1 The in¯ammatory cell in¯ux towards the peritoneal cavity in mice inoculated i.p. with live or dead Histoplasma capsulatum or with its subcellular preparations was studied. We also evaluated the e ects of dexamethasone (Dexa) or MK886, an inhibitor of leukotriene (LT) biosynthesis, on the recruitment of leukocytes. 2 Live yeast form of fungus (LYH) induced an increase in neutrophils (NE) which was highest 4 to 24 h after inoculation. Mononuclear cell (MN) migration beginning at 24 h with a gradual increase over 48 and 168 h, and an eosinophil (EO) recruitment occurs between 24 and 48 h. 3 NE and EO recruitment induced by dead mycelial form of fungus (DMH) was greater than that observed for dead yeast form of fungus (DYH). A similar leukocyte migration pattern was seen after i.p. injection of the alkali-insoluble fraction (F1) from DYH (F1Y) and F1 from DMH (F1M) this being more active than former. The di erence in concentration of b-glucan in DYH and DMH could explain the di erent in¯ammatory capacity exhibited by the two forms of H. capsulatum. 4 LT seems to be the principal mediator of leukocyte migration in response to LYH, DYH or DMH or to b-glucan. However, other mediators appear to contribute to NE and EO migration since the treatment with Dexa was more e ective in inhibiting cell migration than MK886.

Chemokines and chemokine receptors play a role in cell recruitment during granulomatous inflammatory reactions. Here, we evaluated the expression of chemokines and chemokine receptors and their regulation by IFN-gamma in the course of Paracoccidioides brasiliensis (Pb) infection in mice. We found an association between KC and MIP-1alpha (CCL3) production and neutrophil infiltration in the lungs of Pb-infected mice during the early acute phase of infection. High levels of RANTES/CCL5, MCP-1/CCL2, IP-10/CXCL10, and Mig/CXCL9 simultaneously with mononuclear cell infiltration in the lungs was found. In the absence of IFN-gamma (GKO mice) we observed increased production of KC and MIP-1alpha and chronic neutrophilia. Moreover, we found a change in the chemokine receptor profiles expressed by wild-type (WT) versus GKO animals. Increased expression of CXCR3 and CCR5, and low levels of CCR3 and CCR4 were observed in the lungs of Pb-infected WT mice, whereas the opposite effect was observed in the lungs of GKO mice. Consistent with these results, infected cells from WT mice preferentially migrated in response to IP-10 (CXCR3 ligand), while those from GKO mice migrated in response to eotaxin/CCL11 (CCR3 ligand). These results suggest that IFN-gamma modulates the expression of chemokines and chemokine receptors as well as the kind of cells that infiltrate the lungs of Pb-infected mice.

The difference in the susceptibility between microconidia and arthroconidia depends on the drug and on the strain, and may be one of the causes of therapeutic failure. Also, the level of resistance to the antibiotic hygromycin B presented by microconidia of these isolates will allow the use of hygromycin resistance as a dominant marker in fungal transformation procedures in future studies of gene function.

The immune events that take place in the central nervous system (CNS) during cryptococcal infection are incompletely understood. We used competitive reverse transcription-PCR to delineate the time course of the local expression of mRNAs encoding a variety of cytokines and inducible nitric oxide synthase (iNOS) during progressive murine cryptococcal meningoencephalitis and assessed the CNS inflammatory response using immunohistochemistry. Interleukin 18 (IL-18), transforming growth factor ␤1, and IL-12p 40 mRNAs were constitutively expressed in the brains of infected and uninfected mice; IL-2 mRNA was not detected at any time. Increased levels of transcripts corresponding to IL-1␣, tumor necrosis factor alpha (TNF-␣), and iNOS were detected as early as day 1 postinfection, with TNF-␣ rising by ϳ30-fold and iNOS increasing by ϳ5-fold by day 7. Each remained at these levels thereafter. IL-4, IL-6, and gamma interferon transcripts were detected on day 5, and IL-1␤ and IL-10 transcripts were detected beginning on day 7. Once detected, each remained at a relatively constant level through 28 days of infection. This cytokine profile does not suggest a polarized Th1 or Th2 response. Immunohistochemistry did not reveal inflammatory infiltrates before day 7, despite the presence of cryptococci. Intraparenchymal abscesses with inflammatory cells in their peripheries were found beginning on day 10. The infiltrates were comprised primarily of cells expressing CD4, CD8, or CD11b; low numbers of cells expressing CD45R/B220 were also present. The persistence of Cryptococcus observed in the CNS may result from an ineffective immune response, perhaps owing to an insufficient anticryptococcal effector function of endogenous glial cells resulting from competing pro-and anti-inflammatory cytokines. These data detail the immune response in the brain and could be important for the future design of specific immunomodulatory therapies for this important opportunistic infection.