Sensitization to the fungus Hemileia vastatrix (coffee leaf rust).

BACKGROUND: The aim of the present study was to determine the existence of sensitization to the fungus Hemileia vastatrix (coffee leaf rust) in a sample of the Brazilian population. This fungus attacks coffee plantations, and in some regions of Brazil the concentration of its spores in the air can be very high. METHODS: A total of 378 individuals underwent skin tests (prick and intradermal tests) with H. vastatrix extract. The subjects were divided into four groups according to the occurrence of atopy and the region where they lived (coffee-growing or non-coffee-growing regions), and another group (V) consisted of 50 rural workers employed on coffee plantations. The presence of specific IgE against the fungus H. vastatrix in sensitized individuals was demonstrated in vitro by immunoblotting. RESULTS: There was no statistical difference in comparing the results with intradermal or prick tests. The incidence of positive tests was significantly higher among atopic individuals residing in coffee-growing regions (14.7%). Among rural workers, 10% showed positive tests. Immunoblotting revealed specific IgE against 20 protein bands of H. vastatrix. CONCLUSION: The fungus H. vastatrix may be an important allergen in coffee-producing countries. The sensitization is more frequent among atopic individuals residing in coffee-growing regions.

House dust mites in the city of Lima, Peru.

Since mites are the most common house dust allergens, knowledge about the species most prevalent in a region is important for diagnostic and specific immunotherapy purposes. In order to establish the prevalence of house dust mites in different city districts, 100 house dust samples were collected from different parts of Lima. Lima is a city of tropical climate located along the coast of the Pacific Ocean. The relative air humidity is 80-90% and the various districts studied are located at altitudes ranging from 37-355 meters. The mite Blomia tropicalis was the organism most frequently detected, being present in 59% of the house dust samples. Dermatophagoides pteronyssinus occupied second place (15.9%), followed by Chortoglyphus arcuatus and Tyrophagus putrescentiae. These four mites, taken together, represented more than 90% of the mites detected. No specimen of the species Dermatophagoides farinae was detected. We conclude that B. tropicalis and D. pteronyssinus are the most common house dust mites in Lima. Considering the high prevalence of B. tropicalis in Lima and the fact that its cross-reactivity with antigens of the mites of the family Pyroglyphidae is minimal, we conclude that sensitization to this mite should be investigated separately in allergic patients living in Lima.

Acquired immunity to Africanized honeybee (Apis mellifera) venom in Brazilian beekeepers.

Seventy-eight Brazilian beekeepers who had been stung on average six times per month were studied. Sixty-eight beekeepers (87.1%) showed restricted local clinical reactions; nine individuals (11.5%) had extensive local reactions, and only one (1.2%) suffered anaphylactic shock. The humoral immunologic pattern of these individuals were studied by using immunoenzymatic methods to determine the serum titles of specific IgE and specific IgG4. Three groups of beekeepers presenting different humoral immunologic patterns were identified, in which the predominant pattern was the absence of specific IgE and high levels of specific IgG4 (38.4%). There was a positive correlation between the high levels of specific IgG4 and the number of bee stings. This correlation was not found in either specific or total IgE. The results of the present study suggest: i) the immunologic response to the number of exposures to Africanized honey-bee venom is not related to the number of exposures; and, ii) other nonhumoral and/or nonimmunologic factors may be involved in the reaction to the insect sting, which are responsible for both the clinical symptoms and protection.

Effect of aspirin on beta-receptors in lymphocytes from patients with aspirin-induced asthma.

We studied the effect of aspirin on beta-adrenergic receptors in lymphocytes from three groups of subjects: 5 asthmatic patients presenting sensitivity to aspirin, 10 asthmatic patients with tolerance to aspirin and a control group. Lymphocytes were incubated with aspirin-lysine (36 micrograms/ml). The number of beta-receptors/cell and the dissociation constants (Kd) were assessed by means of [125I]-cyanopindolol (ICYP). There was a decrease in the number of beta-receptors after incubation with aspirin in all asthmatic patients with sensitivity. The differences between mean basal (660 +/- 171 receptors/cell) and postincubation (398 +/- 110 receptors/cell) values were significant (p < 0.05). There were also significant differences (p < 0.01) between basal (23.4 +/- 6 pM) and postincubation (15 +/- 5.1 pM) Kd values, which indicates that the affinity of ICYP increased. In the subjects in the other two groups, aspirin both increased and decreased the number of beta-receptors, but the effects were not significant. It is suggested that in patients with sensitivity, aspirin could induce changes in the plasmatic membrane, thus altering beta-receptors or inducing the release of inflammatory mediators that exert their effect upon these receptors.

Library fungi at the University of São Paulo and their relationship with respiratory allergy.

In this study, we investigated the fungi most frequently found in the air and the books of 28 libraries at the University of São Paulo, Brazil. In a second phase, 314 librarians were questioned about the presence of asthmatic or rhinitic symptoms, and the relationship with the site of work. Forty-nine percent of them reported this type of symptoms and 80% related them to the place of work. In the third stage, librarians underwent intracutaneous tests against the 20 fungi most frequently isolated in libraries. Eighteen librarians presented positive tests, 12 of whom reported rhinitis and 6 of whom were asymptomatic. In 19.5% of symptomatic patients wheals > 15 mm were observed after 6 h, while 9% of the asymptomatic patients presented similar wheals. Fourteen librarians with positive tests underwent tests with each of the 20 fungi constituting the pool. The airborne fungi isolated in libraries are likely to be found anywhere in the city of São Paulo, but they are likely to be present in higher concentrations in libraries, subsequently producing respiratory allergies.

Furosemide inhibits in vitro histamine release induced by antigens and anti-IgE.

We used 56 samples of heparinized blood of patients with asthma and/or allergic rhinitis, which were stimulated with Dermatophagoides pteronyssinus or gramineous pollen and anti-IgE in order to study the effect of furosemide on histamine release in basophils. At the same time, blood samples incubated in furosemide in different concentrations (2.5 microM to 1.49 mM) were also subjected to the same stimuli. Results showed a linear and dose-dependent inhibition of histamine release for antigens (r = 0.96; p < 0.01) and anti-IgE (r = 0.95; p < 0.05), reaching 95% at maximum inhibition. These results support the hypothesis that furosemide may act on mastocytes and basophils, thus inhibiting the release of histamine and other mediators.

Bronchial challenge with aspirin lysine in the diagnosis of asthmatics with sensitization to aspirin and its inhibition by aerosolized furosemide.

We performed bronchial challenge with ASA lysine in 9 patients with a history of aspirin-induced asthma, 4 asthmatics with no history of hypersensitization to aspirin and 4 control subjects. The test consisted of successive inhalations of increasing concentrations of ASA lysine (11.25, 22.5, 45, 90, 180 and 360 mg/ml) and was interrupted when FEV1 showed a decrease of at least 20%. In order to determine the degree of bronchial hyperreactivity, we first carried out a bronchial challenge with histamine. All patients in the group sensitive to aspirin had a positive reaction to ASA lysine, while this was negative for patients in the two control groups. There was no significant correlation between PC20 to histamine and ASA lysine in any of the groups. On the other hand, 6 patients with sensitivity to ASA repeated the bronchial challenge with ASA lysine after previously inhaling furosemide, and in this second test, none of the 6 had a positive reaction. The variation of ASA lysine PC20 in both tests was positive for these patients (p < 0.001).