RESUMEN
The secretion of interferon-gamma (IFN-gamma), interleukin-2 (IL-2), IL-4, IL-5, and IL-10 by antigen-stimulated lymph node cells, eosinophil maturation, and the antibody isotypes produced were examined during intraperitoneal infection of susceptible (B10.A) and resistant (A/Sn) mice with Paracoccidioides brasiliensis. Lymph node cells from resistant mice produced early and sustained levels of IFN-gamma and IL-2, whereas susceptible animals secreted low to undetectable amounts of these type 1 cytokines. Both mouse strains presented late and transient production of IL-4, whereas IL-10 was produced constantly throughout the course of disease. Resistant animals produced increasing levels of IL-5 in the chronic phase of the infection (from the eighth week on), whereas susceptible mice showed two peaks of IL-5 production, at the first and twelfth weeks after infection. Only the susceptible strain presented medullary and splenic eosinophilia concomitant with the raised IL-5 production. In resistant mice, the levels of IgG2a antibodies were significantly higher than those observed in susceptible mice, which preferentially secreted IgG2b and IgA isotypes. Taken together, these results demonstrate that a sustained production of IFN-gamma and IL-2 and a predominant secretion of IgG2a antibodies are associated with resistance to P. brasiliensis. In contrast, the production of low levels of IFN-gamma, early secretion of high levels of IL-5 and IL-10, eosinophilia, and a preferential secretion of IgG2b and IgA isotypes characterize the progressive disease in susceptible animals.
Asunto(s)
Interferón gamma/deficiencia , Interleucinas/biosíntesis , Paracoccidioides , Paracoccidioidomicosis/inmunología , Células TH1/inmunología , Animales , Anticuerpos Antifúngicos/biosíntesis , Linfocitos B/inmunología , Médula Ósea/patología , Eosinofilia/etiología , Eosinofilia/inmunología , Femenino , Predisposición Genética a la Enfermedad , Inmunidad Celular , Inmunidad Innata , Inmunoglobulina A/biosíntesis , Inmunoglobulina G/biosíntesis , Interferón gamma/biosíntesis , Interferón gamma/genética , Interleucina-2/biosíntesis , Interleucina-2/genética , Interleucina-5/biosíntesis , Interleucina-5/genética , Interleucinas/genética , Interleucinas/metabolismo , Ganglios Linfáticos/inmunología , Activación de Linfocitos , Activación de Macrófagos , Ratones , Ratones Endogámicos A , Paracoccidioidomicosis/genética , Paracoccidioidomicosis/patología , Cavidad Peritoneal/citología , Bazo/patología , Células TH1/metabolismo , Células Th2/inmunologíaRESUMEN
The effect of macrophage blockade on the natural resistance and on the adaptative immune response of susceptible (B10.D2/oSn) and resistant (A/Sn) mice to Paracoccidioides brasiliensis infection was investigated. B10.D2/oSn and A/Sn mice previously injected with colloidal carbon were infected ip with yeast cells to determine the 50% lethal dose, and to evaluate the anatomy and histopathology, macrophage activation, antibody production and DTH reactions. Macrophage blockade rendered both resistant and susceptible mice considerably more susceptible to infection, as evidenced by increased mortality and many disseminated lesions. P. brasiliensis infection and/or carbon treatment increased the ability of macrophages from resistant mice to spread up to 25 days after treatment. In susceptible mice the enhanced spreading capacity induced by carbon treatment was impaired at all assayed periods except at 1 week after infection. Macrophage blockade enhanced DTH reactions in resistant mice, but did not alter these reactions in susceptible mice, which remained anergic. To the contrary, macrophage blockade enhanced specific antibody production by susceptible mice, but did not affect the low levels produced by resistant mice. The effect of macrophage blockade confirms the natural tendency of resistant animals to mount DTH reactions in the course of the disease and the preferential antibody response developed by susceptible mice after P. brasiliensis infection. On the whole, macrophage functions appear to play a fundamental role in the natural and acquired resistance mechanisms to P. brasiliensis infection.
Asunto(s)
Macrófagos Peritoneales/inmunología , Paracoccidioidomicosis/inmunología , Animales , Anticuerpos Antifúngicos/sangre , Carbono/farmacología , Movimiento Celular/efectos de los fármacos , Coloides/farmacología , Susceptibilidad a Enfermedades , Femenino , Hipersensibilidad Tardía , Inmunidad Innata , Inmunoglobulina G/sangre , Dosificación Letal Mediana , Activación de Macrófagos , Ratones , Ratones Endogámicos , Paracoccidioides/inmunología , Paracoccidioides/patogenicidad , Paracoccidioidomicosis/patologíaRESUMEN
Paracoccidioidomycosis patients show hyperactive humoral immune responses. Consequently, we investigated whether cytokines in supernatants from Paracoccidioides brasiliensis-stimulated gamma/delta T cells support B-cell activation. We detected proliferation of B cells and increased immunoglobulin M (IgM) and IgG production. Thus, gamma/delta T cells may participate in polyclonal B-cell activation during paracoccidioidomycosis.
Asunto(s)
Linfocitos B/inmunología , Paracoccidioides/inmunología , Subgrupos de Linfocitos T/inmunología , Anticuerpos Antifúngicos/biosíntesis , Formación de Anticuerpos , Antígenos Fúngicos/inmunología , Humanos , Activación de Linfocitos , Receptores de Antígenos de Linfocitos T gamma-delta/inmunologíaRESUMEN
Paracoccidioides brasiliensis, a dimorphic fungus, causes chronic granulomatous mycosis in susceptible individuals. Different reports have shown that cell-mediated immunity is essential for protection against systemic mycosis, including paracoccidioidomycosis. We analyzed the reactivity of alpha beta and gamma delta T cells from unexposed Caucasian donors to P. brasiliensis yeast form components. Our results indicate: (i) alpha beta and gamma delta T cells proliferate after in vitro stimulation with lysates of P. brasiliensis; (ii) similar numbers of alpha beta T cells (f = 1/21,000) and of gamma delta T cells (f = 1/8000) respond to P. brasiliensis; (iii) P. brasiliensis-reactive gamma delta T cells express the V gamma 9V delta 2 TCR; (iv) the stimulatory activity of P. brasiliensis for both alpha beta and gamma delta T cells primarily resides in a high molecular weight (100 kDa) and in a low molecular weight (< 1 kDa) fraction; (v) the ligands responsible for stimulation of both alpha beta and gamma delta T cells are sensitive to proteinase treatment. We conclude that both alpha beta and gamma delta T cells from healthy individuals respond to ubiquitous protein antigens of P. brasiliensis.
Asunto(s)
Antígenos Fúngicos/inmunología , Paracoccidioides/inmunología , Receptores de Antígenos de Linfocitos T alfa-beta/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Subgrupos de Linfocitos T/inmunología , Presentación de Antígeno/inmunología , Endopeptidasa K , Citometría de Flujo , Humanos , Interleucina-2/biosíntesis , Activación de Linfocitos , Serina EndopeptidasasRESUMEN
The specific delayed-type hypersensitivity (DTH) response was evaluated in resistant (A/SN) and susceptible (B10.A) mice intraperitoneally infected with yeasts from a virulent (Pb18) or from a non-virulent (Pb265) Paracoccidioides brasiliensis isolates. Both strains of mice were footpad challenged with homologous antigens. Pb18 infected A/SN mice developed an evident and persistent DTH response late in the course of the disease (90th day on) whereas B10.A animals mounted a discrete and ephemeral DTH response at the 14th day post-infection. A/SN mice infected with Pb265 developed cellular immune responses whereas B10.A mice were almost always anergic. Histological analysis of the footpads of infected mice at 48 hours after challenge showed a mixed infiltrate consisting of predominantly mononuclear cells. Previous infection of resistant and susceptible mice with Pb18 did not alter their DTH responses against heterologous unrelated antigens (sheep red blood cells and dinitrofluorobenzene) indicating that the observed cellular anergy was antigen-specific. When fungal related antigens (candidin and histoplasmin) were tested in resistant mice, absence of cross-reactivity was noted. Thus, specific DTH responses against P. brasiliensis depend on both the host's genetically determined resistance and the virulence of the fungal isolate.
Asunto(s)
Hipersensibilidad Tardía , Paracoccidioidomicosis/inmunología , Animales , Antígenos Fúngicos , Reacciones Cruzadas , Modelos Animales de Enfermedad , Femenino , Ratones , Ratones Endogámicos A , Paracoccidioides/inmunología , Paracoccidioides/patogenicidad , Paracoccidioidomicosis/patología , Virulencia/inmunologíaRESUMEN
In a previous report it was shown that there are resistant, susceptible, and intermediate strains of mice to intraperitoneal Paracoccidioides brasiliensis infection. In the present work, we investigated the type of inheritance and the number of genes that determine resistance to paracoccidioidomycosis. Parental and hybrid mice were inoculated intraperitoneally with 5 X 10(6) P. brasiliensis yeast cells, and mortality was scored daily. Analysis of susceptible and resistant parental strains and of F1, F2, and backcross mice showed that the resistance to P. brasiliensis seems to be controlled genetically by a single dominant gene, which we designated the Pbr locus. The mean survival times of susceptible F2 and backcross hybrids were very similar to that of the susceptible parent. Examination of the pathological changes observed in parental and F1 mice, 6 months after infection, showed that F1 offspring presented a similar number and distribution of lesions to those of the resistant strains. The Pbr gene is not linked to H-2, Hc, and albino genes. Furthermore, resistance to paracoccidioidomycosis is controlled by an autosomal gene.
Asunto(s)
Hongos Mitospóricos/inmunología , Paracoccidioides/inmunología , Paracoccidioidomicosis/genética , Animales , Genes Dominantes , Ligamiento Genético , Inmunidad Innata , Ratones , Ratones Endogámicos/genética , Ratones Endogámicos/microbiología , Paracoccidioidomicosis/inmunología , Paracoccidioidomicosis/patologíaRESUMEN
The occurrence of a polysaccharide fraction of Paracoccidioides brasiliensis cell wall with toxic, granuloma-inducing and macrophage-stimulating activities was demonstrated. After fractionation of the lipid-extracted wall with 1 M-NaOH, three fractions were obtained: (1) an alkali-insoluble fraction; (2) an alkali-soluble, acid-insoluble fraction and (3) an alkali-soluble, acid-soluble fraction. When the three fractions were injected into mice only fraction (1) was able to induce chronic lung inflammation, causing a marked loss in body weight and death at a dose of 6 mg per animal. Analysis of the stimulation of peritoneal macrophages of mice (measured by cell spreading on glass) after intraperitoneal injection of fraction 1 showed that 75% of the cells were able to spread even 20 d after inoculation.