A and A/J mice infected with Pb, mainly at the later phase of infection with Pb18. Tissue necrosis was also observed in association with fibrotic lesions, only in resistant mice infected with Pb18 and in both mouse strains infected with Pb265, see more leading to resolution of the infection. In this study, lymphomononuclear cells showed intense IFN-γ staining, distributed at the periphery of necrotic lesions
of resistant mice. Some authors have described the role of osteopontin (OPN) in the preferential activation of cellular immunity, increasing the cytokine expression of IL-12 and inhibiting IL-10, thus, leading to the immune response toward Th1 immune pattern, which is important to resistance for infection (Ashkar et al., 2000). Li
et al. (2003) demonstrated that IFN-γ stimulates the OPN expression, which in turn increases the IFN-γ production, suggesting a mechanism of positive regulation to development of Th1 immune response. Increased OPN expression, particularly observed in macrophages, was detected in the granulomatous lesions of mice, as previously described (Nishikaku et al., 2008). Although B10.A mice have shown increased cellular positivity of OPN and IFN-γ at the later stage of infection with Pb18, no association with the control of the infection was found. Decreased OPN immunostaining was detected in Pb265-infected mice in comparison with Pb18-infected mice. Furthermore, OPN reactivity decreased Temozolomide ic50 throughout the infection with Pb265, as observed for IFN-γ, probably due to resolution of the infection. Hence, presence of OPN and IFN-γ at paracoccidioidal granulomas suggests that both these components might be part of mechanisms to control the P. brasiliensis infection, particularly in resistant mice. Altogether, our data suggest the active participation Hydroxychloroquine price of IFN-γ, TNF-α, TGF-β, OPN, and of immune cell populations (macrophage, giant cells, and lymphocytes) in the tissue alterations observed during the development of granulomatous response and also in the immune effector
mechanisms against P. brasiliensis infection. This study characterized the presence of IFN-γ in lymphomononuclear cells indicating its participation in the tissue response developed during the experimental infection with P. brasiliensis. The findings suggest that intense expression of IFN-γ in lymphomononuclear cells of susceptible and resistant mice infected with the highly virulent Pb18, points toward a similar activation of cellular immune response in the early phase of the infection in these animals and to an absence of correlation between resistance and genetic background of the host at this time point of infection; however, the expressive increase of IFN-γ positive cells in resistant mice at the later time point, suggests that at this stage, this mouse strain has a more efficient capacity to activate phagocytes, mainly macrophages, to control the fungal dissemination.