Immunolocalization of IFN-gamma in the lesions of resistant and susceptible mice to Paracoccidioides brasiliensis infection

Abstract

The important role of interferon-gamma (IFN-c) in protective immunity in mycosis is well established, except for its participation in fungal granulomas. Herein, we employ immunohistochemical reactions to describe the in situ localization of IFN-c in granulomas of susceptible (B10.A) and resistant (A/J) mice to infection with Paracoccidioides brasiliensis (Pb). After infection with the highly virulent Pb18, IFN-c-positive lymphomononuclear cells were localized mainly at the periphery of granulomas in both mouse strains. The numbers of positive cells found in compact granulomas of A/J mice increased significantly from 15 to 120 days postinfection. At this time, significantly more positive cells were detected in the compact granulomas of resistant mice than in the loose, multifocal lesions of the susceptible ones. In infection with the slightly virulent Pb265, the same pattern of IFN-c localization was found as in Pb18 infection, but there was decreased staining at 120 days due to the presence of only residual lesions in both mouse strains. The marked IFN-c staining observed in the granulomas of resistant mice at the later stage of Pb infection confirms its importance in fungal dissemination control, and suggests a contribution to the development of paracoccidioidal granuloma.

Progress Toward a Human Vaccine Against Coccidioidomycosis

“…Results of numerous studies suggest that the T helper 1 (Th1) subpopulation of CD4 + T cells plays a pivotal role in protection against coccidioidomycosis [43•, 66]. Production of IFN-γ by Th1 cells activates phagocytes to kill the fungal pathogen and contributes to the development of granulomas at sites of tissue insult [67], while loss of IL-12 or IFN-γ secretion increases the severity of fungal infections [68, 69]. …”

Cytokines Expressed in the Granulomatous Lesions in Experimental Paracoccidioidomycosis: Role in Host Protective Immunity and as Fungal Virulence Factor

“…In previous studies on the murine model of PCM developed by our group, IFN-γ-positive cells with lymphocyte morphology were localized mainly at the periphery of granulomas in both mouse strains; a significant increase in positive cells was found in compact granulomas of A/J mice at 120 days compared to 15 days post infection and a significantly higher number of positive cells was detected in compact granulomas of resistant mice than in loose and multifocal granulomas of susceptible at 120 days post infection [22]. Also, TNF-α (unpublished data) and TGF-β [21] immunostaining was detected in macrophages and multinucleated giant cells, as well as in extracellular matrix components.…”

“…Briefly, slides sections were deparaffinized and rehydrated, then incubated with hydrogen peroxide (30%) for 30 min at room temperature in a shaker, for blocking endogenous peroxidase. After that, blocking of nonspecific sites with normal serum/bovine serum albumin 10% (1:1 dilution) was carried out for 30 min at room temperature and followed by application of Tris-buffered saline (TBS) for blocking endogenous biotin in tissues for 2 h. Slides were incubated with adequate volume of rabbit pan-specific polyclonal antibody anti-TNF-α or anti-TGF-β (1/30) (R&D SYSTEMS, Inc., Minneapolis, MN, USA) and monoclonal antibody anti-IFN-γ (according to the protocol described previously by [20][21][22], overnight at 4°C, diluted in PBS/Tween 20 0.3%. After incubation with primary biotinylated anti-IgG antibody (1/1000) (Rockland, Gilbertsville, PA, USA) was applied on tissues for 1 h at room temperature, followed by incubation with streptavidin-peroxidase (1/50) (Vector Laboratories, Burlingame, CA, USA).…”

Problems of Vaccinal Prevention of Deep Mycoses

“…Иммунизация пептидом (р10), содер-жащим эпитоп иммунодоминантного специфиче-ского антигена (gp43), индуцировала протективный Th1-клеточный ответ у мышей, интратрахеально зараженных вирулентным штаммом P. brasiliensis [48]. Вакцина на основе гибридных флагеллинов серовара Dublin Salmonella enterica, генетически связанных с нуклеотидными последовательностя-ми p10 gp43, стимулировала преимущественно Th1-клеточный ответ и приводила к повышению протективности при заражении вакцинированных мышей [49].…”