In vitro cross-allergenicity of major aeroallergenic pollens by the radioallergosorbent technique

Assessing cross-reactivity in allergen immunotherapy

Knowledge of patterns of pollen cross-reactivity is crucial for formulation of immunotherapy vaccines. As phylogenetic relationships have become better clarified through the use of tools such as gene sequencing, it is apparent that cross-reactivity reflects taxonomy in the vast majority of cases. Contradictory observations of unexpected cross-reactivity between distantly related plants require explanation. There are many proteins, presumably performing vital functions, tightly preserved throughout the evolutionary tree from plants to animals. Examples are profilins, lipid transfer proteins, and pathogenesis-related proteins. These may function as panallergens. The small differences that exist between these ubiquitous proteins may explain why these are frequently minor allergens, not reacting in the majority of allergic sera. This article summarizes cross-reactivity from older studies using crude pollen extracts as well as newer research of purified or recombinant allergenic proteins. The patterns of cross-allergenicity that emerge should be helpful in guiding therapeutic decisions.

Allergy to oak pollen in North America

Background: Oak pollen is an important allergen in North America. The genus Quercus (oak) belongs to the family Fagaceae under the order Fagales. Objective: The objective of this article was to narratively review the oak pollen season, clinical and epidemiologic aspects of allergy to oak pollen, oak taxonomy, and oak allergen cross-reactivity, with a focus on the North American perspective. Methods: A PubMed literature review (no limits) was conducted. Publications related to oak pollen, oak-related allergic rhinitis with or without conjunctivitis, and oak-related allergic asthma were selected for review. Results: Oak species are common throughout the United States and contribute up to 50% to overall atmospheric pollen loads. Mean peak oak pollen counts can reach >2000 grains/m³. The start of the oak pollen season generally corresponds to the seasonal shift from winter to spring based on latitude and elevation, and may begin as early as mid February. The duration of the season can last > 100 days and, in general, is longer at lower latitudes. In the United States, ∼30% of individuals with allergy are sensitized to oak. The oak pollen season correlates with increased allergic rhinitis symptom-relieving medication use and asthma-related emergency department visits or hospitalizations. Oak falls within the birch homologous group. Extensive immunologic cross-reactivity has been demonstrated between oak pollen and birch pollen allergens, and, more specifically, their major allergens Que a 1 and Bet v 1. The cross-reactivity between oak and birch has implications for allergy immunotherapy (AIT) because guidelines suggest selecting one representative allergen within a homologous group for AIT, a principle that would apply to oak. Conclusion: Allergy to oak pollen is common in North America and has a substantial clinical impact. Oak pollen allergens are cross-reactive with birch pollen allergens, which may have implications for AIT.

Correlation of skin prick testing to environmental allergens

BACKGROUND

To diagnose and adequately treat allergies, identification of sensitizing allergens is crucial. Skin prick or serum immunoglobulin E testing determines sensitization to potential allergens. Consensus varies regarding degree of cross-reactivity between aeroallergens.

OBJECTIVE

To quantify correlations between aeroallergen skin prick test results.

METHODS

A total of 11,832 patients' quantitative skin prick test results and basic characteristics were obtained from a tertiary academic center's electronic medical record and deidentified. Data were analyzed using Spearman's rank correlation coefficients to detect nonlinear associations between wheal sizes of skin prick test results.

RESULTS

The highest correlation among grasses was 0.903 (fescue and red top). Of note, 13 more grass pairs had correlation more than 0.8, and 19 had correlation between 0.7 and 0.8. The Northern grass comparative results are from a satellite clinic that tested more grasses than the main clinic, in which only Kentucky blue and Bermuda were tested (correlation 0.768; n = 9348). Highest correlation among weeds was 0.74 (lambs quarter and pigweed). In addition, 6 more weed pairs had correlation more than 0.7. Highest correlation among trees was 0.724 (palm and alder) and 6 more tree pairs had correlation more than 0.7. Highest correlation among molds was 0.711 (Helminthosporium and Epicoccum). Dust mite correlation between Dermatophagoides farinae and Dermatophagoides pteronyssinus was 0.848 (n = 10,022).

CONCLUSION

This study confirmed the expected high degrees of correlation not only between skin prick test results of related environmental allergens but also between less closely related Northern grasses and Bermuda grass. This has implications for simplification of testing and immunotherapy protocols in the future.

Co-reactivity between related and unrelated environmental allergens in equine allergen-specific IgE serology testing in the UK

BACKGROUND

Identification of environmental allergens in horses with allergic disease facilitates allergen avoidance and targeted immunotherapy.

HYPOTHESIS/OBJECTIVES

To evaluate allergenic co-reactivity between 44 environmental allergens.

ANIMALS

Horses with suspected allergic disease (n = 344) whose sera were submitted for environmental allergen testing.

METHODS AND MATERIALS

Allergen-specific IgE serological assays were performed using 44 allergens divided into six taxonomically related groups: house dust/storage mites, moulds, insects, grass, tree and weed pollens. Using pairwise comparisons, odds ratios (ORs) were calculated for each environmental pair to determine if there was increased or decreased likelihood of a positive result for one allergen, given a positive result to another. The OR significance was set (using Holm-Bonferroni correction) at P < 0.00006 for all horses (n = 344) and P < 0.00005 for horses with at least one positive reaction (n = 239). Using one-way ANOVA with Tukey's post hoc tests (significance at P < 0.05), differences in mean log e ORs between three groups, taxonomically related allergens with a statistically significant association (related-associated), related allergens lacking a significant association (related-nonassociated) and unrelated allergens were tested.

RESULTS

Statistically significant associations were found between both related and unrelated allergen pairs, the former being more frequent. For all horses (n = 344) and horses with at least one positive reaction (n = 239), co-reactivity ranged from 100% (grasses) to 0% (moulds). The weeds group was exceptional in having more co-reactions with another group (grasses).

CONCLUSIONS AND CLINICAL IMPORTANCE

Co-reactivity was shown within and between certain related allergen groups. Further studies are required to determine whether this is the result of antigenic cross-reactivity.

Short ragweeds is highly cross-reactive with other ragweeds

BACKGROUND

The most widespread ragweed (Ambrosia) species in North America are short ragweed (Ambrosia artemisiifolia; Amb a), giant ragweed (Ambrosia trifida; Amb t), and western ragweed (Ambrosia psilostachya; Amb p). Varied geographic distributions of ragweed species raise questions regarding the need for ragweed species-specific allergen immunotherapy.

OBJECTIVE

To determine allergenic cross-reactivity among ragweed species by immunologic analyses of sera from subjects allergic to ragweed from North America and Europe.

METHODS

Sera were collected from 452 subjects allergic to ragweed who participated in Amb a sublingual immunotherapy tablet clinical trials. All subjects had positive skin prick test and serum IgE against Amb a. Ragweed-specific IgE (pre treatment) and IgG4 (post treatment) were measured by ImmunoCAP. IgE inhibition studies among Amb a, Amb t, and Amb p were conducted. Using pooled sera from another ragweed-allergic population, IgE inhibition studies of 7 less widespread Ambrosia species also were conducted.

RESULTS

A strong correlation between Amb a vs Amb p and Amb t serum IgE levels was observed. In the vast majority of pretreatment sera, Amb a inhibited Amb a, Amb p, and Amb t IgE reactivity by more than 90%. Strong correlations were observed between Amb a vs Amb p and Amb t post-treatment IgG4 levels. In pooled sera, Amb a extract inhibited the binding of serum IgE to all 10 ragweed species by 98%-100%.

CONCLUSION

In a population of subjects allergic to Amb a, substantial allergenic cross-reactivity among Amb a, Amb p, and Amb t was demonstrated. These in vitro data suggest that an Amb a-based single-species ragweed allergen immunotherapy may be therapeutically active in patients exposed to diverse ragweed pollens.

TRIAL REGISTRY

Clinicaltrials.gov, NCT00770315, NCT00783198, and NCT00330083.

Responsiveness to timothy grass pollen in individuals without known natural exposure in an allergen challenge chamber

BACKGROUND

The responsiveness to a nonendemic grass species is unknown and cannot be research without an allergen challenge chamber.

OBJECTIVE

To determine the clinical responsiveness to timothy grass pollen (TGP) in participants without known natural exposure in an allergen challenge chamber (ACC).

METHODS

Of the 26 screened participants, 22 met screening criteria and completed the 2 chamber exposures. The study consisted of an initial screening visit that included a blood draw for serum specific IgE (ssIGE) to Bermuda grass pollen and TGP followed by a 4½-day run-in phase and two 3-hour ACC exposure visits. This study was performed early in the first week of December 2013, when no seasonal pollens were detected in San Antonio, Texas. Symptom scores were recorded at baseline and every 30 minutes.

RESULTS

Of the 26 screened participants, 22 met the screening criteria and completed the 2 chamber exposures. Thirteen participants had always lived in South Texas without natural exposure, and 9 had previously lived in areas with TGP exposure. All participants tested positive to TGP and Bermuda grass pollen. Twelve and 13 of 22 had positive ssIgE test results to Timothy and Bermuda allergens, respectively, with 11 having positive results for both allergens. There were strong correlations among skin prick test size, a positive ssIgE test result, and high symptoms from TGP exposure. There was little difference in symptoms between those who had lived their entire lives in South Texas and those who had lived elsewhere.

CONCLUSION

In Texas, where exposure to TGP is minimal, strongly positive SPT and ssIgE test results were predictors of high symptoms to TGP exposure. Never exposed participants in South Texas reacted to TGP similar to those who had previous natural exposure, suggesting that in vivo cross-reactivity may be higher than predicted by prior in vitro data and may allow the use in clinical trials of allergens not endemic to the locale of an ACC.

Cross-reaction and co-sensitization among related and unrelated allergens in canine intradermal tests

BACKGROUND

Intradermal tests are used to identify allergens for avoidance and immunotherapy in atopic dogs.

HYPOTHESIS/OBJECTIVES

To evaluate cross-reaction or co-sensitization among 53 intradermal test allergens.

ANIMALS

Six hundred and fifty-one client-owned dogs with atopic dermatitis.

METHODS

Intradermal tests were performed with 53 house dust/storage mite, epidermal, insect, tree, weed and grass pollen and mould allergens. Pairwise comparisons were used to calculate the odds ratios (ORs), 95% confidence intervals (CIs) and statistical significance for the results of each allergen pair, with significance at P < 0.0006 (Holm-Bonferroni correction to reduce the false-detection rate).

RESULTS

Apart from cotton, cockroach, red clover, grain smut and Penicillium, the results for the allergens within each group were statistically associated [ORs from 4.7 (CI 2.5-8.9) to 1229.4 (CI 166.5-1795.1); P = 0.0005 to P < 0.0001]. Excluding red clover and cotton, 94% of results between tree, weed and grass pollens were also statistically associated [ORs from 8.3 (CI 3.6-24.7) to 117 (CI 29.1-341); P = 0.0005 to P < 0.0001]. In contrast, few allergens from unrelated groups were statistically associated [ORs from 0.12 (CI 0.03-1.1) to 27.7 (CI 0.2-93); P = 1.0 to P < 0.0001]. The mean (SD) of the log e transformed ORs for the related and statistically associated allergens [5.3 (1.3)] was significantly greater than those for related but nonstatistically associated [1.7 (1.6)] or unrelated allergens [1.4 (1.4); P < 0.0001].

CONCLUSIONS AND CLINICAL IMPORTANCE

This suggests that there is cross-reaction or co-sensitization between related allergens. This could have implications for allergen selection in testing and immunotherapy, but further studies are required to differentiate cross-reaction from co-sensitization.

Responses to ragweed pollen in a pollen challenge chamber versus seasonal exposure identify allergic rhinoconjunctivitis endotypes

BACKGROUND

The level of concordance between allergic symptoms induced on exposure to pollen in a pollen challenge chamber (PCC) versus the natural season is unknown.

OBJECTIVE

We sought to test the hypothesis that the symptom levels of allergic rhinoconjunctivitis elicited after out-of-season exposure to short ragweed in a PCC and during the natural season for giant ragweed pollen are highly correlated.

METHODS

Thirty-one ragweed-sensitive participants recorded symptoms for 15 days during the natural giant ragweed season in San Antonio, Texas. Twenty-six of these participants were challenged to short ragweed pollen in a PCC for 3 hours per day for up to 4 days.

RESULTS

In the PCC participants were dichotomized into those in whom low versus high levels of symptoms developed slowly or rapidly (ie, slow/low vs rapid/high). Each successive exposure visit associated with a progressive increase in symptom levels that approximated those experienced during the natural season. Hierarchic clustering identified 3 endotypes: endotypes I and II reflected concordantly low (n= 7) versus high (n = 14) total symptom scores (TSSs) in both the natural season and the PCC, respectively. Accordingly, the correlation between the TSSs recorded in the natural season and in the PCC for these 21 participants was very high. Although participants with endotype III (n = 5) had greater TSSs in the natural season than in the PCC, the degree of correlation between the TSSs remained high.

CONCLUSIONS

Our findings affirm our hypothesis, underscore the high cross-reactivity between distinct pollens, and highlight the utility of the PCC to identify novel allergy endotypes that might have contrasting mechanistic underpinnings and potentially therapeutic responses.

Giant ragweed specific immunotherapy is not effective in a proportion of patients sensitized to short ragweed: Analysis of the allergenic differences between short and giant ragweed

BACKGROUND

Short ragweed and giant ragweed pollen allergens are considered largely cross-reactive, and it is generally believed that 1 species is sufficient for skin testing and immunotherapy. However, in the area north of Milan (a zone widely invaded only by short ragweed), about 50% of patients submitted to injection specific immunotherapy with giant ragweed showed little or no clinical response, but showed an excellent outcome if they were shifted to short ragweed specific immunotherapy.

OBJECTIVE

To investigate allergenic differences between short and giant ragweed.

METHODS

IgE reactivity to short ragweed of sera from 16 patients allergic to ragweed was assessed by immunoblot before and after absorption with short and giant ragweed. Moreover, 41 ragweed-monosensitive patients underwent skin prick test with both ragweed species.

RESULTS

In several cases, preabsorption of sera with giant ragweed extract was unable to inhibit IgE reactivity fully against both a 43-kd allergen and other allergens at different molecular weights in short ragweed. On skin prick test, short ragweed induced larger wheals than giant ragweed in the majority of patients, and 6 of 41 (15%) patients were strongly short ragweed-positive but giant ragweed-negative. The immunoblot with the serum from 1 of these subjects showed a strong IgE reactivity to short ragweed at about 43 kd in the absence of any reactivity to giant ragweed.

CONCLUSION

Short and giant ragweed are not allergenically equivalent. Allergenic differences involve both the major allergens Amb a 1-2/Amb t 1-2 and some minor allergens. In patients allergic to ragweed, both diagnosis in vivo and immunotherapy should always be performed by using the ragweed species present in that specific geographic area.

Immunobiology of grass pollen allergens

Among pollen allergens, grass pollen allergens are some of the most frequent contributors to allergic symptoms. Substantial progress has been made since the 1960s in the identification and characterization of the grass allergens. Members of this group belong to the Poaceae family, and have been classified into 13 distinct groups based on their structure, and their biological and immunologic properties. The major contributors to allergy and, hence, most studied among the grass allergens, are those belonging to groups 1 and 5. This review is focused on the structure and immunobiology of the grass allergens and highlights how recent advances in the field have contributed to superior diagnosis and immunotherapy for allergy to grass pollens.

Lack of correlation between regional pollen counts and percutaneous reactivity to tree pollen extracts in patients with seasonal allergic rhinitis

BACKGROUND

Although seasonal patterns of tree pollination have been reported, it is unknown if aerobiologic data correlate with patterns of in vivo sensitization.

OBJECTIVE

To evaluate the relationship between regional tree pollen exposure and patterns of in vivo percutaneous reactivity to specific tree pollen extracts in a local patient population with seasonal allergic rhinitis.

METHODS

Patients with spring seasonal allergic rhinitis and percutaneous sensitivity to 1 or more regional tree pollens were studied. Tree pollen counts were collected at the same urban site from 1997 to 2002 and at a suburban site in 2002. Patients underwent skin prick testing with commercial extracts of 15 indigenous tree species. Serum specific IgE measurements were assayed in a subset of sensitized patients.

RESULTS

Of 127 patients who reported symptoms consistent with seasonal allergic rhinitis during the spring pollen season, 93 qualified based on demonstration of at least 1 positive skin prick test result. Mean 5-year pollen counts (1997-2001) and 2002 urban counts were highly correlated (Spearman r = 0.95, P < .001), indicating that year-to-year pollen counts were consistent. No significant correlation was found between mean seasonal pollen counts (urban site, 1997-2001) and frequencies of skin prick test reactivity to specific tree pollen allergens (Spearman r = -0.03, P = .93). No significant relationship was found between 5-year mean tree pollen counts and positive serum specific IgE tests for specific tree pollens (Spearman r = -0.42, P = .30). Eight of 15 species elicited percutaneous reactions in more than 50% of patients (ie, satisfying definition of a major in vivo allergen). However, 6 of the 8 major tree allergens each represented 5% or less of 5-year mean total tree pollen counts.

CONCLUSION

No correlation was found between overall frequencies of in vivo sensitization to tree pollen allergens in a local population and regional pollen exposure data.

Cross reactivity of airborne allergens based on 1000 intradermal test results

OBJECTIVE

The purpose of this study was to evaluate concurrent positive reactions of related versus nonrelated allergens based on 1000 intradermal tests of dogs with atopic dermatitis.

PROCEDURE

Pairs of closely related allergens (based on botanical relations and results of research in human allergic disease) and nonrelated allergens were evaluated. Significance of the difference between group means of log odds ratios was estimated using a Bootstrap percentile confidence interval.

RESULTS

There was a significant difference in the mean log odds ratio between related and nonrelated allergen pairs. However, there was also a significant difference between most groups consisting of nonrelated allergen pairs.

CONCLUSION

These results provide conflicting evidence and emphasise the need for further studies. Numbers of concurrent reactions of related allergens indicate that immunotherapy should be formulated based on testing with single allergens to avoid exposure to allergens not involved in the dog's atopic disease.

Cross-reactivity between coconut and hazelnut proteins in a patient with coconut anaphylaxis

BACKGROUND

The medical literature reports few cases of severe allergic reactions to coconut. We encountered a patient with anaphylaxis to coconut and oral symptoms to tree nuts.

OBJECTIVE

To identify cross-reactive antibodies between coconut and other tree nuts.

METHODS

We performed commercial radioallergosorbent tests to coconut and various tree nuts using the patient's serum. Skin prick testing was performed to fresh coconut and commercial extracts of coconut, almond, Brazil nut, cashew, pecan, walnut, and hazelnut. Proteins from fresh coconut, commercial coconut extract, and tree nuts were extracted. Immunoblot and inhibition assays were performed to evaluate for cross-reacting IgE antibodies between similar-sized allergens in coconut and hazelnut.

RESULTS

Positive skin test results occurred to the coconut and multiple tree nut extracts. In vitro serum specific IgE was present for coconut, hazelnut, Brazil nut, and cashew. Immunoblots demonstrated IgE binding to 35- and 50-kDa protein bands in the coconut and hazelnut extracts. Inhibition assays using coconut demonstrated complete inhibition of hazelnut specific IgE, but inhibition assays using hazelnut showed only partial inhibition of coconut specific IgE.

CONCLUSIONS

Our study demonstrates the presence of cross-reactive allergens between hazelnut (a tree nut) and coconut (a distantly related palm family member). Because there are many potentially cross-reactive allergens among the tree nuts, we recommend patients with coconut hypersensitivity be investigated for further tree nut allergies.

Key pollen allergens in North America

OBJECTIVE

To discuss major pollen aeroallergens in North America that are essential for effective immunotherapy and to propose a list of pollen aeroallergens that could be prioritized for allergen standardization.

DATA SOURCES

PubMed was used to search the existing medical literature. No date restrictions were used. Keywords included allergy, aeroallergen, taxonomy, cross-reactivity, pollen, and specific genus and species names.

RESULTS

Tree species possess relatively unique allergens, and representative members should be chosen at the genus or family level. In the Composite family, there is significant cross-reactivity between ragweed species within the Ambrosia genus. Selection of one species should be sufficient for skin testing and immunotherapy. Extensive allergenic cross-reactivity exists among grasses. Selection of timothy grass alone or in combination with a single northern grass species provides adequate coverage in the northeastern regions of North America.

CONCLUSIONS

One of the goals within the field of allergy should be to identify high-priority targets for future development of standardized commercial extracts. The standardization of increasing numbers of allergen extracts potentially benefits the discipline of allergy by facilitating transfer of care among physician practices, improving uniformity of patient care, and providing a template on which geographically specific extract choices can be built.

Patterns of pollen cross-allergenicity

Knowledge of patterns of pollen cross-reactivity is crucial for diagnostics and especially for formulation of immunotherapy vaccines in times of diminishing availability of pollen extract constituents. As phylogenetic relationships have become better clarified, it becomes apparent that cross-reactivity does reflect taxonomy in the very great majority of cases. Contradictory observations of unexpected cross-reactivity between unrelated plants, sometimes remarkably distant ones, require explanation. There are many proteins, presumably performing vital functions, that are tightly preserved throughout the evolutionary tree from plants to animals, such as profilins, lipid transfer proteins, and pathogenesis-related proteins. These might function as panallergens. The small differences that exist between these ubiquitous proteins explain why these are frequently minor allergens not reacting in the majority of allergic sera. This review summarizes cross-reactivity studies with both crude pollen extracts and purified or recombinant allergenic proteins. The patterns of cross-allergenicity that emerge should be helpful in guiding both diagnostic and therapeutic decisions.

Evaluation of cross-reactivity of allergens by use of intradermal testing in atopic dogs

OBJECTIVE

To examine cross-reactivity of aeroallergens in Colorado and surrounding states by evaluating concurrent positive reactions of related and nonrelated allergens of intradermal tests in dogs.

SAMPLE POPULATION

Intradermal test results of 268 atopic dogs.

PROCEDURE

A retrospective evaluation of skin test results for 268 dogs was performed. Pairs of closely related and nonrelated allergens were evaluated. Group 1 consisted of closely related allergens with demonstrated antibody cross-reactivity in humans. In group 2, allergens of the same plant group (ie, trees, grasses, or weeds) that were not closely related were paired. In group 3, allergen pairs were of different plant groups. Plant allergens were paired with dust mite allergens, animal dander, or mold spores in group 4. In the last group, allergens not derived from plants were paired. Data were evaluated twice by use of a different definition of a positive reaction. Significance of the difference between group means of log odds ratios was estimated by use of a boot-strap percentile confidence interval.

RESULTS

Significant differences in the number of concurrent positive reactions were not found between related versus nonrelated grass, weed, or tree allergens. Significant differences in the number of concurrent positive reactions were found between plant allergens of different groups (ie, grasses, weeds, and trees) and plant allergens of the same groups, related or nonrelated, as well as between plant-derived and nonplant-derived allergens. Many dogs reacting to a specific allergen did not react to a closely related allergen at the same time.

CONCLUSION

These results provide evidence against clinically relevant cross-reactivity and suggest that allergen-specific immunotherapy should be formulated on the basis of single allergen test results.

Occupational IgE-mediated asthma, rhinoconjunctivitis, and contact urticaria caused by Easter lily (Lilium longiflorum) and tulip

BACKGROUND

We report on IgE-mediated asthma, rhinoconjunctivitis, and contact urticaria to two Liliaceae plants, tulip and Easter lily (Lilium longiflorum), diagnosed in a floral shop worker.

METHODS

Occupational asthma was diagnosed according to patient history, PEF monitoring, and a work-simulating provocation test. Flower-specific IgE was studied, and RAST inhibition tests were performed.

RESULTS

Skin prick testing showed positive reactions to tulip, Easter lily, and chrysanthemum. Total IgE was 180 kU/I, and specific IgE to tulip was 2.6 and to Easter lily 6.5 kU/I. In the RAST-inhibition test, no cross-reactivity was found. Occupational asthma was diagnosed by peak flow monitoring at work and at home, as well as specific inhalation challenge with Easter lily, with an immediate 18% reduction in PEF. In addition, contact urticaria and conjunctivitis were diagnosed. After a 9-year follow-up without exposure to lilies, the skin prick tests to L. longiflorum and tulip were still positive, but the specific IgE had disappeared.

CONCLUSIONS

A case of IgE-mediated occupational asthma, rhinoconjunctivitis, and contact urticaria caused by L. longiflorum and tulip is presented. RAST inhibition tests indicated concomitant sensitization to the two Liliaceae plants.

Immunologic and physicochemical studies of Bermuda grass pollen antigen BG60

BACKGROUND

In a previous study we showed that antigen BG60 of Bermuda grass pollen contains isoallergens. Because the yield of purified isoallergens was low when a chromatofocusing technique was used, it was difficult to carry out further studies, such as determination of carbohydrate composition and structure.

OBJECTIVE

The aim of this study was to establish a procedure to purify antigen BG60 proteins as a group and to characterize this group's physicochemical and immunologic properties.

METHODS

A combination of chromatographic techniques (ion-exchange, gel filtration, blue gel affinity, and reverse-phase high-performance liquid chromatography) was used for the purification of BG60. Immunoblot and ELISA techniques were used to study BG60-specific IgE and IgG antibodies in patients' sera. The role of the carbohydrate moiety in antigenicity and allergenicity was examined with monoclonal antibodies and allergic sera by using periodate-treated BG60. Its carbohydrate composition was analyzed by high-performance anion-exchange chromatography with a pulsed amperometric detector.

RESULTS

Homogeneity of BG60 was demonstrated by a single sharp peak in reverse-phase high-performance liquid chromatography, a single band in sodium dodecylsulfate-polyacrylamide gel electrophoresis, and only one band stained by anti-BG60 monoclonal antibody. BG60-specific IgE and IgG antibodies were shown to be present in allergic sera. Six plant lectins were found to react with BG60. On periodate treatment, BG60 reduced binding toward its monoclonal antibody and human IgE and IgG. Carbohydrate composition analysis showed that BG60 contains three kinds of sugars: mannose, N-acetylglucosamine, and fucose (in a ratio of approximately 3:2:1) and a minute amount of xylose. The carbohydrate content is approximately 7.5%, and peptide content is about 92.5%.

CONCLUSION

A procedure was established for the purification of a large quantity of the BG60 antigen. The results suggest that the carbohydrate moiety of antigen BG60 may play an important role in the immune response.

Cloning and expression in yeast Pichia pastoris of a biologically active form of Cyn d 1, the major allergen of Bermuda grass pollen

BACKGROUND

Pollen of grasses, such as Bermuda grass (Cynodon dactylon), represent a major cause of type I allergy.

OBJECTIVE

In this report we attempted to clone and express a biologically active form of recombinant Cyn d 1, the major allergen of Bermuda grass pollen, in the yeast Pichia pastoris.

METHODS

Clones encoding Cyn d 1 were isolated by screening a Bermuda grass pollen complementary DNA library with specific monoclonal antibodies and by polymerase chain reaction amplification. Recombinant Cyn d 1 was expressed in Escherichia coli and yeast. The expressed proteins were analyzed by Western blotting to assess binding to Cyn d 1-specific monoclonal antibodies and IgE from sera of patients allergic to Bermuda grass pollen.

RESULTS

Two isoforms of Cyn d 1 were cloned. Recombinant Cyn d 1 expressed in bacteria bound two monoclonal antibodies raised against Cyn d 1 but was not recognized by IgE from sera of patients allergic to Bermuda grass pollen. Cyn d 1 expressed in yeast bound both the monoclonal antibodies and human IgE.

CONCLUSION

An IgE-reactive Cyn d 1 was expressed in yeast but not in bacteria, suggesting that posttranslational modifications (e.g., glycosylation), which occur in eukaryotic cells such as yeast, are necessary for the production of a biologically active allergen.

Recombinant expression and epitope mapping of grass pollen allergens

We have studied the expression of recombinant forms of Group 1 allergens from rye-grass and Bermuda grass pollens. Recombinant Lol p 1 expressed in bacteria bound serum IgE from allergic patients. Based on analysis of fragments of the Lol p 1 cDNA clone, the major IgE-reactive epitope has been mapped to the C-terminus. However, although SDS-denatured natural Cyn d 1 (from Bermuda grass) bound IgE, the full or partial recombinant proteins expressed in bacteria did not bind IgE. We have since expressed Cyn d 1 in the yeast Pichia pastoris and restored IgE binding. cDNA clones encoding two isoforms of Lol p 5, Lol p 5A and Lol p 5B, have been expressed in bacteria and resulting polypeptides show IgE-binding. Random fragments of these clones have been generated and when expressed as partial recombinant proteins in bacteria, allowed us to identify the major IgE-binding epitopes. The allergenic epitopes were localised towards the C-terminal half of the molecule. Although both isoforms shared similar IgE-reactive epitopes, Lol p 5B did not recognise the Lol p 5A-specific monoclonal antibody A7. At sequence level, there appear to be several amino acid differences between the antigenic epitopes of these two isoallergens. These results aid in the design of diagnostics and in grass pollen immunotherapy.

Detection of crossreactive determinants in grass pollen extracts using monoclonal antibodies against group IV and group V allergens

Monoclonal antibodies (MoAb) to defined allergens of P. pratense were raised. Five of them were selected for detailed studies by means of immunoblotting after SDS-PAGE and IEF of extracts from P. pratense and L. perenne. Three antibodies (1D11, 3B2, 2D1) recognize structures with mol. wt of 29 and 34 kD and pI of 4.8-7.6, corresponding to group V allergens. Two other MoAbs (2D8, 3C4) are directed against strong basic structures with a mol. wt of 50 kD and pI of 7.8-9.5 according to group IV allergens. The specificity of antibodies was supported by direct ELISA with purified group V and IV allergens. The isolated allergens were characterized before by SDS-PAGE and CIE and that allergenicity was detected with sera of patients with allergic rhinitis. Using our selected MoAbs crossreactive epitopes on group V and IV allergens have been excluded. Our antibodies have been used to detect crossreactivity in 14 grass pollen extracts. The evaluation of the pollen extracts has been performed by enzyme immunoassay (EIA) inhibition. One MoAb (3C4) is able to recognize group IV allergens in all grass species analysed whereas the MoAb 2D8 seems to identify group IV structures in selected grasses only. Binding to conserved structures of group V has been proved for MoAb 1D11. Other group V specific MoAbs (2D1, 3B2) identify similar, however incomplete, spectra. These results have been confirmed also by the dot immunobinding assay.

Group V allergens in grass pollens: IV. Similarities in amino acid compositions and NH2-terminal sequences of the group V allergens from Lolium perenne, Poa pratensis and Dactylis glomerata

Monoclonal antibodies (PpV4) raised against Phleum pratense group V allergen were used for immuno-affinity chromatography of cross-reacting group V allergens from related grass species. Fractions enriched in group V allergen were obtained from Lolium perenne, Poa pratense and Dactylis glomerata extracts. The major components in these fractions were found in the Mwr range 25-28 kD. IgE binding to these components was shown using a pool of grass allergic sera, by SDS-PAGE immunoblotting. These fractions were electroblotted from tricine SDS-PAGE gels onto a polyvinylidene-difluoride membrane and selected group V bands were directly cut out and used for amino acid analysis and NH2-terminal sequencing. Both the amino acid compositions and the NH2-terminal sequences obtained for each group V allergen were almost similar to each other and to the sequence and composition of the previously described allergen Phl p V from Phleum pratense. A common trait of the investigated allergens, is the very high contents of alanine (25-32%) and the presence of the modified amino acid, hydroxyproline.

Characterization of the major allergen of Cynodon dactylon (Bermuda grass) pollen, Cyn d I

An allergen from Cynodon dactylon (Bermuda grass) pollen, Cyn d I, has been purified by a combination of concanavalin A-Sepharose affinity chromatography, and carboxymethyl-Sepharose chromatography. The allergen constitutes the major allergenic component of the pollen extract as observed by immunoelectrophoretic techniques, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, an IgE-inhibition experiment, and skin testing. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Cyn d I is presented as a dominant 32 kd band and a minor 29 kd band, both binding IgE. Both bands are identified by monospecific rabbit antibodies (Abs) raised against Cyn d I. These Abs only weakly precipitate allergens from other grass species, indicating that Cyn d I possesses some unique immunochemical properties. Two of four purified murine monoclonal Abs raised against Cyn d I also bind to both bands of Cyn d I, indicating that the bands represent isoallergens with slightly different immunochemical properties. All four monoclonal Abs cross-react with pollen components from other grass species, especially Poa pratensis and Dactylis glomerata. The NH2-terminal sequence corresponding to approximately 10% of the complete sequence was determined, and it revealed high homology to the corresponding sequence of the major allergen of Lolium perenne, Lol p I. From the amino acid composition determination and immunoelectrophoretic comparison, the amount of Cyn d I in the source whole-pollen extract was estimated to be 15% wt/wt.

Isolation and partial characterization of Bermuda grass pollen allergen, BG-60a

In an earlier study we showed that Bermuda grass (Cynodon dactylon) pollen contains at least 12 IgE-binding proteins that can be analysed by immunoblot technique. One of the active components (BG-60) proved to be a basic protein of glycoprotein nature. It contained about 28% carbohydrate as determined from the dry weight and consisted of four molecules. One of the components was purified from the pollen extract by a combination of ammonium sulphate precipitation, ion-exchange chromatography on carboxymethyl-TSK, gel filtration on Ultrogel AcA 44 and chromatofocusing. Its molecular weight was approximately 60 kD by SDS-PAGE and 34 kD by gel filtration chromatography. The isoelectric point of the antigen was about 9.7. The homogeneity of the antigen BG-60a was assessed by one single arc of immunoprecipitation both in immunodiffusion and crossed immunoelectrophoresis and by one single band after SDS-PAGE. Its allergenicity was demonstrated by direct intradermal skin test on allergic patients and by examining IgE-binding reactivity with allergic patients' serum.

Group V allergens in grass pollens. II. Investigation of group V allergens in pollens from 10 grasses

In an earlier study an allergen from Phleum pratense (timothy) pollen, Phl p V, has been isolated and physicochemically characterized. In this study Phl p V and immunochemically similar components from other grass pollens (group V allergens) have been investigated using immunoelectrophoretic techniques. To study the allergenic importance of the group V allergens, the allergenic compositions of 10 grass pollen extracts were investigated in crossed radioimmunoelectrophoresis (CRIE) using 20 sera from grass pollen-allergic donors. Group V allergens were identified using monospecific rabbit antibodies raised against Phl p V, anti-Phl p V, which react with other group V allergens usually producing dense precipitates in immunoelectrophoresis. In this way group V allergens were identified in eight extracts, and when present the precipitate corresponding to the group V allergen was the dominant IgE binding precipitate. All identified group V allergens bound IgE in at least 17 of the 20 investigated sera. Monospecific rabbit antibodies raised against the group I allergen of Lolium perenne (rye grass), anti-Lol p I, do not precipitate group V allergens, indicating that there are no immunochemical similarities between group I and group V allergens. In SDS-PAGE anti-Phl p V identifies IgE-binding components with molecular weights between 26 and 33 kD. In contrast, anti-Lol p I binds to components of slightly higher molecular weight. Apparently, the group V components are allergens that are physicochemically and immunochemically distinct from group I allergens.

Cold air challenge and platinum skin reactivity in platinum refinery workers. Bronchial reactivity precedes skin prick response

An investigation of a platinum refinery operation consisted of an administered questionnaire, spirometry, skin prick testing with platinum salts and common aeroallergens, serum total IgE, radioallergosorbent test for platinum salts, and measurement of nonspecific airway hyperresponsiveness by cold air challenge testing. Among 136 employees examined, there were 107 current and 29 medically terminated workers; 23 (17 percent) subjects had a positive platinum salts prick skin test and 19 (14 percent) displayed a positive cold air challenge. RAST binding for platinum salts IgE antibodies showed a high level of agreement with platinum skin prick test results. A proportion (63 percent) of the population (74 current and 12 terminated workers) underwent repeat platinum skin testing one year later. Among current workers, there was conversion of the platinum skin test from negative to a positive test in five employees, with three conversions occurring in workers who showed only a positive cold air challenge test the year before. Platinum skin sensitivity, asthma symptoms, and nonspecific airway hyperresponsiveness persisted for years after termination of exposure in some medically terminated workers presumably because of a delay in removal from work of employees who became sensitized to platinum salts. It is suggested that proper surveillance for occupational asthma involves the use of several testing procedures. Prompt removal from work of individuals found to become sensitized to platinum salts is important in this industry.

Antibodies to morphine in workers exposed to opiates at a narcotics manufacturing facility and evidence for similar antibodies in heroin abusers

According to the International Narcotics Control Board, over 45,000 kg of morphine and 54,000 kg of codeine were ethically manufactured in 1986 at three facilities in the United States. Little information exists about possible adverse health effects associated with workplace exposure to opiate compounds in this industry. Because there are no specific federal standards for workplace exposure to narcotic dusts, exposure-control defaults to the nuisance dust standard (10 mg/m3, as an 8 hr time-weighted average). Narcotics manufacturing workers were evaluated for anti-morphine IgG before and 10 mo. after the implementation of an improved respiratory protection program (RPP). Significantly elevated IgG levels were measured before the improved RPP (P less than 0.005). After the improved RPP, a significant reduction was observed (P less than 0.001), suggesting that specific antibody levels could be used as biomarkers of exposure. Inhibition studies showed that the antibodies were specifically directed against morphine with some cross reactivity with morphine derivatives. Preliminary results are also shown which indicate that similar anti-morphine antibodies are present in the sera of intravenous heroin abusers. Elevated levels (P less than 0.05) of anti-morphine antibodies were detected in sera from heroin abusers, providing evidence that similar antibodies may be produced from non-occupational exposure to opiates. These finding have potentially far-reaching implications for addiction research and drug testing.

An immunoelectrophoretic analysis of the allergens of Cynodon dactylon (Bermuda grass) pollen

A crude extract of Cynodon dactylon (Bermuda grass) pollen was obtained by extraction, centrifugation, dialysis, and lyophilization. The corresponding polyspecific rabbit antibodies were obtained by immunization, bleeding, and purification and were used for a cross immunoelectrophoretic analysis of the crude extract. At least 52 antigens (Ags), of which 47 migrated toward the anode, and five, toward the cathode, were revealed. Crossed radioimmunoelectrophoretic analysis performed with sera from 32 patients allergic to Bermuda grass and a pool from 1000 normal individuals revealed specific IgE binding to 13 of these Ags. The approximate molecular weights (MWs) for 10 of these IgE-binding Ags were determined by a combination of gel filtration and immunochemical analysis. These Ags had apparent MWs greater than 14 kd. A combination of preparative sucrose gradient isoelectric focusing and immunochemical analysis was used to determine the approximate isoelectric point values of five of the IgE-binding Ags. Most precipitating Ags had isoelectric points between 4.5 and 5.5. Four of the Ags (Ag 24, MW, less than 65 kd; Ag 31, MW, 33 kd; Ag 33, MW, 20 kd; and Ag 34/35, MW, 32 kd) were classified as major allergens.

Immune responses of cynomolgus monkeys to phthalic anhydride

Four groups of four Macaca fascicularis monkeys were administered 10 consecutive weekly subcutaneous injections of 2 mg aluminum hydroxide plus one of the following: 200 micrograms of phthalic anhydride (PA)-monkey serum albumin (PA-MSA, group 1); 200 micrograms of PA dissolved in ethanol-saline (EtOH-sal, group 2); 200 micrograms of MSA (group 3); or EtOH-sal alone (group 4). Direct intracutaneous tests to PA-MSA, PA-EtOH-sal, MSA, and EtOH-sal were applied at biweekly intervals throughout the course of the immunization. Serum-specific IgG to PA-MSA and specific IgE to PA-MSA were determined at 2-week intervals according to the ELISA and RAST methods, respectively. The prevalence of cutaneous sensitivity to PA-MSA in the PA-MSA-immunized group (group 1) was significantly greater after 4 and 6 (p less than 0.01) and 8 and 10 (p less than 0.05) weeks, compared with the other treatment groups. Significantly elevated (p less than 0.01) PA-MSA-specific IgG was also observed in monkeys in group 1 compared with the other treatment groups. No significant changes in PA-MSA RAST or total IgE were observed in any group during the study. These results indicate that parenteral sensitization to PA in subhuman primates requires the presence of new antigenic determinants formed by PA on protein carriers.

Pulmonary and immunologic evaluation of foundry workers exposed to methylene diphenyldiisocyanate (MDI)

A cross-sectional evaluation was performed of workers in a steel foundry in which methylene diphenyldiisocyanate (MDI) was used as a component of a binder system used to make cores and molds. Preshift and postshift spirometry and clinical evaluations were performed on 26 currently exposed (group I), on six formerly exposed (group II), and on 14 nonexposed workers to MDI (group III). Serum samples were assayed for total antibody binding, specific IgG by ELISA, and specific IgE by the RAST method to MDI-human serum albumin (HSA). Symptoms compatible with occupational asthma were elicited from seven (27%) of 26 group I workers and from three of six group II workers. No symptoms were reported by group III workers. Intrashift change in FEV1 (a mean decrease of 0.049 L) in group I workers was significantly decreased compared to that in unexposed group III workers (a mean increase of 65 ml; p = 0.043). Specific IgG and total antibody responses to MDI-HSA were detected only in workers with current or former exposure to MDI. Only one worker was identified with IgE-mediated occupational asthma exhibiting a positive prick test and elevated RAST to MDI-HSA of 25.5% bound. In this occupational setting, polyclonal immune responses to MDI-HSA and clinical sensitization to MDI were demonstrated to occur.

Allergenicity and cross-reactivity of rye grass pollen extracts revealed by monoclonal antibodies

Using monoclonal antibodies the immunogenic and allergenic characteristics of rye Group I were redefined by SDS-PAGE analysis and immunoblotting. The purified rye Group I from NIH possesses a major component of approximately 34000 Da against which most of the sera from grass-sensitive patients and none from non-atopic volunteers contain specific IgE antibodies. Monoclonal antibodies to rye Group I were raised and used to purify the antigen and to verify the cross-reactivity between grass extracts. The 3 monoclonal antibodies studied recognized different components of timothy grass and 2 of them recognized kentucky june grass but none recognized components of ragweed extracts.

Allergy in the Mediterranean area. II: Cross-allergenicity among Urticaceae pollens (Parietaria and Urtica)

Pollens of related species usually share common antigens and are cross-reacting but this is not always the case. The cross-allergenicity of two species of Urticaceae pollens (Parietaria and Urtica, nettle) was sought by means of RAST-inhibition and isoelectric focusing. A preliminary experiment in forty-two patients investigated by means of skin tests and RAST showed that most patients were either allergic to Parietaria or nettle and that both reactivities were uncommonly associated. The results of RAST-inhibition confirmed the total absence of cross-reactivity between these two related species. IEF patterns indicated that most proteins are in the acidic range of pH and did not reveal large discrepancies. Parietaria and Urtica pollens, although belonging to the same family and having close microscopic patterns, have very different allergenic activities. This study demonstrates that cross-allergenicity cannot be predicted.