Hongyung Choi

Particulate Aspergillus fumigatus antigens elicit a TH2 response in BALB/c mice.

BACKGROUND In order to understand the immunoregulation in allergic aspergillosis, a murine model was developed by exposing animals to particulate and soluble antigens of Aspergillus fumigatus. METHODS BALB/c mice were exposed to soluble Aspergillus antigen intranasally. Animals showing moderate levels of IgE were subsequently exposed to soluble antigen or antigen conjugated to polystyrene beads intranasally. The IgE and IgG1 in the sera and the eosinophils in the blood and lungs were studied. The spleen and lung mononuclear cells were stimulated with both concanavalin A and antigen and evaluated for production of interleukin (IL)-4, IL-5, IL-10, and interferon-gamma. RESULTS Animals exposed to particulate antigens showed more elevated serum IgE levels and increased numbers of eosinophils in the blood and lungs than those exposed to soluble antigen. Lung cell cultures from animals exposed to particulate antigens when stimulated with Aspergillus produced IL-4 and IL-5, indicating a TH2 type of response. Animals exposed to soluble antigens showed a weaker TH2 response, as evidence by low IgE levels in sera, fewer eosinophils in the blood, and low levels of cytokine production from lung and spleen cells. CONCLUSION The results indicate that the physical nature of the antigen may have a major role in determining the type of immune response of the host.

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‐γ 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‐γ, and control antibody–treated animals showed enhanced IgE levels. Anti–IFN‐γ 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. J. Leukoc. Biol. 56: 593–598; 1994.

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‐inter‐leukin‐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 histopathol‐ogy for the different groups of mice. These findings confirming the role of IL‐5 in eosinophilia, although not surprising, are significant in elucidating the immu‐nopathogenesis 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.

Anti-interleukin (IL)-4 and -IL-5 antibodies downregulate IgE and eosinophilia in mice exposed to Aspergillus antigens.

The effect of multiple divided doses compared with single‐dose injections of antibodies to murine interleukin (IL)‐4 and IL‐5 in their respective downregulation of IgE and eosinophilia developing in a model of allergic aspergillosis is investigated. BALB/c mice were exposed to Aspergillus fumigatus antigens (Af) before and along with anticytokine antibodies. The kinetics of blood eosinophils, eosinophil peroxidase (EPO) in bone‐marrow cells, scrum levels of IgE and Af‐specific antibodies, Af‐induced cytokine production and mRNA, and lung histology were studied. The results indicate that only multiple anti‐IL‐5 antibodies were effective in maintaining baseline levels of blood eosinophils. Multiple anti‐IL‐4 antibodies also downregulated eosinophils in the bone marrow, lung, and peripheral blood, although to a lesser extent than in anti‐IL‐5 antibody‐injected mice. Significant correlation between the EPO activity and the eosinophil numbers in anticytokine antibody‐treated mice was observed. The different anti‐IL‐4 antibody treatments downregulated IgE to the same extent. We conclude that multiple divided doses of anti‐IL‐5 antibodies arc required to sustain normal eosinophil levels in murine allergic aspergillosis. This information may be significant in the therapy of pulmonary allergic diseases.

Latex Antigens Induce IgE and Eosinophils in Mice

Hypersensitivity to latex proteins has been reported with increasing frequency in recent years. Elevated levels of latex specific IgE have been detected in the majority of these patients. Severe anaphylaxis and death resulting from latex exposure has also been reported. Nevertheless, the immune mechanism of latex allergy is not fully understood. In this report, we describe a model of latex allergy developed in mice exposed to latex proteins. Animals exposed to latex proteins demonstrated enhanced levels of total IgE, peripheral blood and lung eosinophilia, and elevated levels of serum IL-4 and IL-5. mRNA transcripts of IL-4 and IL-5, but not IFN-gamma, could be demonstrated in spleen lymphocytes. Antibodies to latex belonging to all IgG subclasses were detected in the sera of mice exposed to latex antigens. The histology of the lung showed non-necrotizing granulomas and extensive interstitial chronic inflammatory infiltrates, particularly around bronchioles and small blood vessels. Although this model of latex allergy demonstrates a heterogeneous immunological response, the CD4-positive Th2 cell-mediated response predominated.

Role of Particulate Antigens of Aspergillus in Murine Eosinophilia

OBJECTIVE Allergic bronchopulmonary aspergillosis, a disabling hypersensitivity lung disease, results from inhalation of Aspergillus fumigatus antigens present in contaminated environments. A murine model has been developed to understand the immune mechanism involved in allergic bronchopulmonary aspergillosis. We have investigated the immunoregulatory role of different physical forms of A.fumigatus antigens, such as A.fumigatus spores, soluble antigens. and soluble antigen coupled inert particles, in the model. METHODS BALB/c mice were exposed to soluble A.fumigatus antigens, spores, or inert particles of comparable size to the spores coupled with A.fumigatus soluble antigens. Antibody and eosinophil response, pulmonary pathology, and cytokine expressions were studied. RESULTS Peripheral blood eosinophilia and pulmonary inflammation with influx of eosinophils into the lung was detected more in animals exposed to particulate antigens than in those exposed to soluble antigen. However, the total serum IgE and Aspergillus-specific IgG levels showed only a slight increase in the former groups as opposed to elevated levels in animals exposed to soluble antigen. The cytokine expression in in vitro antigen stimulated spleen cells showed a typical Th2 pattern in all antigen-exposed animals. IL-5 mRNA could be detected in the spleen cells cultured with antigen from all groups of antigen-exposed animals. CONCLUSION Particulate A.fumigatus antigens induced eosinophilia in mice prior to the elevation of serum IgE levels. This pattern of IgE and eosinophilia is reversed with the soluble antigen exposure in this model.

Immune responses to Aspergillus antigen in IL-4-/- mice and the effect of eosinophil ablation

Background: Exposure to Aspergillus fumigatus allergens results in enhanced total serum IgE and peripheral blood eosinophils in mice. The associated pulmonary inflammation and immunologic responses are comparable to those detected in human allergic bronchopulmonary aspergillosis. Allergen‐induced cytokines are thought to regulate the inflammatory and immune responses in these animals.

Immune Response and Airway Reactivity in Wild and IL–4 Knockout Mice Exposed to Latex Allergens

Background: Natural rubber latex has been reported as a major cause of allergy and asthma in a number of individuals. One of the occupational groups most affected by latex allergy are the health care workers who are frequently exposed to natural rubber latex products in their patient care activities. The immunopathogenesis of latex allergy is not well understood. In order to understand the immune mechanism in latex allergy, we have developed a mouse model of latex allergy. Methods: Both wild–type and IL–4 knockout BALB/c mice were challenged intranasally with latex proteins and their immune responses, lung pathology, and airway reactivity were evaluated. Results: The total serum IgE and latex specific IgE, IgG1, and peripheral blood and lung eosinophil levels in wild type BALB/c mice were enhanced by the latex exposure, while no IgE or eosinophil were detected in IL–4 knockout mice. Latex–specific IgG1 levels in the sera were lower in IL–4 knockout animals compared to wild mice. However, latex–specific IgG2a antibody was higher in all the IL–4 knockout mice compared to wild type mice. Both the wild type and IL–4 knockout animals developed increased airway resistance after antigen challenge when compared to control animals, although the airway resistance response of IL–4 knockout animals was attenuated compared to the wild–type animals. The histology of the lungs of these two groups of animals was similar. Conclusion: In spite of the differences in the immune responses in the two groups of mice, there were comparable lung inflammatory responses, suggesting a multifactorial pathogenetic mechanism.

Immunopathologic responses to Aspergillus antigen in interleukin-4 knockout mice

Two strains of interleukin-4 (IL-4) gene knockout mice were studied and compared with wild strains to determine the role of IL-4 in the immunopathogenesis of murine allergic aspergillosis. Animals immunized intraperitoneally were subsequently challenged with Aspergillus antigen intranasally. The animals were evaluated for total serum immunoglobulin E (IgE) levels, Aspergillus-specific IgG antibody isotypes, peripheral blood eosinophils, cytokine and chemokine mRNA transcripts in spleen cells, and pulmonary histology. No serum IgE was detected in animals deficient in the IL-4 gene. Aspergillus-specific IgG1 was detected in all animals, while enhanced levels of IgG2a were detected in IL-4 knockout animals challenged with A. fumigatus antigen. There were no differences in the peripheral blood or lung eosinophils in the two groups of mice exposed to A. fumigatus. These results indicate that lung injury in Aspergillus-antigen challenged animals may be the result of the eosinophil mediators and that IgE-mediated injury may not be significant in this model, which may be a significant variation between the model and human allergic aspergillosis.

Immunopathological response of C57BL/6 and C3H/HeN mice to Aspergillus fumigatus antigens

C3H/HeN and C57BL/6 mice were exposed to culture filtrate (CF) and mycelial extracts (ME) of Aspergillus fumigatus (Af) intranasally. Animals received 6, 8 or 10 biweekly doses and were sacrificed 2 weeks after the last dose was administered. Specific antibodies against Af were detected in their sera by biotin-avidin-linked immunosorbent assay (BALISA). Antibodies against Af belonging to all isotypes showed an increase in both strains of mice. A progressive increase in IgG and IgA antibody isotypes against both CF and ME antigens was detected in C3H/HeN mice during the entire experimental period, whereas most antibody levels peaked after the 8th dose and remained steady or decreased slightly in the C57BL/6 strain. Lung lavage studies showed a relative decrease in the number of macrophages and an increase in the number of lymphocytes after the 6th and 8th instillation of Af antigens in both strains of mice. Histology of the lung demonstrated a progressive inflammatory reaction in C57BL/6 mice during the experimental period. On the other hand, the C3H/HeN mice showed a negligible inflammatory pulmonary reaction. The antibody responses and inflammatory changes detected in the lungs of mice exposed to Af antigens are comparable to allergic bronchopulmonary aspergillosis (ABPA) in humans and hence this model will be of value in understanding the disease mechanism in ABPA and related diseases.