Candida, the most common causes of opportunistic mycoses, are increasingly important complications of transplantation, antitumor therapy, and AIDS. Neutrophils (PMN), the critical determinants of resistance to dissemination of candidiasis, can attach to and then kill opsonized or unopsonized C. albicans hyphae by a process requiring oxidant generation. Recombinant human interferon-gamma (IFN), tumor necrosis factor-alpha (TNFalpha), and a granulocyte-macrophage colony stimulating factor (GM-CSF), 3 cytokines known to enhance PMN responses, all increase hyphal-stimulated release of direct respiratory burst products but both IFN and GM-CSF augment fungicidal activity, while TNFalpha reduces it and fosters less HOC1 release, a product formed by combined respiratory burst and degranulation responses. Optimum killing efficiency requires coordinated and modulated release of oxidants and granule constituents to maximize antimicrobial cytotoxicity while minimizing adverse inflammatory effects on host cells. Since the respiratory burst and degranulation are separately regulated responses, factors controlling their coordination must be better defined. In unprimed PMN, opsonized or unopsonized hyphae and other stimuli elicit strikingly different patterns of early biochemical events, making them invaluable probes for defining signal transduction pathways. Likewise, specific opsonins are critical determinants of PMN responses, since triggering via various surface receptors elicits different specific events. A remarkable heterogeneity of responses to hyphae also is likely to affect microbicidal activity by individual PMN. Cytokines also have unique effects on PMN activation responses, some correlating with increased RNA transcription. To define molecular mechanisms for the differing effects of IFN, TNFalpha, and GM-CSF on PMN fungicidal activity, we will determine and compare changes induced by each cytokine on hypal attachment and killing responses; define receptor-specific response patterns using selectively opsonized hyphae and antireceptor monoclonal antibodies; then correlate these findings with specific patterns of activation of biochemical events (ion fluxes, patterns of activation of guanine nucleotide regulatory proteins, membrane lipid metabolism, dependence on phosphorylation mediated by protein kinase C, cytoskeleton responses, antioxidant control mechanisms) defined in individual PMN and whole PMN populations. Dependence and independence of cytokine responses on RNA and protein synthesis will be identified, and changes in RNA transcription responsible for specific, cytokine-mediated effects on the events that determine efficacy of PMN mechanisms then defined.

Project Start
Project End
Budget Start
Budget End
Support Year
4
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Boston University
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02118
Levitz, S M; Tabuni, A; Nong, S H et al. (1996) Effects of interleukin-10 on human peripheral blood mononuclear cell responses to Cryptococcus neoformans, Candida albicans, and lipopolysaccharide. Infect Immun 64:945-51
Kozel, T R; Tabuni, A; Young, B J et al. (1996) Influence of opsonization conditions on C3 deposition and phagocyte binding of large- and small-capsule Cryptococcus neoformans cells. Infect Immun 64:2336-8
Harrison, T S; Levitz, S M (1996) Role of IL-12 in peripheral blood mononuclear cell responses to fungi in persons with and without HIV infection. J Immunol 156:4492-7
Harrison, T S; Kornfeld, H; Levitz, S M (1995) The effect of infection with human immunodeficiency virus on the anticryptococcal activity of lymphocytes and monocytes. J Infect Dis 172:665-71
Meshulam, T; Levitz, S M; Christin, L et al. (1995) A simplified new assay for assessment of fungal cell damage with the tetrazolium dye, (2,3)-bis-(2-methoxy-4-nitro-5-sulphenyl)-(2H)-tetrazolium-5-carboxanil ide (XTT). J Infect Dis 172:1153-6
Sugar, A M; Picard, M; Wagner, R et al. (1995) Interactions between human bronchoalveolar macrophages and Blastomyces dermatitidis conidia: demonstration of fungicidal and fungistatic effects. J Infect Dis 171:1559-62
Stein, D K; Malawista, S E; Van Blaricom, G et al. (1995) Cytoplasts generate oxidants but require added neutrophil granule constituents for fungicidal activity against Candida albicans hyphae. J Infect Dis 172:511-20
Smail, E H; Briza, P; Panagos, A et al. (1995) Candida albicans cell walls contain the fluorescent cross-linking amino acid dityrosine. Infect Immun 63:4078-83
Levitz, S M; Dupont, M P; Smail, E H (1994) Direct activity of human T lymphocytes and natural killer cells against Cryptococcus neoformans. Infect Immun 62:194-202
Goldani, L Z; Picard, M; Sugar, A M (1994) Synthesis of heat-shock proteins in mycelia and yeast forms of Paracoccidioides brasiliensis. J Med Microbiol 40:124-8

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