An update on Ym1 and its immunoregulatory role in diseases.

Ym1 is a rodent-specific chitinase-like protein (CLP) lacking catalytic activity, whose cellular origins are mainly macrophages, neutrophils and other cells. Although the detailed function of Ym1 remains poorly understood, Ym1 has been generally recognized as a fundamental feature of alternative activation of macrophages in mice and hence one of the prevalent detecting targets in macrophage phenotype distinguishment. Studies have pointed out that Ym1 may have regulatory effects, which are multifaceted and even contradictory, far more than just a mere marker. Allergic lung inflammation, parasite infection, autoimmune diseases, and central nervous system diseases have been found associations with Ym1 to varying degrees. Thus, insights into Ym1's role in diseases would help us understand the pathogenesis of different diseases and clarify the genuine roles of CLPs in mammals. This review summarizes the information on Ym1 from the gene to its expression and regulation and focuses on the association between Ym1 and diseases.

Comparative analysis of the allergenic characteristics and serodiagnostic potential of recombinant chitinase-like protein-5 and -12 from Sarcoptes scabiei.

BACKGROUND: Scabies is caused by burrowing of the mite Sarcoptes scabiei into the stratum corneum. Currently, diagnosis via routine skin scraping is very difficult, and information on the allergenic identification of S. scabiei remains limited. METHODS: We performed comparative analysis of the serological diagnostic potential of recombinant S. scabiei chitinase-like protein-5 (rSsCLP5) and recombinant S. scabiei chitinase-like protein-12 (rSsCLP12) by measuring the levels of serum-specific IgG and IgE antibodies (Abs) as diagnostic markers. In addition, the allergenic characteristics of rSsCLP5 and rSsCLP12 were evaluated using IgE-binding experiments and skin tests. RESULTS: The IgE Abs-based indirect enzyme-linked immunosorbent assay (ELISA) methods showed high sensitivity and specificity: the rSsCLP5-based assay had 93.5% sensitivity and 94.4% specificity; the rSsCLP12-based assay had 100% sensitivity and 98.1% specificity. The specific IgE Abs in infested mouse sera could bind rSsCLP5 and rSsCLP12. In skin tests, rabbits in the rSsCLP5 and rSsCLP12 groups and positive control (histamine) groups exhibited allergic reactions. Most test sites in the rSsCLP12 group had edema, bleeding spots, and even ulcers or scabs, but such allergy symptoms were rare in the rSsCLP5 group. Moreover, the allergic history rabbit group had more severe allergic reactions and lower levels of IgE Abs compared to the healthy rabbit group in the same protein group. CONCLUSIONS: These findings validate the use of IgE Abs to rSsCLP5 and rSsCLP12 as potentially useful markers for diagnosing scabies. Moreover, both rSsCLP5 and rSsCLP12 have allergenic properties, and the potential allergen rSsCLP12 is a stronger allergen than rSsCLP5.

Altered Macrophage Function Associated with Crystalline Lung Inflammation in Acid Sphingomyelinase Deficiency.

Deficiency of ASM (acid sphingomyelinase) causes the lysosomal storage Niemann-Pick disease (NPD). Patients with NPD type B may develop progressive interstitial lung disease with frequent respiratory infections. Although several investigations using the ASM-deficient (ASMKO) mouse NPD model revealed inflammation and foamy macrophages, there is little insight into the pathogenesis of NPD-associated lung disease. Using ASMKO mice, we report that ASM deficiency is associated with a complex inflammatory phenotype characterized by marked accumulation of monocyte-derived CD11b+ macrophages and expansion of airspace/alveolar CD11c+ CD11b- macrophages, both with increased size, granularity, and foaminess. Both the alternative and classical pathways were activated, with decreased in situ phagocytosis of opsonized (Fc-coated) targets, preserved clearance of apoptotic cells (efferocytosis), secretion of Th2 cytokines, increased CD11c+/CD11b+ cells, and more than a twofold increase in lung and plasma proinflammatory cytokines. Macrophages, neutrophils, eosinophils, and noninflammatory lung cells of ASMKO lungs also exhibited marked accumulation of chitinase-like protein Ym1/2, which formed large eosinophilic polygonal Charcot-Leyden-like crystals. In addition to providing insight into novel features of lung inflammation that may be associated with NPD, our report provides a novel connection between ASM and the development of crystal-associated lung inflammation with alterations in macrophage biology.

Chitinase involved in immune regulation by mediated the toll pathway of crustacea Procambarus clarkii.

Chitinase can degrade chitin and play an essential role in animal immunity and plant defense. The immune functions of Chitinase in Procambarus clarkii (P. clarkii) remain to elucidate. Here, we identified PcChitinase 2 gene sequence from P. clarkii and studied its spatial and temporal expression profiles. The PcChitinase 2 transcribed unequally in different tissues; however, its expression was highest in those of stomach, gut, and hepatopancreas. The challenge with lipolysaccharide or peptidoglycan significantly up-regulated the expression of PcChitinase 2 in hepatopancreas. The knockdown of the PcChitinase 2 gene by double-stranded RNA suppressed most of the Toll-pathway-related immune genes (phospholipase, lectin, sptazle Cactus, serine proteikinase, anti-lipopolysaccharide factor, and Toll) production were significantly increased. Our results suggest PcChitinase 2 may be involved in the innate immune responses of P. clarkii by modulating the toll pathway.

A double chitin catalytic domain-containing chitinase targeted by c-Jun is involved in immune responses in shrimp.

Chitinases are a group of chitin-degrading enzymes widely distributed in organisms. Chitinases containing two chitin catalytic domains have been widely found in arthropods but their functions remain unclear. In this study, a member of these chitinases from Litopenaeus vannamei (dChi) was identified and functionally studied in the context of immunity. The promoter of dChi contained activator protein 1 (AP-1) binding sites and could be regulated by c-Jun. The recombinant dChi protein showed no bacteriostatic activity in vitro but knockdown of dChi in vivo increased the mortality of shrimp and the bacterial load in tissues after Vibrio parahaemolyticus infection, suggesting that dChi could play a positive role in antibacterial responses. However, silencing of dChi expression significantly decreased the mortality of WSSV-infected shrimp and down-regulated the viral load in tissues, indicating that dChi could facilitate WSSV infection. We further demonstrated that dChi was involved in regulation of the bacterial phagocytosis of hemocytes and expression of a series of immune related transcription factors and antimicrobial peptides. These indicated that the roles of dChi in antibacterial responses and anti-WSSV responses in vivo could result from its regulatory effects on the immune system. Taken together, the current study suggests that double chitin catalytic domain-containing chitinases could be important players in immune regulation in crustaceans.

Characterization of a Novel Chitinase from Sweet Potato and Its Fungicidal Effect against Ceratocystis fimbriata.

Black rot, caused by Ceratocystis fimbriata, is a destructive disease of sweet potatoes (Ipomoea batatas). In this study, a novel chitinase (IbChiA) was screened from sweet potatoes, which showed a remarkably higher expression level in resistant varieties than in susceptible ones after inoculation with C. fimbriata. Sequence analysis indicated that IbChiA belongs to family 19 class II extracellular chitinase with a MW of 26.3 kDa and pI of 5.96. Recombinant IbChiA, produced by Pichia pastoris, displayed antifungal activity and stability. IbChiA could restrain the mycelium extension of C. fimbriata. FDA/PI double staining combined with transmission electron microscopy observation revealed the remarkable fungicidal effect of IbChiA on the conidia of C. fimbriata. The disease symptoms on the surface of slices and tuberous roots of sweet potatoes were significantly reduced after treatment with IbChiA. These results indicated that IbChiA could be used as a potential biofungicide to replace chemical fungicides.

Interactions between macrophages and helminths.

Macrophages, the major population of tissue-resident mononuclear phagocytes, contribute significantly to the immune response during helminth infection. Alternatively activated macrophages (AAM) are induced early in the anti-helminth response following tissue insult and parasite recognition, amplifying the early type 2 immune cascade initiated by epithelial cells and ILC2s, and subsequently driving parasite expulsion. AAM also contribute to functional alterations in tissues infiltrated with helminth larvae, mediating both tissue repair and inflammation. Their activation is amplified and occurs more rapidly following reinfection, where they can play a dual role in trapping tissue migratory larvae and preventing or resolving the associated inflammation and damage. In this review, we will address both the known and emerging roles of tissue macrophages during helminth infection, in addition to considering both outstanding research questions and new therapeutic strategies.

Sodium alginate potentiates antioxidant defense and PR proteins against early blight disease caused by Alternaria solani in Solanum lycopersicum Linn.

The use of biopolymers as elicitors in controlling plant diseases is gaining momentum world-wide due to their eco-friendly and non-toxic nature. In the present study, we have used an algal biopolymer (sodium alginate) and tested its applicability as an elicitor in inducing resistance factors against Alternaria solani, which causes early blight disease in Solanum lycopersicum (tomato plant). We have pre-treated tomato plants with different concentrations of sodium alginate (0.2%, 0.4%, and 0.6%) before A. solani infection. We found that sodium alginate has effectively controlled the growth of A. solani. In addition, a significant increase in the expression levels of SOD was observed in response to pathogen infection. The increased protease inhibitors activity further suggest that sodium alginate restrict the development of A. solani infection symptoms in tomato leaves. This corroborates well with the cell death analysis wherein increased sodium alginate pre-treatment results in decreased cell death. Also, the expression profile analyses reveal the induction of genes only in sodium alginate-pretreated tomato leaves, which are implicated in plant defense mechanism. Taken together, our results suggest that sodium alginate can be used as an elicitor to induce resistance against A. solani in tomato plants.

Chitinases as Food Allergens.

Food allergies originate from adverse immune reactions to some food components. Ingestion of food allergens can cause effects of varying severity, from mild itching to severe anaphylaxis reactions. Currently there are no clues to predict the allergenic potency of a molecule, nor are cures for food allergies available. Cutting-edge research on allergens is aimed at increasing information on their diffusion and understanding structure-allergenicity relationships. In this context, purified recombinant allergens are valuable tools for advances in the diagnostic and immunotherapeutic fields. Chitinases are a group of allergens often found in plant fruits, but also identified in edible insects. They are classified into different families and classes for which structural analyses and identification of epitopes have been only partially carried out. Moreover, also their presence in common allergen databases is not complete. In this review we provide a summary of the identified food allergenic chitinases, their main structural characteristics, and a clear division in the different classes.

Development and Characterization of a Novel Monoclonal Antibody Against Chitinase-like Protein CHID1 Applicable for Immunohistochemistry on Formalin Fixed Paraffin-Embedded Sections.

CHID1 has been recently described as a predictive marker of different malignant tumors. Thus, monoclonal antibodies (mAbs) for CHID1 detection in different human liquids and in tissues are an important tool for the diagnosis of CHID1-positive cancers. However, only few mAbs have been established to date. In this study we describe the generation of a new hybridoma clone 3D4 producing anti-CHID1 antibodies. 3D4 mAb specifically binds human CHID1 and was successfully used in enzyme-linked immunosorbent assay, immunoblotting, immunofluorescence on paraformaldehyde-fixed cells, and in immunohistochemistry of paraffin-embedded tissue specimens. These results indicate that this new anti-CHID1 mAb 3D4 will be useful in the diagnosis of CHID1-related cancers and is a strong tool for both basic and clinical research on chitinase-like proteins.

Type IV chitinase quantification in four different grape cultivars (Vitis vinifera) in northeast of Iran by an indirect sandwich enzyme-linked immunosorbent assay.

The incidence of grape (Vitis vinifera) allergy in the northeast of Iran is second to melon allergy. Type IV chitinase is one of the major grape allergens. The current study investigates the level of type IV chitinase in four grape variants for the first time in Khorasan Razavi Province using a highly sensitive sandwich enzyme-linked immunosorbent assay (ELISA). This assay was developed using a polyclonal antibody as a capture antibody and monoclonal antibody as a secondary one. Finally, the amount of type IV chitinase was measured by the validated ELISA test. The sensitivity of the developed sandwich ELISA is 16 ± 0.05 ng/ml, and its mean coefficients of intraday and interday variations are <5% and <15%, respectively. The recovery of the designed ELISA is 64 ± 0.9 %. The assessments showed that the highest level of type IV chitinase was 39.7 ± 2.3 µg/g in Peykani grape, whereas in the Sultana cultivar, it was 1.76 ± 0.1 µg/g. According to the data, the level of type IV chitinase is variable in different cultivars, and hence, it will be helpful for clinicians to recommend a less allergenic variety to the patient.

Chitosan and chitosan nanoparticles induced expression of pathogenesis-related proteins genes enhances biotic stress tolerance in tomato.

The aim of this work was to evaluate the possibility of control of wilt disease caused by Fusarium andiyazi through chitosan (CS) and chitosan nanoparticles (CNPs). In the present study, the expression pattern of pathogenesis-related (PR) proteins genes such as PR-1, PR-2 (ß-1,3-glucanase), PR-8 (chitinase), and PR-10 was analyzed using real-time RT-PCR. In vitro studies showed that among different concentrations (0.1-5.0 mg/ml), 5.0 mg/ml concentration of CS and CNPs produced maximum inhibition of radial mycelial growth, 54.8% and 73.81%, respectively. Also, upregulated expression of ß-1,3-glucanase, chitinase, PR-1 and PR-10 genes were recorded with 1.48, 1.15, 1.15, and 1.41, fold expression in 24 hpi, respectively, in plants inoculated with CNPs. The most significant up-regulation was observed in transcript profile of SOD that showed 4.5-foldexpression, at 48 hpi. Therefore, our results confirmed that CS and CNPs induced up-regulation of PR-proteins and antioxidant genes might play a significant role for successful biocontrol.

A chitinase-like protein from Sarcoptes scabiei as a candidate anti-mite vaccine that contributes to immune protection in rabbits.

BACKGROUND: Scabies is caused by Sarcoptes scabiei burrowing into the stratum corneum of the host's skin and is detrimental to the health of humans and animals. Vaccines are an attractive alternative to replace the acaricides currently used in their control. METHODS: In the present study, the S. scabiei chitinase-like protein 5 (SsCLP5) was characterized and recombinant SsCLP5 (rSsCLP5) was evaluated as a candidate vaccine protein for anti-mite protection in rabbits. The expression, characterization and immunolocalization of SsCLP5 were examined. Vaccination experiments were performed on three test groups (n = 12 per group) immunized with purified rSsCLP5. Control groups (n = 12 per group) were immunized with PBS, QuilA saponin or empty vector protein. After challenge, the inflammatory reaction and skin lesions were graded and rSsCLP5 indirect ELISA was used to detect antibody IgG levels in serum samples at the time of vaccination and post-challenge. RESULTS: The results showed that rSsCLP5 had high immunoreactivity and immunogenicity. In S. scabiei, SsCLP5 had a wide distribution in the chewing mouthpart, legs and exoskeleton, especially the outer layer of the exoskeleton. Vaccination with rSsCLP5 resulted in 74.3% (26/35) of rabbits showing no detectable lesions after challenge with S. scabiei. CONCLUSIONS: Our data demonstrate that rSsCLP5 is a promising candidate for a recombinant protein-based vaccine against S. scabiei. This study also provides a method for studying scabies vaccine using rabbit as an animal model and a basis for screening more effective candidate proteins.

Pomegranate chitinase III: Identification of a new allergen and analysis of sensitization patterns to chitinases.

Allergy to pomegranate is often associated with severe symptoms. Two allergens have previously been described: 9k-LTP Pun g 1 and pommaclein Pun g 7. This study describes the isolation of a chitinase III, identified by direct protein sequencing and mass spectrometry. It is a 29-kDa protein showing 69% sequence identity with the latex hevamine and IgE binding in dot blotting, immunoblotting and FABER®test. Chitinase-specific IgE were detected in 69 of 357 patients sensitized to one or more pomegranate allergenic preparations present on the FABER®test. Using this test, 19.2% of the patients sensitized to kiwifruit chitinase IV were also sensitized to pomegranate chitinase III, rather than to latex chitinase I (7.2%) with which it shares the N-terminal hevein-like domain. In conclusion, a new allergen has been identified, contributing to improving food allergy diagnosis. This study reveals the important role of chitinases III and IV as allergy sensitizers and prompts further investigations.

Acidic mammalian chitinase tuning after enteric helminths eradication in inflammatory respiratory disease patients.

AIM: This study aimed at investigating the presence of intestinal parasitic infections in inflammatory respiratory diseases patients during the disease attack, and measuring the acidic mammalian chitinase (AMCase) gene expression in blood before and after infection eradication. METHODOLOGY: This case-control study included 123 inflammatory respiratory diseases patients and 120 apparently healthy individuals. Repeated stool examination was done, while total and specific IgE were measured. AMCase gene expression was analysed by real time-polymerase chain reaction (RT-PCR). RESULTS: Infection was detected in 32.5% of the diseased and 23.25% of the healthy individuals. Higher rate of the helminthic infection was detected (23.57) in comparison to the protozoal (12.19%) in the patients. A significantly higher rate of infection with the chitin-rich helminths "Enterobius vermicularis & Hymenolepis nana" and level of anti-Dermatophagoide-IgE were reported in the patients (14.63%, 6.5% and 23.57%, respectively). AMCase expression was significantly higher in helminths-infected patients than the noninfected, or protozoa infected. After infection eradication, AMCase expression significantly declined in the previously helminth-infected patients (mean ± SD = 13.9 ± 3.918 before and 4.515 ± 1.93 after), but insignificantly affected in the protozoa infected (mean ± SD = 2.095 ± .285 before and 2.675 ± 1.181 after). CONCLUSION: Chitin-rich intestinal helminths are suspected to precipitate Th2-immune response in remote tissues by enhancing systemic AMCase expression through intestinal mucosa and macrophages irritation.

Expression of M2 macrophage markers YKL-39 and CCL18 in breast cancer is associated with the effect of neoadjuvant chemotherapy.

PURPOSE: High activity of enzyme TOP2a in tumor cells is known to be associated with sensitivity to anthracycline chemotherapy, but 20% of such patients do not show clinical response. Tumor microenvironment, including tumor-associated macrophages (TAM), is an essential factor defining the efficiency of chemotherapy. In the present study, we analyzed the expression of M2 macrophage markers, YKL-39 and CCL18, in tumors of breast cancer patients received anthracycline-based NAC. METHODS: Patients were divided into two groups according to the level of doxorubicin sensitivity marker TOP2a: DOX-Sense and DOX-Res groups. Expression levels of TOR2a, CD68, YKL-39 and CCL18 genes were analyzed by qPCR, the amplification of TOR2a gene locus was assessed by the microarray assay. Clinical and pathological responses to neoadjuvant chemotherapy were assessed. RESULTS: We found that the average level of TOP2a expression in patients of DOX-Sense group was almost 10 times higher than in patients of DOX-Res group, and the expression of CD68 was 3 times higher in the DOX-Sense group compared to DOX-Res group. We demonstrated that expression levels of M2-derived cytokines but not the amount of TAM is indicative for clinical and pathological chemotherapy efficacy in breast cancer patients. Out of 8 patients from DOX-Sense group who did not respond to neoadjuvant chemotherapy (NAC), 7 patients had M2+ macrophage phenotype (YKL-39+CCL18- or YKL-39-CCL18+) and only one patient had M2- macrophage phenotype (YKL-39-CCL18-). In DOX-Res group, out of 14 patients who clinically responded to NAC 9 patients had M2- phenotype and only 5 patients had M2+ macrophage phenotype. Among pathological non-responders in DOX-Sense group, 19 (82%) patients had M2+ tumor phenotype and only 4 (18%) patients had M2- phenotype. In DOX-Res group, all 5 patients who pathologically responded to NAC had M2 phenotype (YKL-39-CCL18-). Unlike the clinical response to NAC, the differences in the frequency of M2+ and M2- phenotypes between pathologically responding and non-responding patients within DOX-Sense and DOX-Res groups were statistically significant. CONCLUSIONS: Thus, we showed that in patients with breast cancer who received anthracycline-containing NAC the absence of clinical response is associated with the presence of M2+ macrophage phenotype (YKL-39-CCL18 + or YKL-39 + CCL18-) based on TOP2a overexpression data.

A chitinase from pacific white shrimp Litopenaeus vannamei involved in immune regulation.

Chitinases are a group of hydrolytic enzymes that hydrolyze chitin and widely exist in organisms. Studies in mammals have demonstrated that chitinases play important roles in regulation of humoral and cellular immune responses. In arthropods, although it is well known that chitinases are involved in growth, molting and development, the current knowledge on the role of chitinases in immunity, especially in immune regulation, remains largely unknown. In this study, a chitinase (LvChi5) from Litopenaeus vannamei was representatively selected for studying its immune function. The start codon of LvChi5 was corrected by 5'RACE analysis and its protein sequence was reanalyzed. LvChi5 contains a catalytic domain and a chitin binding domain and shows no inhibitory effect on growth of bacteria in vitro. However, in vivo experiments demonstrated that silencing of LvChi5 increased the mortality of shrimp infected with white spot syndrome virus (WSSV) and Vibro parahaemolyticus and significantly upregulated the load of pathogens in tissues. The expression of various immune related genes, including transcription factors, antimicrobial peptides and other functional proteins with antibacterial and antiviral activities, was widely changed in LvChi5 silencing shrimp. Moreover, the recombinant LvChi5 protein could enhance the phagocytic activity of hemocytes against bacteria. These suggested that shrimp chitinase could play a role in regulation of both humoral and cellular immune responses in shrimp.

Characterization and expression analysis of a chitinase gene (PmChi-5) from black tiger shrimp (Penaeus monodon) under pathogens infection and ambient ammonia-N stress.

Chitinases are crucial enzymes for crustaceans. Previous researches had already revealed that chitinases play important roles in digestion, molting and defense against viruses. In the present study, a chitinase cDNA was identified from black tiger shrimp (Penaeus monodon) and designated as PmChi-5. The full-length PmChi-5 cDNA was 2860 bp in size, containing an open reading frame (ORF) of 1731 bp that encoded a protein of 576 amino acids with a deduced molecular weight of 64.8 kDa. Expression of the PmChi-5 mRNA was ubiquitously detected in all selected tissues, with the highest level in the gill and hepatopancreas. PmChi-5 was expressed throughout the whole larvae stages, and the highest level at Mysis3 stage, which indicated that PmChi-5 may be involved in larval metamorphosis. After challenged with Streptococcus agalactiae and Vibrio harveyi, the transcripts of PmChi-5 were found to be up-regulated significantly both in hepatopancreas and gill. Besides, the ammonia nitrogen stress treatment was also carried out, PmChi-5 transcripts were significantly changed in hepatopancreas and gill. The results showed that PmChi-5 may be involved in molting, larval metamorphosis, the immune defenses to pathogens infection and ammonia-N stress.

A CRISPR/Cas9-mediated mutation in chitinase changes immune response to bacteria in Exopalaemon carinicauda.

Chitinase, belonging to family 18 glycosyl hydrolase, is a multi-gene family and it has many functions. Generation of loss-of-function mutant targeting an interesting gene is a common way to clarify its function based on reverse genetics. In this study, we first reported the immune defense of a chitinase gene (EcChi4) in Exopalaemon carinicauda using its EcChi4-deletion mutant. EcChi4 was predominantly expressed in hepatopancreas and was upregulated after challenge with Vibrio parahaemolyticus or Aeromonas hydrophila. After knockout EcChi4 gene using CRISPR/Cas9 tool, the prawns in EcChi4-deletion group had significant higher mortality than those in wild-type group when the prawns were challenged with V. parahaemolyticus or A. hydrophila. In conclusion, we first demonstrate the function of a chitinase gene in immune defense of E. carinicauda by performing directed, heritable gene mutagenesis. In the future, CRISPR/Cas9 should be widely applicable as a feasible means for gene editing in E. carinicauda for the study of important biological questions that cannot be easily addressed in other decapods.

Characterization of maize chitinase-A, a tough allergenic molecule.

Food allergies are recognized as an increasing health concern. Proteins commonly identified as food allergens tend to have one of about 30 different biochemical activities. This leads to the assumption that food allergens must have specific structural features which causes their allergenicity. But these structural features are not completely understood. Uncovering the structural basis of allergenicity would allow improved diagnosis and therapy of allergies and would provide insights for safer food production. The availability of recombinant food allergens can accelerate their structural analysis and benefit specific studies in allergology. Plant chitinases are an example of food allergenic proteins for which structural analysis of allergenicity has only partially been reported. The recombinant maize chitinase, rChiA, was purified from Pichia pastoris extracellular medium by differential precipitation and cation exchange chromatography. Enzyme activity was evaluated by halo-assays and microcalorimetric procedures. rChiA modeling was performed by a two-step procedure, using the Swiss-Model server and Modeller software. Allergenicity of rChiA was verified by immunoblot assays with sera from allergic subjects. rChiA is active in the hydrolysis of glycol chitin and tetra-N-acetylchitotetraose and maintains its activity at high temperatures (70°C) and low pH (pH 3). The molecule is also reactive with IgE from sera of maize-allergic subjects. rChiA is a valuable molecule for further studies on structure-allergenicity relationships and as a tool for diagnosing allergies.