Modeling functional network topology following stroke through graph theory: functional reorganization and motor recovery prediction.

The study of functional reorganization following stroke has been steadily growing supported by advances in neuroimaging techniques, such as functional magnetic resonance imaging (fMRI). Concomitantly, graph theory has been increasingly employed in neuroscience to model the brain's functional connectivity (FC) and to investigate it in a variety of contexts. The aims of this study were: 1) to investigate the reorganization of network topology in the ipsilesional (IL) and contralesional (CL) hemispheres of stroke patients with (motor stroke group) and without (control stroke group) motor impairment, and 2) to predict motor recovery through the relationship between local topological variations of the functional network and increased motor function. We modeled the brain's FC as a graph using fMRI data, and we characterized its interactions with the following graph metrics: degree, clustering coefficient, characteristic path length, and betweenness centrality (BC). For both patient groups, BC yielded the largest variations between the two analyzed time points, especially in the motor stroke group. This group presented significant correlations (P<0.05) between average BC changes and the improvements in upper-extremity Fugl-Meyer (UE-FM) scores at the primary sensorimotor cortex and the supplementary motor area for the CL hemisphere. These regions participate in processes related to the selection, planning, and execution of movement. Generally, higher increases in average BC over these areas were related to larger improvements in UE-FM assessment. Although the sample was small, these results suggest the possibility of using BC as an indication of brain plasticity mechanisms following stroke.

Modeling functional network topology following stroke through graph theory: functional reorganization and motor recovery prediction

The study of functional reorganization following stroke has been steadily growing supported by advances in neuroimaging techniques, such as functional magnetic resonance imaging (fMRI). Concomitantly, graph theory has been increasingly employed in neuroscience to model the brain's functional connectivity (FC) and to investigate it in a variety of contexts. The aims of this study were: 1) to investigate the reorganization of network topology in the ipsilesional (IL) and contralesional (CL) hemispheres of stroke patients with (motor stroke group) and without (control stroke group) motor impairment, and 2) to predict motor recovery through the relationship between local topological variations of the functional network and increased motor function. We modeled the brain's FC as a graph using fMRI data, and we characterized its interactions with the following graph metrics: degree, clustering coefficient, characteristic path length, and betweenness centrality (BC). For both patient groups, BC yielded the largest variations between the two analyzed time points, especially in the motor stroke group. This group presented significant correlations (P<0.05) between average BC changes and the improvements in upper-extremity Fugl-Meyer (UE-FM) scores at the primary sensorimotor cortex and the supplementary motor area for the CL hemisphere. These regions participate in processes related to the selection, planning, and execution of movement. Generally, higher increases in average BC over these areas were related to larger improvements in UE-FM assessment. Although the sample was small, these results suggest the possibility of using BC as an indication of brain plasticity mechanisms following stroke.

Fermented or unfermented milk using Bifidobacterium animalis subsp. lactis HN019: Technological approach determines the probiotic modulation of mucosal cellular immunity.

Functional foods are important sources of probiotic delivery, mainly by fermented milk products. The physiological benefits attributed to bifido bacteria are their abilities to interfere with the adhesion of pathogenic species to surfaces of intestinal cells, and to enhance the host's immune function through their metabolic activities. However, the effects of a technological approach - fermentation or addition of probiotic in milk, and its efficacy in health are rarely taken into consideration. Hence, fermented or unfermented milk using Bifidobacterium animalis subsp. lactis HN019 were administered to BALB/c mice for 14days. After that, the architecture of the gut was histologically investigated, and the related immune cells were examined by flow cytometry and immunofluorescence. Increase in mucus and cellularity production, changes in immune pattern and preservation of mucosal epithelia in health BALB/c mice were observed only in the fermented milk group. This suggested that changes in functionality of bifidobacteria and/or the metabolites produced by the fermentation process are the keys to improving beneficial effects in the host of the gut mucosa.

Prophylactic and therapeutic vaccination using dendritic cells primed with peptide 10 derived from the 43-kilodalton glycoprotein of Paracoccidioides brasiliensis.

Vaccination with peptide 10 (P10), derived from the Paracoccidioides brasiliensis glycoprotein 43 (gp43), induces a Th1 response that protects mice in an intratracheal P. brasiliensis infection model. Combining P10 with complete Freund's adjuvant (CFA) or other adjuvants further increases the peptide's antifungal effect. Since dendritic cells (DCs) are up to 1,000-fold more efficient at activating T cells than CFA, we examined the impact of P10-primed bone-marrow-derived DC vaccination in mice. Splenocytes from mice immunized with P10 were stimulated in vitro with P10 or P10-primed DCs. T cell proliferation was significantly increased in the presence of P10-primed DCs compared to the peptide. The protective efficacy of P10-primed DCs was studied in an intratracheal P. brasiliensis model in BALB/c mice. Administration of P10-primed DCs prior to (via subcutaneous vaccination) or weeks after (via either subcutaneous or intravenous injection) P. brasiliensis infection decreased pulmonary damage and significantly reduced fungal burdens. The protective response mediated by the injection of primed DCs was characterized mainly by an increased production of gamma interferon (IFN-γ) and interleukin 12 (IL-12) and a reduction in IL-10 and IL-4 compared to those of infected mice that received saline or unprimed DCs. Hence, our data demonstrate the potential of P10-primed DCs as a vaccine capable of both the rapid protection against the development of serious paracoccidioidomycosis or the treatment of established P. brasiliensis disease.

SEM and neurohistological observations of nerve endings in the middle region of the tongue of the collared peccary (Tayassu tajacu): a silver impregnation method.

The presence of lingual papillae and the nerve endings in the middle region of the tongue mucosa of collared peccary (Tayassu tajacu) were studied using scanning electron microscopy and light microscopy, based upon the silver impregnation method. The middle region of tongue mucosa revealed numerous filiform and fungiform papillae. The thick epithelial layer showed epithelial cells and a dense connective tissue layer containing nerve fibre bundles and capillaries. The sensory nerve endings, intensely stained by silver impregnation, were usually non-encapsulated and extended into the connective tissue of the filiform and fungiform papillae very close to the epithelial cells. In some regions, the sensory nerves fibres formed a dense and complex network of fine fibrils. The presence of these nerve fibrils may characterize the mechanisms of transmission of sensitive impulses to the tongue mucosa.

Distribution of latent bovine herpesvirus 2 DNA in tissues of experimentally infected sheep.

The biology of latent infection by bovine herpesvirus 2 (BoHV-2), the agent of mammillitis in cows, remains largely unknown. We herein report attempts to reactivate the latent infection and investigated the sites of BoHV-2 latency in experimentally infected sheep. Ewes inoculated with BoHV-2 in the udder's skin shed virus for up to five days, developed mammillitis and seroconverted. However, attempts to reactivate latent infection by dexamethasone administration at day 40 pi failed. Nevertheless, viral DNA--and not infectious virus--was detected by PCR in several nerve ganglia and/or regional lymph nodes (LNs) of all animals at day 40 post-reactivation. Likewise, lambs previously inoculated with BoHV-2 in the nose harbored latent viral DNA in trigeminal ganglia, tonsils and regional LNs. These results demonstrate that BoHV-2 establishes latent infection in nerve ganglia and in regional lymphoid tissues, yet virus reactivation is not easily achieved by standard protocols used.

In vivo hydroquinone exposure impairs allergic lung inflammation in rats.

Hydroquinone (HQ) is naturally found in the diet, drugs, as an environmental contaminant and endogenously generated after benzene exposure. Considering that HQ alters the immune system and its several source of exposures in the environment, we hypothesized that prolonged exposure of HQ could affect the course of an immune-mediated inflammatory response. For this purpose, male Wistar rats were intraperitoneally exposed to vehicle or HQ once a day, for 22 days with a 2-day interval every 5 days. On day 10 after exposure with vehicle or HQ, animals were ovalbumin (OA)-sensitized and OA-aerosolized challenged on day 23. HQ exposure did not alter the number of circulating leukocytes but impaired allergic inflammation, evidenced by lower number of leukocytes in the bronchoalveolar lavage fluid 24h after OA-challenge. Reduced force contraction of ex vivo tracheal segments upon OA-challenge and impaired mesentery mast cell degranulation after in situ OA-challenge were also detected in tissues from HQ exposed animals. The OA-specificity on the decreased responses was corroborated by normal trachea contraction and mast cell degranulation in response to compound 48/80. In fact, lower levels of circulating OA-anaphylactic antibodies were found in HQ exposed rats, as assessed by passive cutaneous anaphylaxis assay. The reduced level of OA-anaphylactic antibody was not dependent on lower number or proliferation of lymphocytes. Nevertheless, lower expression of the co-stimulatory molecules CD6 and CD45R on OA-activated lymphocytes from HQ exposed rats indicate the interference of HQ exposure with signaling of the humoral response during allergic inflammation. Together, these data indicate specific effects of HQ exposure manifested during an immune host defense.

Acute and latent infection by bovine herpesvirus type 5 in experimentally infected goats.

The ability of alphaherpesviruses to infect different ruminant species may have important implications for control/eradication efforts. Serological data indicate that goats may be naturally infected with bovine herpesviruses. To investigate the susceptibility of goats to bovine herpesvirus-5 (BoHV-5), 3-4-month-old kids were inoculated intranasally with each of three Brazilian BoHV-5 isolates (G1, n=8; G2, n=5; G3, n=5). The acute infection was characterized by virus shedding in nasal secretions for up to 14 days (titers up to 10(5.97)TCID(50)/mL), mild respiratory signs and conjunctivitis. All animals seroconverted to BoHV-5, developing virus neutralizing (VN) titers from 4 to 32 to the homologous viruses. At day 60 post inoculation (pi), two animals from each group were euthanized for tissue collection and the remaining goats were submitted to dexamethasone administration (0.4 mg kg(-1) for 5 days). Dexamethasone treatment resulted in virus reactivation in 9 out of 12 animals, as ascertained by virus shedding and/or by increase in VN titers. Virus shedding was detected in 8/12 animals and lasted from 1 to 9 days. Latent viral DNA was detected by PCR in the olfactory bulb and/or trigeminal ganglia of 6/6 goats euthanized at day 60 pi and in 12/12 animals euthanized 40 days post-dexamethasone. These results show that young goats are susceptible to BoHV-5 and may shed virus upon reactivation of latent infection. Thus, it is reasonable to expect that goats raised in close contact with cattle in areas where BoHV-5 is endemic may be infected and therefore should be considered potential reservoirs of the virus.

Absence of CD4+ T cells impairs host defence of mice infected with Fonsecaea pedrosoi.

Chromoblastomycosis is a human chronic, often debilitating, suppurative, granulomatus mycosis of the skin and subcutaneous tissues beginning after inoculation trauma. It occurs worldwide, but is more frequently observed in tropical countries such as Brazil. Some studies have focused on fungus-host interaction, showing a predominantly cell-mediated immune response, with the activation of macrophages involved in fungus phagocytosis. Immunization with live conidia produced a high influx of CD4 T cells into the draining lymph node. The sensitized T cells proliferate in vitro when restimulated with specific antigen and preferentially produce IFN- gamma. To better characterize the role played by T cells on the chromoblastomycosis infection we used mice deficient for CD4 and CD8. Data determined by CFU counts associated with decreased DTH and IFN-gamma production of infected mice clearly demonstrated that, during experimental F. pedrosoi infection, absence of CD4(+) cells induces a more severe disease.

Phagocytosis, production of nitric oxide and pro-inflammatory cytokines by macrophages in the presence of dematiaceous [correction of dematiaceus] fungi that cause chromoblastomycosis.

Chromoblastomycosis is characterized by the slow development of polymorphic skin lesions (nodules, verrucas, tumores, plaques and scar tissue). Inside the host, infectious propagules adhere to epithelial cells and differentiate into sclerotic forms, which effectively resist destruction by host effector cells and allow onset of chronic disease. A cellular immune response against fungi is essential to control infection. Amongst the cells of the immune system, macrophages play the most important role in controlling fungal growth. In this study, we show that the fungicidal characteristic of macrophages is dependent on the fungal species that causes chromoblastomycosis. We began by observing that the phagocytic index was higher for Fonsecaea pedrosoi and Rhinocladiella aquaspersa compared with that of other fungi. Complement-mediated phagocytosis was more important for Phialophora verrucosa and R. aquaspersa and was inhibited by mannan when F. pedrosoi and R. aquaspersa conidia were phagocytosed by macrophages. We showed that macrophages killed significantly only R. aquaspersa. We also found that the phagocytosis of fungi has functional consequences for macrophages as phagocytosis resulted in down-modulation of MHC-II and CD80 expression as well as in the inhibition of the basal liberation of NO. However, the inhibition of the basal liberation of NO nor the down-modulation of MHC and co-stimulatory molecules were observed in the presence of R. aquaspersa.

Stimulation, inhibition and death of macrophages infected with Trichophyton rubrum.

Trichophyton rubrum is the most common pathogen causing dermatophytosis, accounting for approximately 80% of the reported cases of onychomycosis. Since 90% of the chronic dermatophyte infections are caused by T. rubrum, it is likely that this pathogen must have evolved mechanisms that evade or suppress cell-mediated immunity. Several reports have highlighted the participation of phagocytes in the immune defense against fungi; however, few studies have addressed the role of these cells in dermatophytosis. In this study, we investigated the interactions of resident and peritoneal macrophages with T. rubrum. We show here that the interaction of T. rubrum conidia with resident macrophages results in the production of TNF-alpha and IL-10 but not IL-12 and nitric oxide. Infected macrophages down-regulated the expression of co-stimulatory molecules (CD80 and CD54). We also show that phagocytosis of T. rubrum conidia is inhibited by the addition of fungal exoantigens or mannan. Cytotoxicity assays indicated that after 8 h of conidia ingestion macrophage viability decreased drastically. Electron microscopy revealed that the ingested conidia grow and differentiate into hyphae inside macrophages leading to rupture of the macrophage membrane.

Adjuvant effect of synthetic oligodeoxyribonucleotides (CpG-ODN) from the Paracoccidioides brasiliensis gp43 gene on the Th2-Th1 immunomodulation of experimental paracoccidioidomycosis.

Paracoccidioidomycosis (PCM) is caused by the dimorphic fungus Paracoccidioides brasiliensis. Immunostimulatory effects of P. brasiliensis DNA and CpG-oligodeoxyribonucleotides (CpG-ODN) have shown a Th2-Th1 immunomodulation of the isogenic murine model of susceptibility, which develops a progressive and disseminating disease. In this study, we investigated the optimum time interval and doses of CpG-ODN which are able to induce Th2-Th1 immunomodulation. The optimum concentrations for the induction of a decrease in antibody production were 0.5 and 1 microg. Mice immunized twice with CpG-ODN and gp43 (5 and 7 days before the challenge) showed a 60% higher chance of survival compared with the control group (nonimmunized), and an increase in Th1 isotype (IgG2a) was also observed. In vitro assays of naive and preimmunized mice showed discrete cellular proliferation when stimulated by suitable concentrations of CpG-ODN. Type 1 cytokines interleukin-12 (IL-12) and interferon-gamma were increased in cell culture supernatants, but no significant difference was found in Th2 IL-4 cytokines in stimulated or nonstimulated cell cultures. Concerning the Th2-Th1 kinetics in experimental PCM models by adjuvant effect of CpG-ODN, there are still many questions to be answered and clarified. However, the gathering of data obtained in this investigation has led us to suggest that the modulation of Th2-Th1 in experimental PCM depends on time and CpG-ODN concentration.

B and T cell responses elicited by monoclonal anti-idiotypic antibody (Ab2beta) mimicking gp43 from Paracoccidioides brasiliensis.

Paracoccidioidomycosis is a systemic mycosis endemic in Latin America, with a high prevalence in Brazil, Argentina, Colombia and Venezuela. The aetiological agent of disease is the thermal dimorphic fungus, Paracoccidioides brasiliensis. A glycoprotein of 43 kD (gp43) is the major antigen of P. brasiliensis. Antibodies directed to this antigen are detected in the sera of all patients with paracoccidioidomycosis (PCM). Recently, it has been shown that mice immunized with anti-gp43 monoclonal antibodies (MAbs) (Ab1), induce the idiotypic cascade in the gp43 system, which produced both, anti-Id antibodies (Ab2) and anti-anti-Id antibodies (Ab3). To further characterize the idiotypic cascade modulation in mice immunized with anti-gp43 MAb 17c, hybridomas were produced. Ab2 MAbs named 7.B12 inhibited (>95%) the binding of gp43 to MAb 17c (Ab1), suggesting that this anti-Id MAb bind to the idiotope, thus fulfilling the internal image criteria. To elucidate whether Ab2 MAb could act as antigen in serological assays, instead of gp43, sera from PCM patients were tested. Using an ELISA test, it was observed that antibodies from patients and not normal serum bound to Ab2. However, the ELISA test using Ab2 bound to the solid phase made possible to serologically monitor the patients after antifungal therapy, showing an equivalent curve when compared with ELISA test employing purified gp43. Our results also showed that, when mice were immunized with Ab2beta and their cells were exposed to gp43 in vitro, a T cell proliferation response was observed.

Regulation of T helper cell differentiation in vivo by GP43 from Paracoccidioides brasiliensis provided by different antigen-presenting cells.

Paracoccidioidomycosis, endemic in Latin America, is a progressive systemic mycosis caused by Paracoccidioides brasiliensis. The infection can evolve into different clinical forms that are associated with various degrees of suppressed cell-mediated immunity. Assuming that the effector immune response is a consequence of the preferential activation of either Th1 or Th2 subsets, in the present work we evaluated whether the nature of antigen-presenting cells (APCs) can influence the Th1/Th2 balance in vivo. It was observed that the injection of mature dendritic cells (DCs), macrophages and B cells primed the mice and induced a proliferation of T cells in vitro. It was seen that DCs from resistant mice stimulated predominantly interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), whereas macrophages activated IL-10, IL-4 and IFN-gamma-secreting T cells and B cells IL-4 and IL-10 only. Results presented here clearly demonstrate that DC drives the development of cells secreting Th1-derived cytokines, whereas B cells induce the differentiation of a Th2 phenotype in vivo.

Iatrogenic bile duct injuries.

BACKGROUND: The real incidence of bile duct injury (BDI) during laparoscopic cholecystectomy (LC) is not known. METHODS: Using questionnaires, we analyzed 91,232 LC performed by 170 surgical units in Brazil between 1990 and 1997. RESULTS: A total of 167 BDI occurred (0.18%); the most frequent were Bismuth type 1 injuries (67.7%). Most injuries (56.8%) occurred at the hands of surgeons who had surpassed the learning curve (50 operations). However, the incidence dropped with increasing experience; it was 0.77% at surgical departments with <50 operations vs 0.16% at departments with >500 operations. The diagnosis was made intraoperatively in 67.7%, but it was based on intraoperative cholangiography in only 19.5%. The procedure was converted to open surgery in 85.8% when the diagnosis of injury occurred intraoperatively, and laparotomy was performed in 90.7% when the injury was diagnosed postoperatively. The mean hospitalization time was 7.6 +/- 5.9 days, the major complications were stenosis and fistulas, and the mortality rate was 4.2%. CONCLUSION: The incidence of BDI after LC is similar to that reported for the open procedure. BDI increases mortality and morbidity and prolongs hospitalization; therefore, all efforts should be made to reduce its incidence.

Immunostimulatory DNA from Paracoccidioides brasiliensis acts as T-helper 1 promoter in susceptible mice.

Th1 immune responses afford protection against some pathogens like the fungus P. brasiliensis (P.b.), etiological agent of Paracoccidioidomycosis (PCM). It is well known that nonmethylated CpG sequences from bacterial DNA have immunomodulatory properties and can be used as a Th1-promoting adjuvant. By analyzing the available gene sequences of P.b. we observed a high number of unmethylated CpG dinucleotides. In a murine model of the PCM infection, the isogenic mouse strain known to be susceptible presents a predominant Th2 pattern. In order to access the possibility of the genomic DNA to act as a Th1-promoting adjuvant, in vitro assays were made and indicated a significant increase in phagocytosis when the macrophages were stimulated with DNA from P.b. and in vivo assays of a decreased production of antibodies antigp43, the main antigen of the PCM system. The analysis of the antibody isotypes and the cytokine production suggested a Th1 modulation in the susceptible animals. Thus, when mice were infected with fungus plus synthetic oligodeoxynucleotide (ODN), made from the available sequence of gp43, a decrease in the fungus dissemination was observed. Results herein described suggest that genomic DNA from P.b. could have a immunostimulatory function as a Th-1-promoting adjuvant in susceptible mice.

Mouse B-1 cell-derived mononuclear phagocyte, a novel cellular component of acute non-specific inflammatory exudate.

At least three B cell subsets, B-1a, B-1b and B-2, or conventional B cells are present in the mouse periphery. Here we demonstrate that B-1 cells spontaneously proliferate in stationary cultures of normal adherent mouse peritoneal cells. B-1 cells were characterized by morphology, immunohistochemistry and flow cytometry. IgM was detected in the supernatants of these cultures. We demonstrated that the major cell population analyzed expresses the B-1b phenotype. When these cells were transferred to a new culture, a large proportion of them adhere to the plastic surface, and spread as bipolar cells endowed with the capacity to phagocytose via Fc and mannose receptors. Flow cytometry analysis of these adherent cells demonstrated that the great majority of them share both B-220 and Mac-1 antigens. Nevertheless, 45% of them were exclusively Mac-1(+). Finally, when they were labeled in vitro with [(3)H]thymidine and transferred to the peritoneal cavity of naive mice, they migrate to a non-specific inflammatory focus induced by a foreign-body implant. These data demonstrate that B-1 cells, mainly B-1b cells, not only proliferate and differentiate into a mononuclear phagocyte in vitro, but also that they exit the peritoneal cavity and migrate to a non-specific inflammatory milieu.

The low efficiency of dendritic cells and macrophages from mice susceptible to Paracoccidioides brasiliensis in inducing a Th1 response.

In the present study we evaluated T cell proliferation and Th lymphokine patterns in response to gp43 from Paracoccidioides brasiliensis presented by isolated dendritic cells from susceptible and resistant mice. T cell proliferation assays showed that dendritic cells from susceptible mice were less efficient than those from resistant mice. The pattern of T cell lymphokines stimulated by dendritic cells was always Th1, although the levels of IL-2 and IFN-gamma were lower in T cell cultures from susceptible mice. To determine whether different antigen-presenting cells such as macrophages and dendritic cells stimulated different concentrations of Th1 lymphokines, the production of IFN-gamma and IL-2 was measured. It was observed that dendritic cells were more efficient than macrophages in stimulating lymphoproliferation in resistant mice. However, no significant difference was observed for IFN-gamma or IL-2 production. When cells from susceptible mice were used, macrophages were more efficient in stimulating lymphoproliferation than dendritic cells, but no difference was observed in the production of Th1 cytokine. Taken together, these results suggest the lower efficiency of dendritic cells and macrophages from B10.A mice in stimulating T cells that secrete Th1 lymphokines in vitro, an effect that may be involved in the progression of the disease in vivo.

The low efficiency of dendritic cells and macrophages from mice susceptible to Paracoccidioides brasiliensis in inducing a Th1 response

In the present study we evaluated T cell proliferation and Th lymphokine patterns in response to gp43 from Paracoccidioides brasiliensis presented by isolated dendritic cells from susceptible and resistant mice. T cell proliferation assays showed that dendritic cells from susceptible mice were less efficient than those from resistant mice. The pattern of T cell lymphokines stimulated by dendritic cells was always Th1, although the levels of IL-2 and IFN-gamma were lower in T cell cultures from susceptible mice. To determie whether different antigen-presenting cells such as macrophages and dendritic cells stimulated different concentrations of Th1 lymphokines, the production of IFN-gamma and IL-2 was measured. It was observed that dendritic cells were more efficient than macrophages in stimulating lymphoproliferation in resistant mice. However, no significant difference was observed for IFN-gamma or IL-2 production. When cells from susceptible mice were used, macrophages were more efficient in stimulating lymphoproliferation than dendritic cells, but no difference was observed in the production of Th1 cytokine. Taken together, these results suggest the lower efficiency of dendritic cells and macrophages from B10.A mice in stimulating T cells that secrete Th1 lymphokines in vitro, an effect that may be involved in the progression of the disease in vivo

Subcutaneous infection of mice with Paracoccidiodes brasiliensis induces a peculiar pattern of inflammatory and immune responses.

It is well established that resistance or susceptibility to Paracoccidioidis brasiliensis infection in mice is under strict host's genetic control. Mice from A/Sn strain inoculated by the ip route are resistant to fungal infection while infection induced in mice from B10.A strain results in a fatal disease. The early cellular events of infection in both strains are characterized by a marked neutrophilic infiltration that is more prominent in B10.A mice. A peculiar characteristic of the Paracoccidioides brasiliensis-mouse model is that the subcutaneous (sc) inoculations of the fungus either in resistant (A/Sn) or susceptible (B10.A) mice is self-curing and tums mice from the B10.A strain able to express typical DTH reaction to fungal antigens, as observed in A/Sn mice. Here we report the investigation on the early events of the inflammatory response induced by the inoculation of live fungus into the hind footpad of A/Sn (resistant) and B10.A (susceptible) mice. The influence of neutrophils on the inflammatory response and antibody titers or DTH response to gp43, the major fungal antigen, was also evaluated. Results showed a different course of the inflammatory response induced by fungal inoculation in A/Sn and B10.A mice. Neutrophil depletion before infection differently influenced the kinetics of the inflammatory process in both mice strains but did not modify the fungal load in the lesions. In neutrophil depleted mice from both strains, a decrease in DTH response and an increase in total antibody titers to gp43 were observed. The significant increase in the fungal load in lesions seen in nude mice indicates that the self-limited infection evoked by fungal inoculation into the subcutaneous tissue is a T-cell dependent phenomenon. The implications of these observations in the pathogenesis of paracoccidioidomycosis are discussed.