Hans-Peter Rihs

IgE binding of the recombinant allergen soybean profilin (rGly m 3) is mediated by conformational epitopes

BACKGROUND Soybean proteins are constituents of a number of food products and represent a panel of potential allergens. Thus far, little is known about the molecular characteristics of soybean allergens. OBJECTIVE The aim of this study was to identify the soybean profilin by PCR-based complementary (c)DNA cloning and to elucidate its allergenic characteristics. METHODS Highly degenerate profilin-specific primers were used to identify, by means of PCR, 2 soybean profilin isoforms (GmPRO1 and GmPRO2) by using soybean cDNA as a target. One isoform (GmPRO1) with a length of 394 bp corresponding to 131 amino acid residues was subcloned and expressed in fusion with the maltose-binding protein. Moreover, 3 overlapping recombinant soybean profilin fragments comprising amino acid residues 1-65, 38-88, and 50-131 were also prepared as maltose-binding protein fusion proteins. IgE-binding reactivity of the recombinant proteins and the cross-reactivity of soybean profilin with birch profilin was studied by immunoblotting, enzyme-linked allergosorbent assays (EASTs), and competitive inhibition experiments by using serum samples from 13 soybean-sensitized subjects. RESULTS Results of immunoblot analysis, EAST, and EAST-inhibition experiments indicate the presence of profilin in soybean extract. The recombinant soybean profilin (rGly m 3) was recognized by IgE in 9 (69%) of the 13 sera tested. Only the full-length rGly m 3 was able to bind with IgE antibodies, whereas the 3 soybean profilin fragments did not show significant binding reactivity, indicating that the IgE binding to rGly m 3 depends on the integrity of a conformational structure, which was not present in the overlapping profilin fragments. The rGly m 3 cross-reacted with birch pollen profilin (Bet v 2), and the IgE binding to Bet v 2 could be inhibited by rGly m 3. CONCLUSIONS rGly m 3 represents a new soybean allergen with well-characterized primary sequence, and its IgE-binding reactivity is mediated by conformational epitopes.

On the allergenicity of Hev b 1 among health care workers and patients with spina bifida allergic to natural rubber latex

BACKGROUND Recent studies have caused much controversy about the prevalence of IgE antibodies to Hev b 1 among health care workers (HCWs) and patients with spina bifida (SB) who are allergic to latex. This investigation was carried out to verify the results reported. METHOD Serum samples from 140 patients with SB as well as from 105 HCWs allergic to latex were tested by enzyme allergosorbest test (EAST) and EAST-inhibition assay to evaluate the rate and degree of sensitization to highly purified Hev b 1. RESULTS Eighty-one percent of patients with SB who were allergic to latex had IgE antibodies against Hev b 1. The prevalence of anti-Hev b 1 antibodies among HCWs allergic to latex was 52.3%. In 15 of 33 serum samples from patients with SB that were randomly tested, the IgE binding to commercial latex allergens could be completely inhibited by Hev b 1; in only six cases was the maximum inhibition of IgE binding to latex by Hev b 1 less than 50%. Testing two monoclonal anti-Hev b 1 antibodies with extracts of five brands of latex gloves revealed a predominant presence of Hev b 1 protein as a monomer or its aggregates. Molecular analysis of human leukocyte antigen-D region genes DRB and DQB1 suggested no statistically significant correlation between the human leukocyte antigen alleles tested and IgE responsiveness to Hev b 1. CONCLUSIONS Our results indicate that Hev b 1 not only makes significant contributions to the IgE binding to latex, but it is also the unique sensitizer in about 45% of patients with SB who are allergic to latex.

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.

Multiple wheat flour allergens and cross-reactive carbohydrate determinants bind IgE in baker’s asthma

To cite this article: Sander I, Rozynek P, Rihs H‐P, van Kampen V, Chew FT, Lee WS, Kotschy‐Lang N, Merget R, Brüning T, Raulf‐Heimsoth M. Multiple wheat flour allergens and cross‐reactive carbohydrate determinants bind IgE in baker’s asthma. Allergy 2011; 66: 1208–1215.

IgE Reactivity to Profilin in Pollen-Sensitized Subjects with Adverse Reactions to Banana and Pineapple

Background: The so-called ‘latex-fruit syndrome’ is a well-documented phenomenon in cross-reactive allergies. By contrast, there is a lack of information about allergy to exotic fruits in patients with a predominant pollen sensitization. Since the ubiquitous protein profilin has been identified as an allergen in natural rubber latex as well as in pollen-related foods, the aim of this study was to investigate the role of profilin in allergy to certain exotic fruits. Methods: Recombinant profilins from banana and pineapple were cloned by a PCR technique after isolation of total RNA using degenerated profilin-specific primers. The unknown 5′ ends of copy DNA (cDNA) were identified by rapid amplification of 5′cDNA ends (5′-RACE) and expression in Escherichia coli BL21(DE3) cells. The recombinant profilins were purified by affinity chromatography using poly-(L)-proline as the solid phase. IgE-binding capabilities were characterized by means of immunoblot and Enzyme Allergosorbent Test (EAST). The cross-reactivity to birch pollen profilin and latex profilin was studied by EAST as well as by immunoblot inhibition experiments. Results: Both banana and pineapple profilin were found to consist of 131 amino acid residues with high amino acid sequence identity to known allergenic pollen and food profilins (71–84%). IgE binding to the recombinant profilins was observed in 7/16 sera from subjects with suspected banana allergy (44%) and in 8/19 sera from subjects with suspected pineapple allergy (42%). Inhibition experiments indicated similar IgE reactivity of natural and recombinant allergens. In addition, high cross-reactivity to birch pollen profilin Bet v 2 and latex profilin Hev b 8 was demonstrated by immunoblot inhibition as well as EAST inhibition experiments. Conclusions: Since a high IgE-binding prevalence of about 40% was obtained in both banana and pineapple allergy, we conclude that profilin is an important mediator of IgE cross-reactivity between pollen and exotic fruits.

Basophil Activation Test and specific IgE measurements using a panel of recombinant natural rubber latex allergens to determine the latex allergen sensitization profile in children.

There are no documented studies that describe natural rubber latex (NRL) sensitization in children with a history of surgical intervention but without any congenital malformation (urogenital anomalies, spina bifida, etc.), although some authors have studied NRL allergy in children without a history of surgical intervention. The aim of this work was to evaluate the sensitization profile to single NRL allergens in children without spina bifida and without repeated surgical interventions, by using different recombinant and natural latex allergens in two analytical techniques: specific serum immunoglobulin E (IgE) quantification and flow cytometry determination of activated basophils expressing CD63, after stimulating cells from patients with NRL allergens. A total of 23 patients and 10 healthy children were selected. Conjunctival and in‐use NRL provocation tests were carried out, as well as specific IgE determination in all patients’ and controls’ sera with the recombinant NRL allergens: rHev b 1, rHev b 2, rHev b 3, rHev b 5, rHev b 6.01, rHev b 6.02, rHev b 8, rHev b 9 and rHev b 11 and with NRL (k82) using appropriate ImmunoCAPs. The Basophil Activation Test (BAT) was performed with whole latex extract and with the recombinant allergens rHev b 5 and rHev b 6.01, as well as with the natural allergen Hev b 6.02. The sensitivity and the specificity of NRL‐specific IgE (k82) were 100%. Positive IgE responses to rHev b 5 were found in sera of 10 children, to rHev b 6.01 in 16 and for rHev b 6.02 in 15 childrens sera. Specific IgE to rHev b 8 was found in four sera of the children. We only found significant differences in sensitization to rHev b 5 in children with two or more surgical interventions compared with the non‐intervened group or those with only one intervention. Specific IgE in sera of children with latex‐fruit syndrome recognized rHev b 6.02, but not to rHev b 11. The patients sensitized to Hev b 8, Hev b 9 and/or Hev b 11 were atopic. The four patients presenting a positive response to the NRL profilin Hev b 8 were allergic to pollen. The BAT against whole NRL extract was positive in 22 of 23 children; against rHev b 5 in 14 of the patients studied; against rHev b 6.01 in seven cases and against nHev b 6.02 in 19 children. In all the control subjects, the results using this technique were negative. If combined rHev b 5, rHev b 6.01 and nHev b 6.02 together, BAT could detect 20 of the 23 children with latex allergy. The combined use of ImmunoCAP with all the recombinant NRL allergens and BAT with rHev b 5, rHev b 6.01 and nHev b 6.02, enabled the identification of NRL allergy in 22 of 23 patients. There is a positive and significant correlation between sensitization to Hev b 5 and the number of interventions. BAT and allergen‐specific IgE determination could be used as first‐line in vitro diagnostic tests in patients with NRL allergy.

No evidence for the influence of HLA class II in alleles in isocyanate‐induced asthma

Isocyanates are one of the main causes of occupational asthma. The aim of this investigation was to study the possible genetic background of isocyanate-induced asthma under consideration of the atopy status and different lung function parameters. We investigated the human leukocyte antigen (HLA) genes DRB1,3,4,5, DQB1, and DQA1 in 55 isocyanate-exposed patients with workplace-related dyspnea (32 asthmatics, 23 nonasthmatics) and 90 nonexposed controls. In contrast to other studies, we found no significant differences for any HLA class II allele tested in our study group. Furthermore, no significant differences concerning the aspartic amino acid residue 57 of DQB1 was observed. Therefore, we are unable to confirm an involvement of a specific HLA class II allele or DQB1-Asp57 in conferring susceptibility to isocyanate asthma in our study group.

Polymerase Chain Reaction Based cDNA Cloning of Wheat Profilin: A Potential Plant Allergen

Highly degenerate profilin-specific primers were used to amplify by polymerase chain reaction the profilin-coding sequence of wheat cDNA. Analyzing the sequencing data after subcloning revealed the existence of three isoforms. The high amino acid sequence identity with the birch pollen allergen Betv II suggests that wheat profilin may be a potential plant allergen, relevant in food allergy.

PCR-based cloning, isolation, and IgE-binding properties of recombinant latex profilin (rHev b 8).

Background: Profilin (Hev b 8) in natural rubber latex (NRL) has been assumed to be an important allergen. Since latex profilin has a molecular mass similar to two other latex allergens (Hev b 1 and Hev b 6.03) in the 14‐kDa range, it is difficult to obtain sufficient amounts of purified native profilin for investigations and diagnostics. The present study aimed to produce recombinant latex profilin (rHev b 8) and study its IgE‐binding reactivity.

Association of class II sequences encoding DR1 and DQ5 specificities with hypersensitivity to chironomid allergen Chi t I

A panel of 188 unrelated Caucasian subjects who were exposed to the larvae of Chironomus thummi (Diptera, nonbiting midges) was HLA-typed by polymerase chain reaction amplification of the second exons of the DRB, DQA1, and DQB1 genes followed by dot-blot hybridization with sequence-specific oligonucleotide probes. Type I sensitization to the allergen Chi t I and a large number of other inhalant allergens was determined by RAST and skin testing. Sixty-one individuals were found to be sensitized to Chi t I, of whom 24 were sensitive to this allergen and to no other allergens tested. Statistical analyses showed that only in the latter group were the HLA-D genes DRB1*0101, DQA1*0101, and DQB1*0501 associated with IgE-responsiveness to Chi t I. These results suggest that HLA associations with responsiveness to certain allergens may be more striking in monosensitized subjects.