Allergens involved in the cross-reactivity of Aedes aegypti with other arthropods.

BACKGROUND: Cross-reactivity between Aedes aegypti and mites, cockroaches, and shrimp has been previously suggested, but the involved molecular components have not been fully described. OBJECTIVE: To evaluate the cross-reactivity between A aegypti and other arthropods. METHODS: Thirty-four serum samples from patients with asthma and/or allergic rhinitis were selected, and specific IgE to A aegypti, Dermatophagoides pteronyssinus, Dermatophagoides farinae, Blomia tropicalis, Periplaneta americana. and Litopenaeus vannamei was measured by enzyme-linked immunosorbent assay. Cross-reactivity was investigated using pooled serum samples from allergic patients, allergenic extracts, and the recombinant tropomyosins (Aed a 10.0201, Der p 10, Blo t 10, Lit v 1, and Per a 7). Four IgE reactive bands were further characterized by matrix-assisted laser desorption/ionization tandem time of flight. RESULTS: Frequency of positive IgE reactivity was 82.35% to at least one mite species, 64.7% to A aegypti, 29.4% to P americana, and 23.5% to L vannamei. The highest IgE cross-reactivity was seen between A aegypti and D pteronyssinus (96.6%) followed by L vannamei (95.4%), B tropicalis (84.4%), and P americana (75.4%). Recombinant tropomyosins from mites, cockroach, or shrimp inhibited the IgE reactivity to the mosquito at a lower extent than the extracts from these arthropods. Several bands of A aegypti cross-reacted with arthropod extracts, and 4 of them were identified as odorant binding protein, mitochondrial cytochrome C, peptidyl-prolyl cis-trans isomerase, and protein with hypothetical magnesium ion binding function. CONCLUSION: We identified 4 novel cross-reactive allergens in A aegypti allergenic extract. These molecules could influence the manifestation of allergy to environmental allergens in the tropics.

Identification and Characterization of IgE-Binding Tropomyosins in Aedes aegypti.

BACKGROUND: The mosquito Aedes aegypti is a potential source of important clinically relevant allergens. However, the allergenicity and cross-reactivity of most of these has not been fully described. METHODS: Natural wild-type mosquito tropomyosin was purified by size exclusion and anionic-exchange chromatography from an A. aegypti extract. Further characterization was accomplished by MALDI-TOF/TOF. Two recombinant variants of tropomyosin were obtained by expression in Escherichia coli. Specific IgE measurement by ELISA and skin tests for mosquito extract were performed in 12 patients with asthma or allergy rhinitis residing on the Caribbean island of Martinique. Cross-reactivity between natural A. aegypti tropomyosin and recombinant tropomyosins from A. aegypti, house dust mite, shrimp and Ascaris lumbricoides was analyzed by ELISA competition. RESULTS: Four variants of natural tropomyosin were purified. A band of 32 kDa in SDS-PAGE representing 2 tropomyosin variants (Aed a 10.0101 and Aed a 10.0201) reacted with specific IgE of 4 of the 12 (33%) allergic patients and with rabbit polyclonal anti-shrimp tropomyosin. A high degree of cross-reactivity (60-70%) was detected between natural mosquito tropomyosin and Blo t 10, Der p 10 and Lit v 1, and a lower degree with Asc l 3 from A. lumbricoides (<30%). rAed a 10.0101 inhibited IgE binding to natural A. aegypti tropomyosin; however, rAed a 10.0201 showed a low inhibitory capacity. CONCLUSION: Tropomyosin is a new IgE-binding protein from A. aegypti. Two of the 4 variants identified showed different degree of cross-reactivity with tropomyosins from other arthropods. The potential allergenic role of each variant should be further investigated.

Dermatitis de contacto, rinoconjuntivitis y asma bronquial

La alergia respiratoria del esma es una entidad conocida, en la que se vienen encontrando cada vez más factores desencadenantes. Se describen un paciente afectado de asma bronquial y dermatitis de contacto y tres de rinoconjuntivitis intensa tras contacto con la cebolla paiteña. En los cuatro pacientes se realizan pruebas cutáneas (prick, prick-prick y patch test), pruevas de provocación bronquial nasal y oral y pruebas in vitro para detectar IgE especifica frente a cebolla paiteña y se estudia su reactividad cruzada con otros antigenos. como control de este estudio y para evaluar la prevalencia de sensibilidad cutánea a la cebolla paiteña, se realizó el prick-prick test a 106 sujetos escogidos al azar en nuestra consulta. En los cuatro pacientes encontramos reacciones positivas en el prick y prick-prick test e IgE especifica frente a cebolla paiteña. Se obtuvieron reacciones positivas en las pruevas de provocación bronquial, oral y patch test y en la provocación nasal y oral. Encontramos además inhibición del CAP a cebolla paiteña consigo misma, polen de gramineas pero no con D. pteronnysinus. Ocho (7.5 por ciento) de los 106 individuos usados como control, tuvieron un prick-prick positivo, dos de ellos con sintomatología sospechosa de alergia. Todos ellos eran alergicos a pólems y/o ácaros. En los sujetos estudiados demostramos que la cebolla paiteña puede ser la causa de asma, rinoconjuntivitis y dermatitis de contacto. El mecanismo implicado parece ser IgE mediado en los dos primeros casos y mediado por células en el último. Se demuestra además reactividad cruzada con los pólems de gramineas.

Conjuntivitis alérgica causada por cromoglicato disódico

Se describen los estudios realizados en un paciente afectado de conjuntivitis aguda tras la administración de un colirio que contenía cromoglicato disódico. Se detectó alergia de tipo I, mediante pruebas cutáneas. Pruebas de provocación conjuntival y detección de IgE específica frente a ésta sustancia.

Urticaria y conjuntivitis aguda causadas por corticoides

Presentamos el caso de dos sujetos sometidos a tratamiento parenteral con los corticoides dexametasona y parametasona (Triniol). A los pocoso minutos de su administración desarrollaron un cuadro urticariforme y uno de ellos ademas una inyeccion conjuntival en el ojo derecho. Fueron sometidos a pruebas cutáneas con todos los componentes del Triniol. Por separado, siendo esta positiva tras la administración intramuscular de 1 ml de la sustancia y negativa con cada uno de los excipientes del preparado. las pruebas "in vitro" destinadas a detectar IgE especifica frente a la parametasona, fueron negativas. Adicionalmente realizamos provocaciones orales y parenterales con otros corticoides encontrando intolerancia a varios de ellos