[show abstract][hide abstract] ABSTRACT: Blastomyces adhesin-1 (BAD-1) is a 120-kD surface protein on B. dermatitidis yeast. We show here that BAD-1 contains 41 tandem repeats and that deleting even half of them impairs fungal pathogenicity. According to NMR, the repeats form tightly folded 17-amino acid loops constrained by a disulfide bond linking conserved cysteines. Each loop contains a highly conserved WxxWxxW motif found in thrombospondin-1 (TSP-1) type 1 heparin-binding repeats. BAD-1 binds heparin specifically and saturably, and is competitively inhibited by soluble heparin, but not related glycosaminoglycans. According to SPR analysis, the affinity of BAD-1 for heparin is 33 nM±14 nM. Putative heparin-binding motifs are found both at the N-terminus and within each tandem repeat loop. Like TSP-1, BAD-1 blocks activation of T cells in a manner requiring the heparan sulfate-modified surface molecule CD47, and impairs effector functions. The tandem repeats of BAD-1 thus confer pathogenicity, harbor motifs that bind heparin, and suppress T-cell activation via a CD47-dependent mechanism, mimicking mammalian TSP-1.
[show abstract][hide abstract] ABSTRACT: Vaccine-induced Th17 cells are necessary and sufficient to protect against fungal infection. Although live fungal vaccines are efficient in driving protective Th17 responses and immunity, attenuated fungi may not be safe for human use. Heat inactivated formulations and subunit vaccines are safer but less potent and require adjuvant to increase their efficacy. Here, we show that IL-1 enhances the capacity of weak vaccines to induce protection against lethal Blastomyces dermatitidis infection in mice and is far more effective than LPS. While IL-1 enhanced expansion and differentiation of fungus-specific T cells by direct action on those cells, cooperation with non-T cells expressing IL-1R1 was necessary to maximize protection. Mechanistically, IL-17 receptor signaling was required for the enhanced protection induced by IL-1. Thus, IL-1 enhances the efficacy of safe, but inefficient vaccines against systemic fungal infection in part by increasing the expansion of CD4 T cells, allowing their entry into the lungs, and inducing their differentiation to protective Th17 cells.
The Journal of Infectious Diseases 06/2013; · 5.85 Impact Factor
[show abstract][hide abstract] ABSTRACT: B. dermatitidis belongs to a group of thermally dimorphic fungi that grow as sporulating mold in the soil and convert to pathogenic yeast in the lung following inhalation of spores. Knowledge about the molecular events important for fungal adaptation and survival in the host remains limited. The development of high-throughput analytic tools such as RNA sequencing (RNA-Seq) has potential to provide novel insight on fungal pathogenesis especially if applied in vivo during infection. However, in vivo transcriptional profiling is hindered by the low abundance of fungal cells relative to mammalian tissue and difficulty in isolating fungal cells from the tissues they infect. For the purpose of obtaining B. dermatitidis RNA for in vivo transcriptional analysis by RNA-Seq, we developed a simple technique for isolating yeast from murine lung tissue. Using a two-step approach of filtration and centrifugation following lysis of murine lung cells, 91% of yeast cells causing infection were isolated from lung tissue. B. dermatitidis recovered from the lung yielded high-quality RNA with minimal murine contamination and was suitable for RNA-Seq. Approximately 87% of the sequencing reads obtained from the recovered yeast aligned with the B. dermatitidis genome. This was similar to 93% alignment for yeast grown in vitro. The use of near-freezing temperature along with short ex vivo time minimized transcriptional changes that would have otherwise occurred with higher temperature or longer processing time. In conclusion, we have developed a technique that recovers the majority of yeast causing pulmonary infection and yields high-quality fungal RNA with minimal contamination by mammalian RNA.
Fungal Genetics and Biology 03/2013; · 3.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: ABSTRACT Levels of the anaphylatoxin C3a are increased in patients with asthma compared with those in nonasthmatics and increase further still during asthma exacerbations. However, the role of C3a during sensitization to allergen is poorly understood. Sensitization to fungal allergens, such as Aspergillus fumigatus, is a strong risk factor for the development of asthma. Exposure to chitin, a structural polysaccharide of the fungal cell wall, induces innate allergic inflammation and may promote sensitization to fungal allergens. Here, we found that coincubation of chitin with serum or intratracheal administration of chitin in mice resulted in the generation of C3a. We established a model of chitin-dependent sensitization to soluble Aspergillus antigens to test the contribution of complement to these events. C3(-/-) and C3aR(-/-) mice were protected from chitin-dependent sensitization to Aspergillus and had reduced lung eosinophilia and type 2 cytokines and serum IgE. In contrast, complement-deficient mice were not protected against chitin-induced innate allergic inflammation. In sensitized mice, plasmacytoid dendritic cells from complement-deficient animals acquired a tolerogenic profile associated with enhanced regulatory T cell responses and suppressed Th2 and Th17 responses specific for Aspergillus. Thus, chitin induces the generation of C3a in the lung, and chitin-dependent allergic sensitization to Aspergillus requires C3aR signaling, which suppresses regulatory dendritic cells and T cells and induces allergy-promoting T cells. IMPORTANCE Asthma is one of the fastest growing chronic illnesses worldwide. Chitin, a ubiquitous polymer in our environment and a key component in the cell wall of fungal spores and the exoskeletons of insects, parasites, and crustaceans, triggers innate allergic inflammation. However, there is little understanding of how chitin is initially recognized by mammals and how early recognition of chitin affects sensitization to environmental allergens and development of allergic asthma. The complement system is evolutionarily one of the oldest facets of the early or innate warning systems in mammals. We studied whether and how complement components influence the recognition of chitin and shape the downstream sensitization toward fungal allergens. We show here that complement recognition of chitin plays a critical role in shaping the behavior of dendritic cells, which in turn regulate the function of T cells that mediate allergic responses to fungi.
[show abstract][hide abstract] ABSTRACT: Chitin exposure in the lung induces eosinophilia and alternative activation of macrophages and is correlated with allergic airway disease. However, the mechanism underlying chitin-induced polarization of macrophages is poorly understood. In this paper, we show that chitin induces alternative activation of macrophages in vivo but does not do so directly in vitro. We further show that airway epithelial cells bind chitin in vitro and produce CCL2 in response to chitin both in vitro and in vivo. Supernatants of chitin-exposed epithelial cells promoted alternative activation of macrophages in vitro, whereas Ab neutralization of CCL2 in the supernate abolished the alternative activation of macrophages. CCL2 acted redundantly in vivo, but mice lacking the CCL2 receptor, CCR2, showed impaired alternative activation of macrophages in response to chitin, as measured by arginase I, CCL17, and CCL22 expression. Furthermore, CCR2 knockout mice exposed to chitin had diminished reactive oxygen species products in the lung, blunted eosinophil and monocyte recruitment, and impaired eosinophil functions as measured by expression of CCL5, IL-13, and CCL11. Thus, airway epithelial cells secrete CCL2 in response to chitin and CCR2 signaling mediates chitin-induced alternative activation of macrophages and allergic inflammation in vivo.
The Journal of Immunology 07/2012; 189(5):2545-52. · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Vaccines may help reduce the growing incidence of fungal infections in immune-suppressed patients. We have found that, even in the absence of CD4(+) T-cell help, vaccine-induced CD8(+) T cells persist and confer resistance against Blastomyces dermatitidis and Histoplasma capsulatum. Type 1 cytokines contribute to that resistance, but they also are dispensable. Although the role of T helper 17 cells in immunity to fungi is debated, IL-17 producing CD8(+) T cells (Tc17 cells) have not been investigated. Here, we show that Tc17 cells are indispensable in antifungal vaccine immunity in hosts lacking CD4(+) T cells. Tc17 cells are induced upon vaccination, recruited to the lung on pulmonary infection, and act non-redundantly in mediating protection in a manner that requires neutrophils. Tc17 cells did not influence type I immunity, nor did the lack of IL-12 signaling augment Tc17 cells, indicating a distinct lineage and function. IL-6 was required for Tc17 differentiation and immunity, but IL-1R1 and Dectin-1 signaling was unexpectedly dispensable. Tc17 cells expressed surface CXCR3 and CCR6, but only the latter was essential in recruitment to the lung. Although IL-17 producing T cells are believed to be short-lived, effector Tc17 cells expressed low levels of KLRG1 and high levels of the transcription factor TCF-1, predicting their long-term survival and stem-cell like behavior. Our work has implications for designing vaccines against fungal infections in immune suppressed patients.
[show abstract][hide abstract] ABSTRACT: Vaccinologists strive to harness immunity at mucosal sites of pathogen entry. We studied respiratory delivery of an attenuated vaccine against Blastomyces dermatitidis. We created a T cell receptor transgenic mouse responsive to vaccine yeast and found that mucosal vaccination led to poor T cell activation in the draining nodes and differentiation in the lung. Mucosal vaccination subverted lung T cell priming by inducing matrix metalloproteinase 2 (MMP2), which impaired the action of the chemokine CCL7 on egress of CCR2(+) Ly6C(hi) inflammatory monocytes from the bone marrow and their recruitment to the lung. Studies in Mmp2(-/-) mice, or treatment with MMP inhibitor or rCCL7, restored recruitment of Ly6C(hi) monocytes to the lung and CD4(+) T cell priming. Mucosal vaccination against fungi and perhaps other respiratory pathogens may require manipulation of host MMPs in order to alter chemokine signals needed to recruit Ly6C(hi) monocytes and prime T cells at the respiratory mucosa.
[show abstract][hide abstract] ABSTRACT: Individuals who are immunocompromised, including AIDS patients with few CD4(+) T cells, are at increased risk for opportunistic fungal infections. The incidence of such infections is increasing worldwide, meaning that the need for antifungal vaccines is increasing. Although CD4(+) T cells play a dominant role in resistance to many pathogenic fungal infections, we have previously shown that vaccination can induce protective antifungal CD8(+) T cell immunity in the absence of CD4(+) T cells. However, it has not been determined whether vaccine-induced antifungal CD8(+) T cell memory can be maintained in the absence of CD4(+) T cell help. Here, we have shown in a mouse model of vaccination against blastomycosis that antifungal memory CD8(+) T cells are maintained in the absence of CD4(+) T cells without loss of numbers or function for at least 6 months and that the cells protect against infection. Using a system that enabled us to induce and track antigen-specific, antifungal CD8(+) T cells, we found that such cells were maintained for at least 5 months upon transfer into naive mice lacking both CD4(+) T cells and persistent fungal antigen. Additionally, fungal vaccination induced a profile of transcription factors functionally linked with persistent memory in CD8(+) T cells. Thus, unlike bacteria and viruses, fungi elicit long-term CD8(+) T cell memory that is maintained without CD4(+) T cell help or persistent antigen. This has implications for the development of novel antifungal vaccine strategies effective in immunocompromised patients.
The Journal of clinical investigation 03/2012; 122(3):987-99. · 15.39 Impact Factor
[show abstract][hide abstract] ABSTRACT: CD4(+) T cells are the key players of vaccine resistance to fungi. The generation of effective T cell-based vaccines requires an understanding of how to induce and maintain CD4(+) T cells and memory. The kinetics of fungal antigen (Ag)-specific CD4(+) T cell memory development has not been studied due to the lack of any known protective epitopes and clonally restricted T cell subsets with complementary T cell receptors (TCRs). Here, we investigated the expansion and function of CD4(+) T cell memory after vaccination with transgenic (Tg) Blastomyces dermatitidis yeasts that display a model Ag, Eα-mCherry (Eα-mCh). We report that Tg yeast led to Eα display on Ag-presenting cells and induced robust activation, proliferation, and expansion of adoptively transferred TEa cells in an Ag-specific manner. Despite robust priming by Eα-mCh yeast, antifungal TEa cells recruited and produced cytokines weakly during a recall response to the lung. The addition of exogenous Eα-red fluorescent protein (RFP) to the Eα-mCh yeast boosted the number of cytokine-producing TEa cells that migrated to the lung. Thus, model epitope expression on yeast enables the interrogation of Ag presentation to CD4(+) T cells and primes Ag-specific T cell activation, proliferation, and expansion. However, the limited availability of model Ag expressed by Tg fungi during T cell priming blunts the downstream generation of effector and memory T cells.
Infection and immunity 11/2011; 80(2):787-97. · 4.21 Impact Factor
[show abstract][hide abstract] ABSTRACT: We have previously reported that C57BL/6 mice vaccinated with a live, attenuated mutant of Coccidioides posadasii, referred to as the ΔT vaccine, are fully protected against pulmonary coccidioidomycosis. This model was used here to explore the nature of vaccine immunity during the initial 2-week period after intranasal challenge. Elevated neutrophil and eosinophil infiltration into the lungs of nonvaccinated mice contrasted with markedly reduced recruitment of these cells in vaccinated animals. The numbers of lung-infiltrated macrophages and dendritic cells showed a progressive increase in vaccinated mice and corresponded with reduction of the lung infection. Concentrations of selected inflammatory cytokines and chemokines were initially higher in lung homogenates of vaccinated mice but then generally decreased at 14 days postchallenge in correlation with containment of the organism and apparent dampening of the inflammation of host tissue. Profiles of cytokines detected in lung homogenates of ΔT-vaccinated mice were indicative of a mixed T helper 1 (Th1)-, Th2-, and Th17-type immune response, a conclusion which was supported by detection of lung infiltration of activated T cells with the respective CD4(+) gamma interferon (IFN-γ)(+), CD4(+) interleukin-5 (IL-5)(+), and CD4(+) IL-17A(+) phenotypes. While Th1 and Th2 immunity was separately dispensed of by genetic manipulation without loss of ΔT vaccine-mediated protection, loss of functional Th17 cells resulted in increased susceptibility to infection in immunized mice. Characterization of the early events of protective immunity to Coccidioides infection in vaccinated mice contributes to the identification of surrogates of immune defense and provides potential insights into the design of immunotherapeutic protocols for treatment of coccidioidomycosis.
Infection and immunity 08/2011; 79(11):4511-22. · 4.21 Impact Factor
[show abstract][hide abstract] ABSTRACT: Dimorphic fungi collectively account for 5-10 million new infections annually worldwide. Ongoing efforts seek to clarify mechanisms of cellular resistance to these agents and develop vaccines. A major limitation in studying the development of protective T cells in this group of organisms is the lack of tools to detect, enumerate, and characterize fungus-specific T cells during vaccination and infection. We generated a TCR transgenic mouse (Bd 1807) whose CD4(+) T cells respond to a native epitope in Blastomyces dermatitidis and also in Histoplasma capsulatum. In this study, we characterize the mouse, reveal its applications, and extend our analysis showing that 1807 cells also respond to the related dimorphic fungi Coccidioides posadasii and Paracoccidioides lutzii. On adoptive transfer into vaccinated wild-type mice, 1807 cells become activated, proliferate, and expand in the draining lymph nodes, and they differentiate into T1 effectors after trafficking to the lung upon lethal experimental challenge. Bd 1807 cells confer vaccine-induced resistance against B. dermatitidis, H. capsulatum, and C. posadasii. Transfer of naive 1807 cells at serial intervals postvaccination uncovered the prolonged duration of fungal Ag presentation. Using 1807 cells, we also found that the administration of vaccine only once induced a maximal pool of effector/memory CD4(+) cells and protective immunity by 4 wk after vaccination. The autologous adoptive transfer system described in this study reveals novel features of antifungal immunity and offers a powerful approach to study the differentiation of Ag-specific T cells responsive to multiple dimorphic fungi and the development of CD4(+) T cell memory needed to protect against fungal infection.
The Journal of Immunology 06/2011; 187(3):1421-31. · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Only a handful of the more than 100,000 fungal species on our planet cause disease in humans, yet the number of life-threatening fungal infections in patients has recently skyrocketed as a result of advances in medical care that often suppress immunity intensely. This emerging crisis has created pressing needs to clarify immune defense mechanisms against fungi, with the ultimate goal of therapeutic applications. Herein, we describe recent insights in understanding the mammalian immune defenses deployed against pathogenic fungi. The review focuses on adaptive immune responses to the major medically important fungi and emphasizes how dendritic cells and subsets in various anatomic compartments respond to fungi, recognize their molecular patterns, and signal responses that nurture and shape the differentiation of T cell subsets and B cells. Also emphasized is how the latter deploy effector and regulatory mechanisms that eliminate these nasty invaders while also constraining collateral damage to vital tissue.
Annual Review of Immunology 03/2011; 30:115-48. · 36.56 Impact Factor
[show abstract][hide abstract] ABSTRACT: Blastomycosis is a severe, commonly fatal infection caused by the dimorphic fungus Blastomyces dermatitidis in dogs that live in the United States, Canada, and parts of Africa. The cost of treating an infection can be expensive, and no vaccine against this infection is commercially available. A genetically engineered live-attenuated strain of B. dermatitidis lacking the major virulence factor BAD-1 successfully vaccinates against lethal experimental infection in mice. Here we studied the safety, toxicity, and immunogenicity of this strain as a vaccine in dogs, using 25 beagles at a teaching laboratory and 78 foxhounds in a field trial. In the beagles, escalating doses of live vaccine ranging from 2 × 10⁴ to 2 × 10⁷ yeast cells given subcutaneously were safe and did not disseminate to the lung or induce systemic illness, but a dose of < 2 × 10⁶ yeast cells induced less fever and local inflammation. A vaccine dose of 10⁵ yeast cells was also well tolerated in vaccinated foxhounds who had never had blastomycosis; however, vaccinated dogs with prior infection had more local reactions at the vaccine site. The draining lymph node cells and peripheral blood lymphocytes from vaccinated dogs demonstrated gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), and granulocyte-macrophage colony-stimulating factor (GM-CSF) specifically in response to stimulation with Blastomyces antigens. Thus, the live-attenuated vaccine against blastomycosis studied here proved safe, well tolerated, and immunogenic in dogs and merits further studies of vaccine efficacy.
[show abstract][hide abstract] ABSTRACT: Worldwide rates of systemic fungal infections, including three of the major pathogens responsible for such infections in North America (Coccidioides posadasii, Histoplasma capsulatum, and Blastomyces dermatitidis), have soared recently, spurring interest in developing vaccines. The development of Th1 cells is believed to be crucial for protective immunity against pathogenic fungi, whereas the role of Th17 cells is vigorously debated. In models of primary fungal infection, some studies have shown that Th17 cells mediate resistance, while others have shown that they promote disease pathology. Here, we have shown that Th1 immunity is dispensable and that fungus-specific Th17 cells are sufficient for vaccine-induced protection against lethal pulmonary infection with B. dermatitidis in mice. Further, vaccine-induced Th17 cells were necessary and sufficient to protect against the three major systemic mycoses in North America. Mechanistically, Th17 cells engendered protection by recruiting and activating neutrophils and macrophages to the alveolar space, while the induction of Th17 cells and acquisition of vaccine immunity unexpectedly required the adapter molecule Myd88 but not the fungal pathogen recognition receptor Dectin-1. These data suggest that human vaccines against systemic fungal infections should be designed to induce Th17 cells if they are to be effective.
The Journal of clinical investigation 02/2011; 121(2):554-68. · 15.39 Impact Factor
[show abstract][hide abstract] ABSTRACT: Early innate events that enable priming of antifungal CD4 T cells are poorly understood. We engineered an attenuated fungal vaccine with a model epitope, EalphaRFP, to track vaccine immunity to Blastomyces dermatitidis during yeast recognition, antigen presentation, and priming of naive T cells. After subcutaneous injection of the vaccine, monocyte-derived inflammatory dendritic cells (DCs) are the earliest and largest population that associates with yeast, carrying them into the draining lymph nodes. Despite marked association with yeast, these DCs fail to display surface peptide:MHC complexes or prime naive T cells. Instead, the ability to display antigen and prime CD4 T cells resides with lymph node-resident DCs after antigen transfer from immigrant DCs and with skin migratory DCs. Our work reveals the dynamic interplay among distinct DC subsets that prime naive CD4 T cells after yeast are injected in the skin and discloses the cellular elements underlying vaccine-induced immunity to fungi.
[show abstract][hide abstract] ABSTRACT: Blastomyces dermatitidis is a thermally induced dimorphic fungus capable of causing lung and systemic infections in immunocompetent animal hosts. With the publication of genomic sequences from three different strains of B. dermatitidis and the development of RNA interference as a gene-silencing tool, it has become possible to easily ascertain the virulence and morphological effects of knocking down the expression of candidate genes of interest. BYS1 (Blastomyces yeast-phase-specific 1), first identified by Burg and Smith, is expressed at high levels in yeast cells and is undetectable in mold. The deduced protein sequence of BYS1 has a putative signal sequence at its N terminus, opening the possibility that the BYS1-encoded protein is associated with the yeast cell wall. Herein, strains of B. dermatitidis with silenced expression of BYS1 were engineered and tested for morphology and virulence. The silenced strains produced rough-surfaced cultures on agar medium and demonstrated a propensity to form pseudohyphal cells on prolonged culture in vitro and in vivo, as measured in the mouse lung. Tests using a mouse model of blastomycosis with either yeast or spore inocula showed that the bys1-silenced strains were as virulent as control strains. Thus, although silencing of BYS1 alters morphology at 37 degrees C, it does not appear to impair the pathogenicity of B. dermatitidis.
Infection and immunity 04/2010; 78(6):2522-8. · 4.21 Impact Factor
[show abstract][hide abstract] ABSTRACT: Despite the well-recognized importance of CD4 T-cell help in the induction of antibody production and cytotoxic-T-lymphocyte responses, the regulation of CD4 T-cell responses is not well understood. Using mice deficient for TNF receptor I (TNFR I) and/or TNFR II, we show that TNFR I and TNFR II play redundant roles in down regulating the expansion of CD4 T cells during an acute infection of mice with lymphocytic choriomeningitis virus (LCMV). Adoptive transfer experiments using T-cell-receptor transgenic CD4 T cells and studies with mixed bone marrow chimeras indicated that indirect effects and not direct effects on T cells mediated the suppressive function of TNF on CD4 T-cell expansion during the primary response. Further studies to characterize the indirect effects of TNF suggested a role for TNFRs in LCMV-induced deletion of CD11c(hi) dendritic cells in the spleen, which might be a mechanism to limit the duration of antigenic stimulation and CD4 T-cell expansion. Consequent to enhanced primary expansion, there was a substantial increase in the number of LCMV-specific memory CD4 T cells in the spleens of mice deficient for both TNFR I and TNFR II. In summary, our findings suggest that TNFRs down regulate CD4 T-cell responses during an acute LCMV infection by a non-T-cell autonomous mechanism.
Journal of Virology 07/2007; 81(12):6502-12. · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Immunization with a cell wall/membrane (CW/M) and yeast cytosol extract (YCE) crude antigen from Blastomyces dermatitidis confers T-cell-mediated resistance against lethal experimental infection in mice. We isolated and characterized T cells that recognize components of these protective antigens and mediate protection. CD4+ T-cell clones elicited with CW/M antigen adoptively transferred protective immunity when they expressed a V alpha2+ J alpha49+/V beta1+ J beta1.1+ heterodimeric T-cell receptor (TCR) and produced high levels of gamma interferon (IFN-gamma). In contrast, V beta8.1/8.2+ CD4+ T-cell clones that were reactive against CW/M and YCE antigens and produced little or no IFN-gamma either failed to mediate protection or exacerbated the infection depending on the level of interleukin-5 expression. Thus, the outgrowth of protective T-cell clones against immunodominant antigens of B. dermatitidis is biased by a combination of the TCR repertoire and Th1 cytokine production.
Infection and Immunity 02/2007; 75(1):193-200. · 4.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: Systemic dimorphic fungi include six phylogenetically related ascomycetes. These organisms grow in a mold form in the soil on most continents around the world. After the mold spores, which are the infectious particles, are inhaled into the lung of a susceptible mammalian host, they undergo a morphological change into a pathogenic yeast form. The ability to convert to the yeast form is essential for this class of fungal agents to be pathogenic and produce disease. Temperature change is one key stimulus that triggers the phase transition from mold (25 degrees ) to yeast (37 degrees ). Genes that are expressed only in the pathogenic yeast form of these fungi have been identified to help explain how and why this phase transition is required for virulence. However, the regulators of yeast-phase specific genes, especially of phase transition from mold to yeast, have remained poorly understood. We used Agrobacterium-mediated gene transfer for insertional mutagenesis to create mutants that are defective in the phase transition and to identify genes that regulate this critical event. We discovered that a hybrid histidine kinase senses environmental signals such as temperature and regulates phase transition, dimorphism, and virulence in members of this fungal family. This chapter describes our approach to the identification and analysis of this global regulator.
Methods in Enzymology 02/2007; 422:465-87. · 2.00 Impact Factor
[show abstract][hide abstract] ABSTRACT: Cell-mediated immunity and production of type 1 cytokines are the main defenses against pathogenic fungi. Ligation of CD40 by CD40L on T cells is critical for the induction of these immune responses in vivo. We explored the role of CD40/CD40L interactions in vaccine immunity to Blastomyces dermatitidis by immunizing CD40(-/-) and CD40L(-/-) mice and analyzing their resistance to reinfection in a murine pulmonary model. In the absence of CD40 or CD40L, CD4(+) cells failed to get primed or produce type 1 cytokine and impaired the generation of CD8(+) T1 cells. The CD8(+) T cell defect was not due to regulatory T cells or impaired APC maturation or Ag presentation to T cells. If CD4(+) cells were first eliminated, vaccination of CD40(-/-) and CD40L(-/-) mice restored priming of CD8(+) cells, type 1 cytokine production, and resistance. Hence, CD4(+) and CD8(+) cells differ sharply in their requirement for CD40/CD40L interaction during the generation of antifungal immunity. Despite the plasticity of T cell subsets in vaccine immunity, in absence of CD40/CD40L interaction, CD4(+) cells may impede the priming of CD8(+) cells at the cost of host survival against a lethal infectious disease.
The Journal of Immunology 06/2006; 176(9):5538-47. · 5.52 Impact Factor