Oxidative activity of ammonium persulfate salt on mast cells and basophils: implication in hairdressers' asthma.

BACKGROUND: Persulfate salts are components of bleaching powders widely used by hairdressers during hair-bleaching procedures. Hairdressers are at high risk for occupational asthma and rhinitis, and ammonium persulfate is the main etiologic agent. OBJECTIVE: To explore the effects of ammonium persulfate on human albumin, mast cells, and basophils in order to evaluate a possible effect of ammonium persulfate oxidizing activity in the mechanism of ammonium persulfate-induced occupational asthma. METHODS: High-performance liquid chromatography/mass spectrometry was performed on ammonium persulfate-incubated human albumin. The activation of LAD2 human mast cell and KU812 human basophil cell lines incubated with ammonium persulfate was evaluated. CD63 expression on persulfate-in-vitro-incubated blood basophils from nonexposed healthy controls (n = 31) and hairdressers with work-related respiratory symptoms (n = 29) was assessed by flow cytometry. RESULTS: No persulfate-albumin conjugate was found. An oxidative process on tryptophan and methionine was detected. Ammonium persulfate induced reactive oxygen species (ROS) generation and the degranulation of LAD2 and KU812 cells. Human basophils from healthy controls, incubated in vitro with ammonium persulfate, showed increased CD63 expression and ROS production. In hairdressers with ammonium persulfate-caused occupational asthma (positive persulfate challenge), basophil-CD63 expression was higher than in those with a negative challenge and in healthy controls. CONCLUSIONS: Ammonium persulfate incubated with human albumin did not generate any adduct but oxidized some amino acids. This oxidizing activity induced human mast cell and basophil activation which might be crucial in the mechanism of persulfate-induced occupational asthma and rhinitis.

Affinity purification of egg-white allergens for improved component-resolved diagnostics.

BACKGROUND: Egg is a common cause of food-allergic reactions, especially among young children. Some egg-allergic patients do, however, tolerate heated egg products and component-resolved diagnostics (CRD) may facilitate prediction of different disease manifestations. Commercially available preparations of the egg-white allergens, ovomucoid, ovalbumin, conalbumin and lysozyme, have been reported to contain impurities which interfere with accurate CRD. METHODS: Commercial preparations of the 4 egg-white allergens were characterized using allergen-specific monoclonal chimeric human/mouse IgE antibodies in experimental ImmunoCAP® tests. Further purification of commercial ovomucoid, ovalbumin and conalbumin preparations was performed by chromatography based on affinity to monoclonal antibodies. Purity was monitored by size exclusion chromatography, SDS-PAGE, Western blotting and experimental ImmunoCAP tests using allergen-specific chimeric IgE antibodies. IgE reactivity to the highly purified egg components was analyzed in 83 samples from egg white-sensitized individuals. RESULTS: Preparations of commercially available ovomucoid, ovalbumin and conalbumin were found to contain other egg allergens which were removed by chromatographic purification. No impurities were detected in the commercial lysozyme preparation. Previously unknown complexes between the target allergens and contaminating allergens were detected and removed by affinity chromatography. IgE reactivity to ovalbumin was most common in the analyzed samples (87%), followed by ovomucoid (72%), conalbumin (69%) and lysozyme (58%). CONCLUSIONS: In this study we demonstrate the advantage of using monoclonal antibodies for purification, and monoclonal chimeric IgE antibodies for characterization, of egg allergens intended for CRD. Our study also established that ovalbumin, ovomucoid, conalbumin and lysozyme are all major allergens.

Cat IgA, representative of new carbohydrate cross-reactive allergens.

BACKGROUND: Allergens from cat are among the most potent elicitors of allergic disease. Four cat allergens have been identified; however, evidence indicates the existence of additional allergens. OBJECTIVE: In this study, we evaluated IgE sensitization to IgA from cat. METHODS: Sera from cat-sensitized patients (n = 81) were analyzed for IgE antibodies to purified cat IgA in the Pharmacia CAP System. Indirect ELISA was performed with cat IgA, cat IgM, and deglycosylated cat IgA. Competitive inhibition ELISA was performed with cat IgA, cat IgM, calf intestine alkaline phosphatase (CIP), and cat serum albumin on solid phase bound cat IgA. IgE reactivity was also evaluated on membrane blotted cat IgA. RESULTS: Thirty-eight percent (31/81) of the cat-sensitized sera were ImmunoCAP-positive to cat IgA. Indirect ELISA demonstrated a high correlation between IgE reactivity to cat IgA and cat IgM (r = 0.94; P < .001). Very low responses were observed to deglycosylated IgA. Strong inhibition of cat IgA was observed in all sera after preincubation with cat IgA and cat IgM. Inhibition was also observed in most sera after preincubation with CIP. Immunoblotting demonstrated that the IgE reactivity was mainly directed to the heavy chain of IgA. CONCLUSION: This study has revealed a new allergen, cat IgA, containing a novel group of cross-reactive epitopes depending on carbohydrates also present on IgM and partially on CIP. CLINICAL IMPLICATIONS: This new group of cross-reactive carbohydrate IgE epitopes should be taken into consideration when diagnosing patients with suspected animal allergy.