RESUMO
BACKGROUND: Blomia tropicalis is a common mite found in the house dust of many tropical countries including Venezuela. The prevalence of skin test and specific serum immunoglobulin (Ig)E reactivity to B. tropicalis in Venezuela has not been previously evaluated. METHODS: In the present study we evaluated the skin reactivity by skin prick test and specific IgE by a multiple antigen blot assay, against B. tropicalis and Dermatophagoides pteronyssinus, in a group of 115 subjects who attended the Allergy Clinic of the Institute of Biomedicine, Caracas, Venezuela, and we studied possible cross reactions between similar proteins of these two mites. RESULTS: One hundred and six patients with persistent allergic respiratory symptoms showed a positive skin prick test to at least one of the mite extracts, with the frequency of positive reactions to B. tropicalis being as high as to D. pteronyssinus. Twelve patients reacted only to D. pteronyssinus and 13 different patients only to B. tropicalis. Specific IgE to each of the mite extracts was found with similar frequency, and the results coincided with the skin test reactivity. CONCLUSIONS: The study indicated the importance of including B. tropicalis in routine diagnostic testing in tropical and sub-tropical situations.
Assuntos
Ácaros/imunologia , Hipersensibilidade Respiratória/diagnóstico , Adulto , Alérgenos/efeitos adversos , Alérgenos/imunologia , Animais , Antígenos de Dermatophagoides/imunologia , Asma/etiologia , Asma/imunologia , Reações Cruzadas/imunologia , Reações Cruzadas/fisiologia , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Humanos , Imunoglobulina E/sangue , Imunoglobulina E/imunologia , Masculino , Pyroglyphidae/imunologia , Hipersensibilidade Respiratória/imunologia , Rinite Alérgica Perene/imunologia , Testes Cutâneos/métodos , VenezuelaRESUMO
Intestinal helminths are among the most common infectious organisms of humans, particularly in tropical regions, and can induce the production of large quantities of IgE antibody. Part of this response is directed against the helminths own antigens, but a polyclonal stimulation also occurs that may increase the allergic reactivity toward environmental allergens. The importance of this in the symptomatology of asthma in these regions is, however, uncertain. In the present study we evaluated the effect of regular anthelminthic treatment with albendazol for 1 yr on a group of asthmatic patients in a zone in which these parasites are endemic. The number of asthmatic crises, need for maintenance therapy with inhaled steroids, and use of inhaled beta 2-agonists were compared both with those in the year prior to the study for the treated patients, and with those in a group of asthmatic subjects evaluated in parallel, but in whom the parasitic infections were not controlled. Significant improvement in all of these indicators of clinical status occurred in the treated group, not only for the period of anthelminth administration, but also for the year following. However, after 2 yr without treatment, the severity of asthma reverted to the initial state. No significant changes were observed in the control group over the entire period of evaluation. At the beginning of the study, the patients' pulmonary function was below the levels predicted for normal individuals, but this was not changed by the anthelminthic treatment. The patients' total serum IgE levels, which were elevated at the beginning of the study, were significantly diminished by the anthelminth administration, as were the specific IgE antibody levels and positivity in skin tests for immediate hypersensitivity to the common environmental allergen Dermatophagoides sp. However, the specific response to Ascaris lumbricoides, a common helminth in the area, was maintained despite treatment. These results indicate that intestinal helminthic infections can contribute to the clinical symptoms of asthma in an endemic situation. This may occur via a direct response to the parasite and/or a nonspecific potentiation of allergic reactivity to environmental allergens.
Assuntos
Albendazol/uso terapêutico , Anti-Helmínticos/uso terapêutico , Asma/etiologia , Helmintíase/complicações , Adolescente , Alérgenos , Animais , Antígenos de Dermatophagoides , Antígenos de Helmintos/imunologia , Ascaris lumbricoides/imunologia , Asma/imunologia , Doenças Endêmicas , Feminino , Glicoproteínas , Helmintíase/tratamento farmacológico , Helmintíase/imunologia , Humanos , Imunoglobulina E/sangue , Masculino , Ácaros/imunologia , Testes de Função RespiratóriaRESUMO
Widely variable prevalences of allergic diseases have been reported in tropical populations, and this has been suggested to be due to effects of the nonspecific polyclonal stimulation of IgE synthesis caused by the helminthic infections that are endemic in these areas. Since 1980, we have been evaluating the allergic reactivity of different socioeconomic sectors of the population of tropical Venezuela (lat. 2-12 degrees N), and in the present study analyze the overall results obtained in the laboratory evaluation of children (5-15 years of age) belonging to these groups. Children of medium-high socioeconomic level (M-HSEL), who experience occasional helminthic infections, have moderately high total serum IgE levels, and have elevated skin test positivities and specific IgE levels against environmental allergens. Persons of low socioeconomic level, in the urban, and particularly rural situation experience frequent helminthic infection, and have highly elevated total serum IgE levels. In contrast to the M-HSEL, the majority of these children have detectable specific IgE antibody against a variety of inhalant allergens, but relatively few have high levels, and their skin test positivity is also low. In these frequently parasitized persons, evidence of saturation of mast cell Fc epsilon receptors was found by tests of passive sensitization. We propose, therefore, that helminthic parasites have a biphasic effect on allergic reactivity; occasional infections are stimulatory, via their nonspecific potentiation of IgE synthesis against environmental allergens, and frequent infections are suppressive due to the widely polyclonal stimulation that they cause, resulting in both diminished specific antibody production against any given allergen and mast cell Fc epsilon receptor saturation.