Interleukin-10 is a natural suppressor of cytokine production and inflammation in a murine model of allergic bronchopulmonary aspergillosis.

We have used interleukin-10 (IL-10) gene knockout mice (IL-10-/-) to examine the role of endogenous IL-10 in allergic lung responses to Aspergillus fumigatus Ag. In vitro restimulated lung cells from sensitized IL-10-/- mice produced exaggerated amounts of IL-4, IL-5, and interferon-gamma (IFN-gamma) compared with wild-type (WT) lung cells. In vivo, the significance of IL-10 in regulating responses to repeated A. fumigatus inhalation was strikingly revealed in IL-10-/- outbred mice that had a 50-60% mortality rate, while mortality was rare in similarly treated WT mice. Furthermore, IL-10-/- outbred mice exhibited exaggerated airway inflammation and heightened levels of IL-5 and IFN-gamma in bronchoalveolar lavage (BAL) fluids. In contrast, the magnitude of the allergic lung response was similar in intranasally (i.n.) sensitized IL-10-/- and wild-type mice from a different strain (C57BL/6). Using a different route of priming (intraperitoneal) followed by one i.n. challenge we found that IL-10-/- C57BL/6 mice had heightened eosinophilic airway inflammation, BAL-IL-5 levels, and numbers of alphabetaT cells in the lung tissues compared with WT mice. We conclude that IL-10 can suppress inflammatory Th2-like lung responses as well as Th1-like responses given the constraints of genetic background and route of priming.

IgE and eosinophil regulation in a murine model of allergic aspergillosis.

Exposure of BALB/c mice to Aspergillus fumigatus (Af), the antigen responsible for causing allergic bronchopulmonary aspergillosis in humans, caused elevated levels of serum immunoglobulin E (IgE) and peripheral blood and lung eosinophilia similar to that observed in the human disease. We have investigated the role of interleukin-4 (IL-4), IL-5 and interferon-gamma in regulating IgE and eosinophilia in the mouse model. Animals were immunized by intraperitoneal injections of soluble Af antigens adsorbed to alum. These animals developed elevated IgE and Af specific IgG1 and were then treated with anticytokine monoclonal antibodies before the final exposure to particulate Af antigens by the intranasal route. The results showed that anti-IL-5 abrogated eosinophilia in mice, while those treated with anti-IL-4 retained the same or reduced IgE levels compared to pretreatment levels. All anti-IL-5, anti-IFN-gamma, and control antibody-treated animals showed enhanced IgE levels. Anti-IFN-gamma treatment of mice resulted in marked enhancement of eosinophilia compared to all other groups. Eosinophil numbers observed in the histological sections of the lungs confirmed the eosinophilia detected in the peripheral blood. These results indicate that the increase in IgE and eosinophils after exposure to Af antigens in BALB/c mice are due to Af-induced production of IL-4 and IL-5 and that both IgE and eosinophilia are independently regulated.

Hyperimmune serum modulates allergic response to spores in a murine model of allergic aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) is a disease in atopic asthmatics characterized by eosinophilia and elevated levels of immunoglobulin E (IgE) and IgG antibodies to the ubiquitous fungus Aspergillus fumigatus (Af). The role of specific antibodies in the disease process is not clear. In this study, BALB/c mice were injected with hyperimmune serum from syngeneic mice exposed to soluble antigen of Af. These mice were then exposed to either Af spores or soluble antigen. Total IgE, Af-specific IgG1 (enzyme-linked immunosorbent assay) in serum, and eosinophils (eosinophil peroxidase assay) in lungs and bone marrow were measured. Histologic sections of lungs were examined for cellular infiltration and morphologic changes. Results indicate a suppression of increase in levels of antibodies and eosinophilia in mice receiving immune serum and exposed to spores compared with controls receiving phosphate-buffered saline treatment. Spores being the primary source of exposure to Af in ABPA, these results are significant in understanding the role of preexisting specific antibodies in patients.

Aspergillus fumigatus antigen induced eosinophilia in mice is abrogated by anti-IL-5 antibody.

A murine model of allergic bronchopulmonary aspergillosis (ABPA), developed by exposure to Aspergillus fumigatus antigens, demonstrated eosinophilia of peripheral blood (PB), bone marrow (BM), and lung. The eosinophilia was abrogated by monoclonal anti-interleukin-5 (IL-5) antibody (TRFK-5) and not by an isotype control antibody (GL 113). Eosinophils in PB were enumerated from stained smears and their relative increase or decrease in cells from BM and lung was determined by an eosinophil peroxidase (EPO) assay (measured in optical density). Intraperitoneal injection of TRFK-5 in mice exposed to A. fumigatus antigen produced a significant reduction in eosinophils (PB 6.6 +/- 1.14% vs. 3.8 +/- 0.8%, P < .01) and EPO production in BM (0.935 +/- 0.03 vs. 0.615 +/- 0.02, P < .001). A similar reduction in EPO production in the lung (0.691 +/- 0.12 vs. 0.495 +/- 0.05, not significant) was also reflected in the histopathology for the different groups of mice. These findings confirming the role of IL-5 in eosinophilia, although not surprising, are significant in elucidating the immunopathogenesis of ABPA in the murine model. We conclude that in this model, eosinophilia may be due largely to the Th2 cytokine -IL-5 induced by A. fumigatus antigens.

Immunochemical studies of a purified antigen from Micropolyspora faeni.

A pure antigen fraction was isolated from the crude culture filtrate of Micropolyspora faeni by gel filtration and affinity chromatography. The isolated antigen has a mol. wt of approximately 16,000 and an isoelectric point of pH 3.8. The major amino acid content of this fraction includes glycine, glutamic acid, aspartic acid and alanine. This antigen fraction reacted with the sera of all 15 farmer's lung patients and 20 asymptomatic farmers with circulating anti-M. faeni antibodies. An ELISA method was developed using the purified antigen to detect specific circulating antibodies against M. faeni in farmer's lung patients.

Unique and shared IgE epitopes of Hev b 1 and Hev b 3 in latex allergy.

Of the several latex proteins cloned and expressed, the rubber elongation factor, Hev b 1, and the closely related Hev b 3, represent two major allergens associated with latex allergy. Although both allergens demonstrated IgE binding with sera from latex allergic patients, it was not known whether these two molecules shared any epitopes. Hence, in the present study using health care workers (HCW) and spina bifida (SB) patients with latex allergy, we investigated the IgE binding epitopes in Hev b 1 and Hev b 3. Recombinant Hev b 1 and Hev b 3 were expressed in a prokaryotic expression system, while overlapping decapeptides of Hev b 1 and Hev b 3 were synthesized on derivatized cellulose membrane. Eight IgE binding epitopes for Hev b 1 and eleven for Hev b 3 were identified using sera from latex allergic patients with SB. On further analysis of synthetic peptides encompassing these epitopes, similar IgE antibody reactivity was demonstrated with three Hev b 1 epitopes b1E3, b1E5, b1E6 and two Hev b 3 epitopes; b3E10 and b3E 11. For Hev b 1, a unique IgE binding epitope was identified in the region of amino acid residues 16-25. In competitive ELISA, peptides bIE2 and bIE4 together inhibited 58% of IgE binding of Hev b 1, while b3E5 showed 22% inhibition in the IgE binding of Hev b 3. The results of the present study suggest that the understanding of linear and conformational IgE epitopes in the major latex allergens may provide better insight into the structure-function relationship of the allergens, and may lead to the development of better patient care and management strategies in latex allergy.

Respiratory fungal allergy.

Fungal allergy including allergic rhinitis, conjunctivitis, bronchial asthma, and allergic bronchopulmonary mycoses results from exposure to spores. In this review we have dealt with the common allergenic fungi and allergens, immunopathogenesis, diagnostic assays, and the possible control of allergy in the future based on epitope-specific immunotherapy and vaccination.

Immunotherapy of allergic bronchopulmonary aspergillosis: a clinical and experimental approach.

Allergic bronchopulmonary aspergillosis (ABPA) is a severe allergic pulmonary complication caused by the saprophytic fungus Aspergillus fumigatus. The present review examines the pathogenesis of this disease describing in detail the role of innate and acquired immunity in the induction of sensitivity to A.fumigatus. Different approaches in developing specific immunotherapeutic treatments such as induction of anergy, regulatory cells, a switch from Th2 to Th1 type of immune response, CpG and genetic immunization and the usage of altered peptides or modified allergens are critically examined.

Early detection of hypersensitivity pneumonitis in office workers.

Symptoms of hypersensitivity pneumonitis in three employees in an office building led to an investigation of their work environment. An open spray water air cooling system was implicated when inhalation challenge with the spray water caused acute illness in one of them. A questionnaire survey of the 4,023 co-workers identified 48 other suspect cases, and laboaratory studies confirmed hypersensitivity pneumonitis in three additional workers of this group. A significant change in pulmonary function, occurring only after exposure to the work environment, was the most useful laboratory finding and was found in five workers with no other pulmonary abnormalities, but not is asymptomatic workers or controls, since five of the six patients with hypersensitivy pneumonitis worked in offices cooled by the spray water system and since three had positive responses to inhalation challenge, use of the spray water system was discontinued. The affected workers improved after they were removed from the office complex.

Interaction of Aspergillus fumigatus spores and pulmonary alveolar macrophages of rabbits.

The in vitro and in vivo interaction of rabbit pulmonary alveolar macrophages (PAM) and Aspergillus fumigatus spores was studied. In vitro experiments showed that PAM from normal rabbits failed to appreciably kill A. fumigatus spores in 4 hours, while A. flavus and A. niger spores were destroyed effectively. Prior opsonization of the spores with normal rabbit serum, rabbit anti-A. fumigatus serum, complement or lung lavage fluid has no profound enhancing effect on the phagocytosis or killing of the spores. Activated macrophages, however, killed slightly more spores than normal macrophages. When A. fumigatus spores were injected intratracheally into rabbits, no dissemination to organs other than the lungs was detected during the first hour, while dissemination to the liver, spleen and kidneys was observed one hour after the inoculation. Free spores in the bronchoalveolar washings and ingested spores in macrophages diminished in 4 hours, while spores in the lung homogenate increased considerably.