Library

Notes: 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 chromalography. The isoelectric point of the antigen was about 9.7. The homogeneity of the antigen BG-60a was assessed by one single are of immunoprecipitation both in immanodiffusion 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.

Notes: Background The 33 kD component has been identified as a major allergen ofPenicillium citrinum, the most prevalent Penicillium species in the Taipei area of Taiwan.Objective This study analyses the isoforms, antigenic cross-reactivity and the N-terminal amino acid sequence of the 33 kD allergen of P. citrinum.Methods The composition of isoforms and antigenic cross-reactivity was analysed by SDS-PAGE and 2D-immunobIotting using MoAbs generated. The N-terminal sequence was analysed by using an automatic gas/liquid phase sequencer.Results Two MoAbs (55A and 34H) against the 33 kD allergen were generated in the present study. In addition to the 33 kD component. MoAb 34H also showed immunoblot reactivity to other components in the crude extract of P. citrinum. Analysed by 2D-immunoblotting. at least six different isoforms of the 33 kD component with pl values ranging from 6.75 to greater than 7.0 were shown to be reactive to both MoAbs and IgE antibodies in serum of an asthmatic patient. Different immunoblot patterns were observed when both MoAbs were reacted with four different strains of P. citrinum used in the present study. Among another six different Penicillium and four different Aspergillus species tested, only an immunoblot reactivity of MoAb 55 A to the 33 kD component of P. brevicompactum was observed. In 2D-immunoblotting. components of P. brevicompactum with an MW of about 33 kD and pi values similar to those of the 33 kD component of P. citrinum reacted with MoAb 55A and IgE antibodies in serum of the asthmatic patient. The N-terminal amino acid sequence of the 33 kD component of P. citrinum was determined to be ANVVQSNVP which was identical to the first 9 N-terminal amino acids of a heat-labile alkaline serine proteinase from P. citrinum.Conclusion Results obtained in the present study suggest that the 33 kD major allergen of P. citrinum may be an alkaline serine proteinase.

Notes: Background Penicillium citrinum has been identified as the most prevalent airborne Penicillium species in the Taipei area. However, detailed studies on allergens of this ubiquitous Penicillium species are still lacking.Objective For the characterization of allergens of this prevalent Penicillium species, molecular cloning and expression of the allergen genes of P. citrinum were performed in the present study.Methods Molecular cloning of the allergen genes was performed by using a λUni-Zap XR cDNA library of P. citrinum and serum from an asthmatic patient. The cloned cDNA was excised from the phage vector as a recombinant pBluescript phagemid and sequenced. The cDNA of the IgE-binding clone was expressed as fusion protein with the gultathione-S-transferase. The corresponding natural allergen was analysed by absorption immunoblotting using monoclonal antibody and serum from asthmatic patient. The frequency of IgE-binding to the allergen cloned was analysed by dot immunoassay using recombinant allergen and by immunoblotting using the whole extract of P. citrinum.Results In the screening of cDNA library of P. citrinum using serum from an asthmatic patient, IgE-binding cDNA clones designated SC4 and XL were obtained. The 5′-truncated, 0.7-kb and 1.7-kb cDNA inserts of clones SC4 and XL contained open reading frames of 163 and 503 amino acids, respectively. On alignment, the deduced amino acid sequences showed that 97 (60%) of the 163 amino acids and 376 (75%) of the 503 amino acids were identical to the corresponding amino acid sequence of the human heat shock protein in the hsp70 family. Both recombinant SC4 and XL showed positive SDS-PAGE-immunoblot reactivity to a monoclonal antibody MA3-006 against the human hsp 70 protein. For characterization of the corresponding natural allergen, immunoblotting reactivities of MA3–006 and IgE antibodies to the 70kDa component of P. citrinum have been shown to be disappeared after absorption of these antibodies with the recombinant SC4 protein. Sera from 14 (41%) of 34 Penicillium-allergic patients showed IgE-binding to the recombinant XL protein and the 70kDa component in the extract of P. citrinum.Conclusion Results obtained suggest that hsp 70 is an allergen of P. citrinum and that clones SC4 and XL contain partial cDNAs of this allergen gene.

Notes: Background Penicillium species have been considered as important causative agents of extrinsic bronchial asthma. However, little is known about the allergens of these ubiquitous airborne fungal species.Objective This study cotnpares the allergenic profiles and allergenic crossreactivity among allergens of three prevaletit airborne Penicillium species.Methods IgE-binding Penicillium components were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-immunoblotting using sera from 67 asthmatic patients. The presence of allergenic crossreactivity was analysed by immunoblot inhibition.Results Among the 67 serum samples tested, 15, 14 and 11 samples showed IgE reactivity to components of P. citrinun, P. notatum and P. brevicompactum, respectively. All 15 P. citrinum-positive serum samples showed IgE-binding to a 33 kDa extract component of this species. Thirteen (93%) of the 14 P. notatum-positive serum samples and 10 (91%) of the 11 P. brevicompactum-positive sera also showed IgE reactivity to components with a molecular weight of about 33 kDa in individual Penicillium species. All of the 10 P. brevicompactum 33 kDa component-positive serum samples showed IgE reactivity to the 33 kDa components of the other two Penicillium species tested. Dose-dependent inhibition of IgE-binding to these major allergens was observed when the positive serum sample was absorbed with different amounts of individual allergenic extract as well as with different amounts of extracts prepared from the other two Penicillium species.Conclusion Although different allergenie profiles were observed in the three different Penicillium species tested, results showed that there was an IgE crossreactivity among the 33 kDa group major allergens of P. citrinum, P. notatum and P. brevicompactum.

Notes: Background The recently characterized group 7 house dust mite allergens give positive skin-test reactions in 53% of allergie patients.Objective This study was performed to compare the IgE bindinig activity of natural and recombinant Der p 7, to measure the binding in allergic sera in comparison to major allergen Der p 2 and characterize the response by competitive inhibition with monoclonal antibodies.Methods IgE anti Der p 2 and Der p 7 antibodies against the recombinant allergens and monoclonal binding activities were measured by a solid phase radioimmune assay. Reslts A competitive binding assay showed that rDer p 7 inhibited 91% of IgE-binding to natural Der p 7 in 2 sera and 73% in a further two. The IgE binding of rDer p 2 and Der p 7 from 41 sera was then compared. Of the sera 88% and 46% respectively showed positive binding. All of the 19 sera which bound Der p 7 also bound Der p 2 but 11 (58%) had bound IgE to Der p 7 as high or higher than the binding to Der p 2. These sera were mostly high responders to both allergens. A panel of six monoclonal antibodies produced against either rDer p 7 or rDer f 7 was used for epitope analysis. All of these reaeted with eaeh allergen by enzyme linked immunosorbent assay (ELISA) and immunoblotting. Two patterns of cross inhibition of monoclonal antibody binding were observed and of five monoclonal antibodies tested, lour could inhibit the binding of IgE (WH9, WH22. WPS and HD19) while one (WH14) could not.Conclusions Although Der p 7 only reacts with 50% of allergic sera it often has a high IgE binding activity and may be more important than the major Der p 2 allergen in a high percentage of subjects. The combined competitive inhibition experiments show the IgE response is directed at several specilieities.

Notes: Aspergillus species are common airborne fungi that have been identified as causative agents of extrinsic bronchial asthma. More than 10 allergens from A. fumigatus have been recently characterized by cDNA cloning.The objective of this study is to identify A. fumigatus allergens through immunoblot analysis using sera from asthmatic patients.IgE-binding components of A. fumigatus and IgE cross-reactivity among allergens of different prevalent airborne fungal species were analysed by immunoblot and immunoblot inhibition, respectively, using sera from asthmatic patients. The N-terminal amino acid sequences of major allergens identified were determined by Edman degradation.Among two batches (70 and 41 sera) of asthmatic sera tested, 19 (27%) and 14 (34%), respectively, have IgE immunoblot reactivity towards components of A. fumigatus. A 34-kDa protein that reacts with IgE antibodies in 15 (79%) and 11 (79%) of the 19 and 14 positive samples, respectively, may be considered a major allergen of A. fumigatus. The N-terminal amino acid sequences of the 34 kDa major allergen and the 30.5 and 30 kDa IgE-binding components of A. fumigatus showed sequence identity to that of the vacuolar serine proteinase from A. fumigatus. The results from immunoblot inhibition show IgE cross-reactivity among major allergens of A. fumigatus, P. notatum and P. oxalicum.Results obtained suggest that the 34 kDa major allergen of A. fumigatus may be a vacuolar serine proteinase. There is IgE cross-reactivity among serine proteinase allergens of A. fumigatus, P. notatum and P. oxalicum.

Notes: Background The group 7 mite allergens react with IgE in 50% of sera from allergic patients.Objective To determine the molecular and antigenic characteristics and heterogeneity of Der f 7 in mite extracts.Methods Monoclonal antibodies (MoAbs) produced from mice immunized with recombinant Der f 7 were examined for crossreactivity to Der p 7 and then used for immunoblotting of 1 and 2-D gel electrophoresis. Deglycosylation was studied with N-glycosidase-F and N-terminal sequencing by Edman degradation. The epitopes of the monoclonal antibodies were compared by cross-inhibitory immunoassays.Results Immunoblotting of D. farinae extracts with all the anti Der f 7 MoAbs showed major reactivities at 31, 30 and 25 kDa. The strongest immunostaining was at 25 kDa which contrasted with Der p 7 where the 31 and 30 kDa bands were strongest. The relative strength of staining however varied between extracts. The 31 and 30 kDa components were glycosylation products of the 25 kDa form which had the N-terminal sequence predicted from cDNA analysis. Two MoAbs stained an 18 kDa band consistent with a degradation product. The 2-D gels showed that different components with pls from 5.6–6.4. Both species-specific and Der p 7 crossreactive MoAbs were produced and a two-site ELISA assay for detecting group 7 allergen was developed with MoAbs recognizing different epitopes.Conclusions Der f 7 has been defined by its natural N-terminal sequence and MoAbs. It apparently exists as different glycosylation and degradation products in mite extracts, the relative abundance of which differs with different preparations. A two-site ELISA to measure the allergen was developed.

Notes: A monoclonal antibody (MoAb P40) against the 68 kD major allergen of penicillium notatum (P. notatum) was obtained by immunizing the mouse with a crude extract of P. notatum. Analysed by two-dimensional gel electrophoresis and immunoblotting, P40 reacted with two different isoforms of the 68 kD component of P. notatum with pIs of 5.4 and 5.5. In addition to P. notatum, P40 showed positive ELISA activity to Aspergillus fumigatus (A. fumigatus) but not to components of six other fungi including Alternaria porri, Cladosporium cladosporoides, Aureobasidium pullulans, Fusarium solani, Rhizopus arrhizus and Candida albicans. Analysed by ELISA, MoAb P40 also showed positive activity to two (P. frequentans and P. roseopurpureum) of the 10 other Penicillium species and two (A. terreus and A. flavus) of the four other Aspergillus species tested. SDS-PAGE and immunoblotting studies demonstrated P40 positive reactivity to components with MW of about 67 kD in all these Penicillium and Aspergillus species with positive ELISA activity to P40. Furthermore, immunoblotting activity of MoAb P40 to the 67 kD component of A. niger was also observed. The epitope of the 68 kD allergen of P. notatum recognized by MoAb P40 was resistant to treatment of periodate oxidation with concentration of NaIO4 up to 20 mm. This MoAb may thus be useful in the characterization and purification of the 68 kD allergen from crude extracts, and in the molecular cloning of allergen genes.

Notes: Background Through proteomic and genomic approaches we have previously identified and characterized an alkaline serine protease that is a major allergen (88% frequency of IgE binding) of Penicillium chrysogenum (Pen ch 13).Objective The aim of the present study is to identify the linear IgE-binding epitopes of Pen ch 13.Methods IgE-binding regions were identified by dot-blot immunoassay using 11 phage-displayed peptide fragments spanning the whole molecule of Pen ch 13. The minimal epitope requirements for IgE binding were further defined with overlapping peptides synthesized on derivatized cellulose membranes using SPOTs technology. The critical residues on the immunodominant epitopes were mapped through site-directed mutagenesis. The locations of the IgE epitopes identified were correlated with a three-dimensional structure of Pen ch 13.Results IgE antibodies in 35 serum samples reacted with at least one of the 11 peptide fragments of Pen ch 13. Peptide f-2n (residues 31–61) showed a high-intensity and the highest frequency (77%) of IgE binding. The frequencies of IgE binding to peptide f-4 (residues 93–133), f-1 (residues 1–37) and f-7 (residues 168–206) were 51%, 34% and 31%, respectively. SPOTs assay narrowed down the region of IgE binding of f-2n to residues 48–55 (GHADFGGR). Three, two and one epitope(s) that are four to nine amino acids in length, within f-4, f-1 and f-7, respectively, were found. Site-directed mutagenesis of Pen ch 13 revealed that substitution of His49 and/or Phe52 on Pen ch 13 with methionine resulted in proteins with drastic loss of IgE binding in seven sera tested. Proteins with amino acid replacements at residues 15–18 (RISS), or at residues 112 (I) and 116 (D) have lower IgE-binding reactivity in one of the two patient's sera tested. Substituting residues 117 (W), 119 (V) and 120 (K) also block most of the IgE binding in one of the two patient's sera tested. In addition, replacing residues 203 (V) and 204 (D) along with a deletion at residue 206 (Y) diminished the IgE binding in two serum samples tested. A model was constructed based on the structure of P. cyclopium subtilisin protease that has 〉90% (256 out of 283 amino acids) sequence identity with Pen ch 13. The major epitope (GHADFGGR) on Pen ch 13 formed a loop-like structure and was located at the surface of the allergen.Conclusions Several linear IgE-reactive epitopes and their critical core amino acid residues were identified for the Pen ch 13 allergen. The major linear IgE-binding epitope, 48GHADFGGR55, formed a loop-like structure at the surface of the allergen. Substitution of His49 and/or Phe52 with methionine significantly reduced IgE-binding to Pen ch 13. Mapping of these results on a 3D model of the allergen provides valuable information about the molecular basis of allergenicity for Pen ch 13 and for designing specific immunotherapeutics.