Aspergillus antigen-induced eosinophil differentiation in a murine model

Abstract

Eosinophilia is a prominent feature of the cellular response in allergic and parasitic diseases. Allergic bronchopulmonary aspergillosis due to colonization of the lungs of some asthmatics with Aspergillusfumigatus is characterized by high levels of serum immunoglobulin E and peripheral blood (PB) and lung eosinophilia. This study investigates the role of eosinophils in the pathogenesis of allergic bronchopulmonary aspergillosis by using a mouse model. BALB/c mice were immunized intranasally and intraperitoneally with A. fumigatus antigens (Ag), and the eosinophils in PB and bone marrow (BM) were enumerated. Eosinophilopoiesis in BM cultures was studied in the presence of murine recombinant interleukin-5 (mrIL-5) and supernatants from pokeweed mitogen-stimulated spleen cells as the source of eosinophil differentiation factors. Eosinophils were quantitated by direct counting and by estimating eosinophil peroxidase activity. The results indicate that the percentage of eosinophils in the PB (5.77 ± 1.17) and the BM (11.19 + 4.31) of mice exposed to A. fumigatus Ag was higher than in controls (PB, 2.42 ± 0.76; BM, 5.12 + 2.79; P < 0.01 for both). Similarly, a significant increase in eosinophils was observed in the BM population from mice exposed to A. fumigatus Ag compared with that in controls when cultured with murine recombinant interleukin-5 (23.13 + 7.14 versus 13.77 ± 5.79, P < 0.01), indicating that the mice exposed to A. fumigatus Ag had significantly greater numbers of eosinophil precursors in their BM. This study demonstrates that A. fumigatus Ag may be involved in the in vivo commitment of stem cells in the eosinophil differentiation pathway.

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

“…Blood eosinophils were counted after the last exposure to Af antigen. Peripheral blood was collected from the tail vein in tubes containing heparin (25 U/ml) and stained with Discombe's fluid (5 mg eosin Y dissolved in 1 ml acetone and further diluted to 20 ml with distilled water), as previously described (1,2). Tlie stained eosinophils were then counted with a hemacytometer.…”

“…Eosinophil peroxidase was studied as a measure of eosinophil activity and was estimated in bonemarrow cells, as previously described (2,3,9). Briefly, 100 )il of bone-marrow cells (5xlO''/ml) from mice was cultured in complete RPMI 1640 medium in 96-well, sterile, round-bottom plates.…”

“…In previous studies, we have demonstrated that the Aspergillus fumigatus (Af) antigen invokes characteristic features of allergic aspergillosis in mice. These include elevated serum IgE level, Af-specific serum antibodies, and peripheral blood and lung eosinophiha (1)(2)(3)(4). Tliese manifestations are a result of activation of CD4-I-T-helper 2 (Tl:2) cells by Aspergillus antigens, lnterleukin-4 (IL-4), a major cytokine produced by Th2 cells, is responsible for both IgE antibody isotype switching and enhanced igGl production in primed mice (5,6).…”

Eosinophil degranulation: an evolutionary vestige or a universally destructive effector function?

“…Specifically, only in a limited number of circumstances (e.g. responses to helminth parasites [8] or some fungal pathogens [9]) does degranulation appear to be a dominant effector function. A more expansive hypothesis suggesting that degranulation is a widely used and singularly important effector function whose ability to kill conveys an evolutionarily selective advantage to the host is problematic.…”

Role of prostaglandin D2/CRTH2 pathway on asthma exacerbation induced by Aspergillus fumigatus

“…[38][39][40][41] Exposure to A. fumigatus extracts leads to eosinopoiesis and the subsequent increase in peripheral blood eosinophils, reiterating that fungal antigens are responsible for the recruitment of eosinophils into the affected tissues. 42 In our previous studies we showed that prolonged exposure of OVA-sensitized and OVA-challenged rats to A. fumigatus spores resulted in enhanced levels of serum IgE, pulmonary eosinophils and bronchial hyper-responsiveness. 14,43 Although some authors reported accumulation of eosinophils following A. fumigatus inhalation, [44][45][46][47] in this study only a few eosinophils were observed after A. fumigatus exposure alone.…”