frequency and significance of negative skin test responses in patients with a history of systemic reactions to insect stings.

METHODS

We prospectively examined the prevalence of negative venom skin test responses in patients with a history of systemic reactions to stings. In patients who gave informed consent, we analyzed the outcome of retesting and sting challenge.

RESULTS

Of 307 patients with positive histories screened for our sting challenge study, 208 (68%) had positive venom skin test responses (up to 1 microg/mL concentration), and 99 (32%) had negative venom skin test responses. In 36 (36%) of the 99 patients with negative skin test responses, the venom RAST result was a low positive (1-3 ng/mL), or repeat venom skin test responses were positive; another 7 (7%) patients had high venom-specific IgE antibody levels (4-243 ng/mL). Notably, 56 (57%) of 99 patients with positive histories and negative skin test responses had negative RAST results. In patients with positive skin test responses, sting challenges were performed in 141 of 196 patients, with 30 systemic reactions. Sting challenges were performed on 37 of 43 patients with negative skin test responses and positive venom-specific IgE and in 14 of 56 patients with negative skin test responses and negative RAST results. There were 11 patients with negative skin test responses who had systemic reactions to the challenge sting: 2 had negative RAST results, and 9 had positive RAST results at 1 ng/mL. The frequency of systemic reaction was 21% in patients with positive skin test responses and 22% in patients with negative skin test responses (24% in those with positive RAST results and 14% in those with negative RAST results).

CONCLUSIONS

Venom skin test responses can be negative in patients who will subsequently experience another systemic sting reaction. Venom skin test responses are negative in many patients with a history of systemic allergic reactions to insect stings and may be associated with positive serologic test responses for venom-specific IgE antibodies (sometimes strongly positive results). Venom skin test responses should be repeated when negative, along with a serologic IgE antivenom test. Better diagnostic skin test reagents are urgently needed.

Asthma severity, atopic status, allergen exposure and quality of life in elderly persons

BACKGROUND

Although asthma can be associated with significant airflow obstruction in those over the age of 65, it is often underdiagnosed and undertreated.

OBJECTIVE

To describe severity of asthma, allergy skin test sensitivities, indoor allergen exposures, and the impact on quality of life (QOL) and health status in elderly persons with asthma.

METHODS

A cross-sectional data analysis with 80 elderly persons with asthma recruited from medical, geriatric, and allergy/immunology tertiary care centers. Asthma severity was determined by symptoms and measurements of lung function. House dust specimens were collected from mattresses and bedroom carpets and analyzed separately for the major allergens of house dust, using monoclonal antibody-based immunoenzymetric assays. QOL was measured using Juniper's Asthma Quality of Life Questionnaire. Health status was measured using the Short Form Health Survey Medical Outcome Questionnaire which included Ferrans and Powers' Quality of Life Index subscales.

RESULTS

Two-thirds of participants had either moderate or severe persistent asthma. Skin tests to a battery of common airborne allergens were positive to at least one allergen in 56 of the 75 participants tested (74.7%). Reservoir dust allergen levels were often high enough to place participants at risk of symptoms or at risk of developing sensitization. Increased asthma severity was associated with significantly lower QOL and a trend toward decreased health status.

CONCLUSIONS

Asthma is a significant chronic problem in the elderly. Atopy was common. Asthma severity impacts on these participants' QOL and health status. Results support interventions aimed at identifying allergens precipitating attacks and reducing them in the home.

Absence of immunopathology associated with repeated IV administration of bovine Hb-based oxygen carrier in dogs

BACKGROUND

A Hb-based oxygen carrier, HBOC-301, is licensed by the FDA for use as a single-dose product to treat anemia in canines. The objective of this study was to investigate the immunopathologic consequences of multiple doses of HBOC-301.

STUDY DESIGN AND METHODS

HBOC-301 was administered intravenously at 1.3 g per kg (10 mL/kg) nine times over 50 weeks to each of eight splenectomized beagles. During interim weeks, HBOC-301-specific IgG antibody was quantified in serum by immunoassay. Immunofluorescence studies were performed on thin sections of control and test dog livers and kidneys to detect any IgG, IgM, IgA, or C3 deposition. Physiology (p50) studies evaluated the capacity of circulating HBOC-301-specific IgG antibody to competitively block the binding of oxygen to HBOC-301.

RESULTS

HBOC-301-specific IgG antibody was detected in seven of eight HBOC-301-treated dogs by Week 6. Peak antibody levels occurred by Week 10 (after the third dose). Immunofluorescence studies detected comparable IgG, IgA, IgM, or C3 deposition patterns in the kidneys and livers of both control and test dogs, which indicated no selective antibody-mediated deposition from multiple HBOC-301 administrations. Moreover, HBOC-301-specific IgG antibody in serum was unable to inhibit oxygen binding to the HBOC-301 in vitro, which indicated that circulating antibody did not diminish the oxygen-binding capacity of HBOC-301.

CONCLUSION

The immunologic, histologic, and physiologic data support the safety of multidose administration of HBOC-301 in canines.

Antigen-specific IgE and IgA antibodies in bronchoalveolar lavage fluid are associated with stronger antigen-induced late phase reactions

The mechanism(s) leading to the development of late phase allergic reactions is (are) unknown. Previous studies have indicated that a relationship between serum IgE and the late phase exists. To explore the relationships between allergen-specific immunoglobulins in bronchoalveolar lavage (BAL) fluids and the magnitude of airflow limitation during the late phase response to inhaled allergen. Ragweed-specific IgE, IgA, secretory IgA (sIgA) and IgG were measured in BAL fluid and in the serum 1-5 weeks before whole lung antigen challenge with ragweed extract, in 16 ragweed allergic asthmatics. In addition, BAL and serum eosinophil cationic protein (ECP) and BAL fibrinogen levels were determined and BAL cells counted and differentiated. The latter procedures were repeated in a second BAL performed 24 h after the end of the ragweed challenge. After the challenge, lung function was monitored hourly for 8 h, to record the magnitude of airflow limitation. Ragweed-specific immunoglobulins were detected in 25% to 37.5% of BAL samples. Compared to the subjects with undetectable BAL fluid ragweed-specific IgE levels at baseline, those with detectable antibodies had stronger late phase reactions as determined by the nadir of FEV1 between hours 4 and 8 after the ragweed inhalation challenge (P = 0.0007). Allergen-induced changes in BAL ECP and fibrinogen levels were also higher in those subjects with detectable ragweed-specific IgE in baseline fluids (P = 0.03 and P = 0.005, respectively). Significant relationships between BAL antigen-specific IgA, serum ragweed-specific IgE and IgA and the late phase reaction were also found. The results of this study point towards the possibility that allergen-specific IgE and IgA may be independently involved in the pathogenesis of the late phase reaction. This notion merits further exploration.

House dust mite and cockroach exposure are strong risk factors for positive allergy skin test responses in the Childhood Asthma Management Program

BACKGROUND

Children with asthma have a high prevalence of environmental allergies, especially to indoor allergens. The relationships of exposure to indoor allergens (dust mites, cat, dog, cockroach, and molds) and other host factors to allergy sensitization have not been evaluated simultaneously in a large cohort.

OBJECTIVES

We studied 1041 children aged 5 to 12 years with mild-to-moderate asthma to determine risk factors associated with having positive allergy skin test responses to indoor allergens. Also, we described, compared, and contrasted 6 allergens in the home environments of these children from 8 North American cities.

METHODS

Data were used from baseline visits of the Childhood Asthma Management Program. Patients' sensitivities to house dust mites (Dermatophagoides farinae and Dermatophagoides pteronyssinus), cats, dogs, cockroaches, and molds were examined for relationships to demographic variables, home dust allergen exposures, number of other positive allergy skin test responses, total serum IgE levels, and smoking in the home.

RESULTS

San Diego (78.5%) and Toronto (59.3%) had the topmost percentages of homes with moderate-to-high house dust mite levels. Boston (21.5%), St Louis (16.3%), and Baltimore (13.4%) had the highest percentages of homes with detectable levels of cockroach allergen. For house dust mites, the higher the level of allergen exposure, the more likely patients were to have positive allergy skin test responses, with relative odds of 9.0 (95% confidence interval, 5.4-15.1) for those exposed to high mite levels (>10.0 microg/g dust) relative to those unexposed. Even exposure to low levels of mite allergen (0.020-2.0 microg/g) was found to be a significant risk factor for sensitization. For cockroach allergen, those with detectable home exposure were more likely to have positive skin test responses (relative odds, 2.2; 95% confidence interval, 1.3-3.8) than those with undetectable exposure. In contrast, levels of exposure to cat, dog, and mold allergens were not related to sensitization rates. For cat allergen, this may reflect lower rates of cat ownership among highly sensitized subjects. Furthermore, the number of allergy skin test responses that were positive, excluding the test for the outcome of interest for each model, and total serum IgE levels were strong independent predictors of sensitization.

CONCLUSIONS

Levels of exposure determined by house dust analysis are important determinants of sensitization for dust mite and cockroach allergen. This relationship was not demonstrable for cat, dog, or mold allergens, possibly because of confounding factors. For all allergens studied, the degree of atopy, determined by the total number of positive skin test responses or by total serum IgE levels, is an important contributing risk factor for sensitization.

A hooded exposure chamber method for semiquantitative latex aeroallergen challenge

BACKGROUND

Allergen challenges are useful in adjudicating discordant clinical histories and skin test responses, serologic test responses, or both, as well as in determining the degree of allergic reactivity. Latex allergen challenges have been developed but have limitations that reduce their usefulness.

OBJECTIVE

We sought to develop a novel hooded exposure chamber (HEC) system to allow safe, sensitive, and semiquantitative evaluation of respiratory latex allergy.

METHODS

The HEC system uses an impinger to produce a particle cloud of cornstarch isolated from powdered latex gloves. The particles are air driven into a face shield and hood to simultaneously challenge the subject's conjunctiva, nose, and lungs during 3 minutes of normal tidal breathing. A cloud of respirable latex allergen-associated cornstarch particles (LACs) is consistently produced in the HEC during challenges. Twenty-three subjects with latex allergy (history and positive skin test response, positive serologic test response, or both) and 3 atopic control subjects not allergic to latex (history and negative skin test response, negative serologic test response, or both) were sequentially exposed to air, control cornstarch, and then progressive 2-fold increments of LACs in a single-masked fashion. A positive challenge result was defined as (1) a peak expiratory flow rate decline of 15% or greater from baseline; (2) a peak expiratory flow rate decline of 10% or greater and an increase of either the rhinoconjunctivitis or chest symptom score scale of 3 or more points from baseline; or (3) an increase of either the rhinoconjunctivitis or chest symptom score scale of 6 or more points from baseline.

RESULTS

Twenty-two of the 23 subjects with latex allergy reached threshold criteria for a positive challenge at LAC titers of 1:8 or greater, giving a sensitivity of 0.96. Challenge endpoints were moderately corrected with skin test sensitivity (r (s) = -0.55, P =.01) but not with RAST reactivity. None of the 3 control subjects responded to LACs at the 1:8 dilution. No patient or control subject responded to the air or control cornstarch control exposures. All responses were confined to mild symptoms of allergic rhinoconjunctivitis, asthma, or both that either resolved spontaneously or were easily reversed with inhaled albuterol. No subject experienced a systemic or late-phase reaction.

CONCLUSION

The HEC procedure is a safe, sensitive, and specific method for masked semiquantitative latex aeroallergen challenges that mimic occupational latex exposure to powdered latex gloves.

The relationship between serum IgE and surface levels of FcepsilonR on human leukocytes in various diseases: correlation of expression with FcepsilonRI on basophils but not on monocytes or eosinophils

BACKGROUND

Expression of receptors for IgE (FcepsilonR) have been mainly studied on mast cells and blood basophils in the context of allergic disease. Some reports have noted limited expression of FcepsilonR on other leukocytes, including blood monocytes and eosinophils in certain patients. An association between human blood basophil expression of FcepsilonRIalpha and serum IgE has been noted among allergic subjects.

OBJECTIVE

Recent evidence supports regulation of FcepsilonRIalpha by free IgE on both mast cells and basophils. We hypothesized that this relationship would exist across an extremely wide range of IgE levels for human basophils, irrespective of underlying disease. We further examined whether a similar relationship existed between serum IgE and FcepsilonRIalpha or FcepsilonRII (CD23) expression on monocytes and eosinophils in these same subjects.

METHODS

Blood was obtained from nonallergic subjects (n = 3) and subjects with allergic asthma (n = 5), atopic dermatitis (n = 3), hypereosinophilic syndromes (n = 7), hyper-IgE syndrome (n = 6), helminth infestation (n = 6), or IgE myeloma (n = 1). Levels of serum IgE were determined by using RIA and ranged from 3 to 4.7 mg/mL. Levels of cell surface FcepsilonRIalpha, FcepsilonRII, and IgE were measured by using immunofluorescence and flow cytometry.

RESULTS

Basophil surface IgE density and FcepsilonRIalpha expression correlated with serum IgE levels (r = 0. 67 and r = 0.46, respectively; P <.01; n = 31) regardless of the disease state. In contrast, monocyte FcepsilonRIalpha expression did not correlate with serum IgE (r = 0.09, P >.5, n = 29), and low-level eosinophil FcepsilonRIalpha expression was only detected in a single asthmatic subject. CD23 expression was not detected on basophils or eosinophils, except for the eosinophils from the donor with IgE myeloma. CD23 was present on monocytes from some donors but did not correlate with serum IgE levels.

CONCLUSIONS

In a variety of disease states, FcepsilonRIalpha expression by basophils, but not monocytes or eosinophils, correlated with serum IgE levels across a 6-log range of IgE. These data support the concept of in vivo regulation of FcepsilonRIalpha on basophils by serum IgE and further demonstrate that this is independent of allergic disease per se.

Group-specific antibody levels surrounding invasive pneumococcal illness in children infected with human immunodeficiency virus

Pneumococcal antibody levels surrounding systemic pneumococcal illness (SPI) were measured in children infected with human immunodeficiency virus (HIV). Archived serum samples were collected from 28 HIV-infected children who had 34 cases of SPI, caused by pneumococcal groups 4, 6, 9, 14, 19, and 23. Serum samples collected within 23 weeks before and 13 weeks after the SPI were assayed by ELISA for antipneumococcal polysaccharide (PnPs) IgG antibody to 6 representative pneumococcal serotypes. There was a wide range (0. 16-30.80 microg/mL) of pre-SPI anti-PnPs antibody levels to the presumed infecting serotypes, with a geometric mean level of 0.83 microg/mL (n=34). Seventy-six percent of the antibody values were <2.0 microg/mL, and 95% were <5.0 microg/mL. Homologous seroresponses (>/=4-fold rise in anti-PnPs antibody) were detected in only 4 (27%) of 15 paired serum samples. Heterologous, noninfecting group seroresponses were detected frequently (72%) in the paired serum samples from these 4 homologous group seroresponders.

Protamine allergy as a complication of insulin hypersensitivity: A case report

BACKGROUND

Although most patients receiving insulin produce insulin-specific IgE, significant allergic symptoms develop in very few of them. Patients receiving neutral protamine Hagedorn (NPH) insulin are at increased risk for the development of protamine hypersensitivity. The case of a 19-year-old woman with insulin-dependent diabetes and regular and NPH insulin hypersensitivity is presented.

OBJECTIVE

The purpose of this study was to determine whether desensitization to NPH insulin, as well as standard insulin desensitization, could control allergic symptoms in a patient allergic to both NPH and regular insulin.

METHODS

The patient required insulin desensitization for severe urticaria, angioedema, and occasional wheezing resulting from her insulin dose. She underwent a standard protocol for insulin desensitization twice in a 2-month period, with persistence in her symptoms. She was found to have high protamine-specific, as well as insulin-specific, IgE levels, and because of her poor response to regular insulin desensitization, she was desensitized to both regular and NPH insulin.

RESULTS

Dual desensitization resulted in marked improvement in her symptoms. The patient had recurrence of urticaria and angioedema a year and a half later, at which point the NPH was stopped and she was desensitized to regular insulin. She continued to receive regular insulin 4 times per day over the following 3 years with only occasional hives.

CONCLUSION

Patients with insulin allergy may not have complete resolution of their symptoms after standard desensitization, particularly those patients with concomitant protamine allergy. These patients may require protamine/NPH desensitization, an alternative insulin preparation, or both.

Adult onset grape hypersensitivity causing life threatening anaphylaxis

BACKGROUND

Adverse reactions to foods are encountered much less frequently in adults than in the children. Adult onset hypersensitivity to grapes has not been previously reported.

OBJECTIVE

Evaluation of a case of anaphylaxis that occurred as a result of the consumption of white grapes (Vitis vinifera).

METHODS AND RESULTS

A 28-year-old woman experienced generalized urticaria, facial/oropharyngeal angioedema, and dizziness after eating a bunch of white grapes. She was treated in an emergency room for anaphylaxis. Previously, she had experienced two similar episodes after eating white grapes. The grape prick skin tests were strongly positive forming a pseudopod type reaction. The total serum IgE was 1918 ng/mL. The grape-specific serum IgE was weakly positive by the modified RAST and negative in the Pharmacia-Upjohn Cap System.

CONCLUSION

Hypersensitivity to a commonly consumed fruit such as grapes can develop late in life causing a near-fatal anaphylaxis.

A comparison of skin prick tests, intradermal skin tests, and RASTs in the diagnosis of cat allergy

BACKGROUND

Skin testing and RASTs are the most commonly used methods for the diagnosis of allergy. Questions remain, however, as to the accuracy of these tests, particularly with regard to the role of intradermal skin tests (IDSTs) in the evaluation of respiratory allergy.

OBJECTIVE

The purpose of this study was to determine the predictive value of skin prick tests (SPTs), IDSTs, and RASTs in the diagnosis of cat allergy.

METHODS

Patients were challenged with a well-characterized cat exposure model after evaluation by history, SPTs, IDSTs (if SPT results were negative), and RASTs. All patients were evaluated with respect to their upper respiratory responses, although only those patients with asthma were included in the analysis of lower airway responses. Challenge results were considered positive if the mean upper respiratory symptom score was 0.5 or more, the mean lower respiratory symptom score was 0.4 or more, or the maximum fall in FEV1 value was 15% or more.

RESULTS

One hundred twenty patients were evaluated. SPT values were positive in 81 patients; of the remaining 39 patients, IDST values were positive in 26 patients. RASTs were performed in 89 patients; the values were positive in 45 of 51 patients with a positive SPT value and were negative in all patients with a negative SPT value. When any positive challenge outcome was considered, positive challenge results were seen in 38 of 41 patients with a positive SPT score, in 10 of 39 patients with a negative SPT score, in 6 of 26 patients with a positive IDST score, in 4 of 13 patients with a negative IDST score, in 27 of 27 patients with a positive RAST score, and in 12 of 44 patients with a negative RAST score.

CONCLUSION

Although both SPT and RAST values exhibited excellent efficiency in the diagnosis of cat allergy, IDST scores added little to the diagnostic evaluation.

Diagnostic performance of Food and Drug Administration-cleared serologic assays for natural rubber latex-specific IgE antibody. The Multi-Center Latex Skin Testing Study Task Force

BACKGROUND

In the absence of Food and Drug Administration-approved natural rubber latex skin testing reagents, latex-specific IgE antibody immunoassays are used in the diagnosis of latex allergy. Comparative diagnostic performance of these tests has not been definitively determined.

OBJECTIVE

We sought to study the predictive value of available Food and Drug Administration (510K)-cleared latex-specific IgE antibody immunoassays in the diagnosis of latex allergy.

METHODS

Subjects (n = 312) were classified as having a positive (n = 117) or a negative (n = 195) latex allergy history (Hx) or having a positive (n = 131) or a negative (n = 181) puncture skin test (PST) response (Greer reagent). The 14 subjects with a negative Hx and a positive PST response had negative responses to glove provocation testing and thus were considered sensitized but asymptomatic. Sera from 22 subjects were split to evaluate intra-assay variation. All 334 coded sera were analyzed for latex-specific IgE antibodies in the Diagnostic Products Corporation microplate AlaSTAT, Hycor HY-TEC EIA System, and Pharmacia-UpJohn CAP System. Variance and diagnostic performance parameters of each test were computed with 95% confidence intervals in relation to the subjects' Hx and PST status.

RESULTS

Intra-assay concordance of split sera results was 96.0% for all 3 assays, with coefficients of variation of less than 25% and between-assay coefficients of variation of less than 21%. The diagnostic performance of the CAP and AlaSTAT assays were equivalent in comparison with PST results: sensitivity, CAP 76.3% and ALASTAT 73. 3% and specificity, CAP 96.7% and AlaSTAT 97.2% (P = NS). The HY-TEC assay was more sensitive (91.6%) and less specific (73.3%) than the CAP and AlaSTAT assays (P <.001). From 9% to 25% of the sera were discordant, being positive in at least 1, but not all 3, assays.

CONCLUSION

The CAP and AlaSTAT assays produce 24% and 27% of false-negative results, respectively, whereas the HY-TEC produces 27% of false-positive results when compared with the PST.

Diagnosis of natural rubber latex allergy: multicenter latex skin testing efficacy study. Multicenter Latex Skin Testing Study Task Force

BACKGROUND

No characterized diagnostic natural rubber latex skin testing material is licensed for use in the United States.

OBJECTIVE

We have conducted a multicenter clinical skin testing study to document the safety and diagnostic sensitivity and specificity of a candidate Hevea brasiliensis nonammoniated latex (NAL) extract. These data are intended to support the licensing of this reagent for the diagnosis of latex allergy in high-risk populations.

METHODS

Three hundred twenty-four subjects (304 adults and 20 children) were classified by their clinical history as having latex allergy (LA group, 124 adults and 10 children) or having no latex allergy (NLA group, 180 adults and 10 children). All subjects provided blood samples and then received sequential puncture skin tests (PSTs) at 1, 100, or 1000 microg/mL protein with a bifurcated needle and NAL (Greer Laboratories) from Malaysian Hevea brasiliensis (clone 600) sap. A 2-stage glove provocation test was used to clarify latex allergy status of individuals with positive history/negative PST result and negative history/positive PST result mismatches.

RESULTS

Twenty-four subjects (15%) originally designated as having LA on the basis of their initial clinical history were reclassified to the NLA group on the basis of a negative glove provocation test result. Of the 134 subjects with LA, 54 (40%) were highly sensitive to latex, with a positive PST result at 1 microg/mL NAL. The Greer NAL reagent produced a positive PST rate (sensitivity) of 95% and 99% in subjects with LA at 100 microg/mL and 1 mg/mL, respectively. The negative PST rate (specificity) in 190 subjects with a negative history with the NAL extract at 100 microg/mL and 1 mg/mL, was 100% and 96%, respectively. Immediately after the PST, mild systemic reactions (mainly pruritus) were recorded in 16.1 % of the adults in the LA group and 4.4% of the adults in the NLA group. No reactions required treatment with epinephrine. Only mild delayed reactions were observed in 9.6% (LA group) and 2.8% (NLA group) of subjects 24 to 48 hours after PST. Mean wheal and erythema diameters measured in the 10 children in the LA group with spina bifida at 100 microg/mL and 1 mg/mL were similar to those observed in the adults in the LA group, suggesting that children are not at increased risk for systemic reactions compared with adults.

CONCLUSIONS

A suggestive clinical history is necessary but not sufficient for a definitive diagnosis of IgE-dependent latex allergy. These data support the safety and diagnostic efficacy of the Greer NAL, skin test reagent at 100 micro/mL and 1 mg/mL for confirmatory PSTs.

Factors affecting the retention of dust mite allergen on carpet

Carpeting is one of the most common and perhaps the most important reservoir of aeroallergens and other components of dust found in residential or commercial settings. This research evaluated factors that affect the retention of dust mite allergens on different types of tufted carpet commonly found in homes and offices. Twenty-six types of carpet were custom manufactured as part of a two-stage factorial experiment using 182 carpet samples. Carpets differed with respect to fiber denier, cross-sectional shape, presence of fluorocarbon treatment, carpet style, pile height, and pile density. The major hypothesis tested was that the amount of allergen-containing dust recovered from vacuum samples of tufted carpet sources was dependent on micro (fiber) or macro (construction) retention characteristics of the carpets. Carpet samples were doped in a uniform and reproducible manner using an allergen-containing reference dust. A standardized vacuum surface sampler was used to recover dust from samples. Allergen was assayed using a standard, monoclonal antibody ELISA. Carpet-surface area and presence of fluorocarbon were found to have the largest effects on retention and recovery of dust and allergen. Specifically, fluorocarbon treatment of fibers, square-hollow fiber shape, high-denier fiber, low-pile height in cut-pile carpets, and low-pile density in loop carpets were significantly associated with increased release and recovery of allergen. Results from this study suggest that carpet type be considered for both allergen avoidance and allergy and asthma risk assessment.

Prevalence of latex allergy among anesthesiologists: identification of sensitized but asymptomatic individuals

BACKGROUND

Occupational exposure to natural rubber latex has led to sensitization of health-care workers. However, the prevalence of latex allergy among occupationally exposed workers in American hospitals has not been reproducibly determined. The objectives of the current study were to determine the prevalence of and risk factors for latex sensitization among a cohort of highly exposed health-care workers.

METHODS

Participants were 168 of 171 eligible anesthesiologists and nurse anesthetists working in the Department of Anesthesiology and Critical Care Medicine. A clinical questionnaire was administered, and testing was performed using a characterized nonammoniated latex reagent for puncture skin testing, a Food and Drug Administration-approved assay to quantify latex-specific immunoglobulin E antibody in serum, and, when required for clarification, a validated two-stage (contact-inhalation) latex glove provocation procedure.

RESULTS

The prevalence of latex allergy with clinical symptoms and latex sensitization without clinical symptoms was 2.4% and 10.1%, respectively. The prevalence of irritant or contact dermatitis was 24%. The risk factors identified for latex sensitization were atopy (odds ratio, 14.1; 95% CI, 1.8-112.1; P = 0.012); history of allergy to selected fruits, such as bananas, avocados, or kiwis (odds ratio, 9.8; 95% CI, 1.6-61.9; P = 0.015); and history of skin symptoms with latex glove use (odds ratio, 4.6; 95% CI, 1.6-13.4; P = 0.006).

CONCLUSIONS

The prevalence of latex sensitization among anesthesiologists is high (12.5%). Of these, 10.1% had occult (asymptomatic) latex allergy. Hospital employees may be sensitized to latex even in the absence of perceived latex allergy symptoms. These data support the need to transform the health-care environment into a latex-safe one that minimizes latex exposure to patients and hospital staff.

Humanized antibodies as potential therapeutic drugs

BACKGROUND

Antibodies have been used therapeutically to treat a variety of clinical conditions. The introduction of monoclonal antibodies and more recently, engineered humanized antibodies has greatly refined and expanded the therapeutic potential of this modality of treatment.

LEARNING OBJECTIVES

To reinforce the reader's knowledge of the therapeutic application of antibody in the treatment for different diseases. More specifically, to enhance reader's understanding of basic methods employed in the production and clinical use of humanized antibodies.

DATA SOURCE

The MEDLINE database was used to review the humanized antibody related literature.

CONCLUSION

Humanized antibodies provide a novel approach for the treatment of a broad range of diseases. Expanded use will depend on improvement in their efficacy (avidity and specificity), demonstration of their safety, and reduction of their immunogenicity.

Repeated aerosol exposure to small doses of allergen. A model for chronic allergic asthma

To improve our understanding of the pathophysiology of chronic allergic asthma, we mimicked natural allergen exposure by giving tiny doses of dust-mite extract (equivalent to estimated daily exposure in a typical bedroom) in three weekly sessions for 4 wk. Nine mild asthmatic adults who were highly sensitive to dust-mite allergen participated in the study. Serial assessments of bronchial reactivity by methacholine challenge, pulmonary function, symptoms, and bronchodilator requirements were obtained. Seven of nine subjects had a twofold or more (median: 6, range: 2.7 to 25) reduction (p = 0.008) in PC20, after which saline inhalations were substituted for dust-mite extract. Bronchial reactivity returned to normal within 2 to 3 wk after cessation of dust-mite inhalations in all but one subject. Predosing FEV1 dropped 10% over 4 wk of provocation (p = 0.001) and 7 of 9 returned to prestudy level within 2 wk after dosing was stopped. Late-phase responses were seen in 6 of 9 subjects. We conclude that repeated aerosol exposure to dust-mite allergen in doses comparable to natural bedroom exposure is sufficient to adversely affect pulmonary function and bronchial hyperractivity in sensitized individuals. These changes are rapidly reversible. This low-dose provocational strategy provides an attractive model for the experimental study of allergic asthma. Arshad SH, Hamilton RG, Adkinson NF, Jr. Repeated aerosol exposure to small doses of allergen: a model for chronic allergic asthma.

Immunoglobulin E and eosinophil counts are increased after sepsis in trauma patients

OBJECTIVES

To determine the time course of plasma immunoglobulin E (IgE) concentration increases after traumatic injury, if increased IgE concentrations were related to clinical events or complications, and if increased peripheral eosinophil counts could be related to trauma, sepsis, or organ-specific complications.

DESIGN

Data relating to severity of injury, clinical complications, plasma concentrations of IgE, and peripheral eosinophil counts were prospectively collected.

SETTING

Trauma service, tertiary-care medical center.

PATIENTS

One hundred adult trauma patients admitted to the intensive care unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma IgE concentrations increased in most patients. However, the greatest increases were observed in patients with sepsis (p = .03), renal dysfunction (p = .04), or pneumonia (p = .02). IgE increases were not related to severity or mechanism of injury, allergy history, or age. The day of highest observed IgE concentration was related to the day of onset of sepsis (p = .012, r = .39), and occurred a mean of 3.8 days after sepsis. Most patients had increased peripheral eosinophil counts and eosinophil percentages of white blood cells during their intensive care unit stays. Eosinophil counts were greater in patients with sepsis (p < .0001), severe sepsis (p < .0001), or pneumonia (p < .002).

CONCLUSIONS

Increased IgE concentrations and eosinophil counts were found after sepsis and do not appear to be related to the initial injury. Since IgE and eosinophil production are enhanced by interleukin-4 and interleukin-5, respectively, these findings suggest that T-helper lymphocyte type 2 cytokines are activated in response to sepsis after traumatic injury.