Natural killer cells (NKC) of a variety of host species appear to eliminate eukaryotic cells, including fungi such as Cryptococcus neoformans (Cn) and Candida albicans (Ca), by both direct cytotoxic effects and/or by indirect immunoregulatory effects on the functional responses of other immune effector cells. However, an understanding of the mechanisms these NKC responses is very incomplete, particularly as it pertains to antifungal effects of human NKC. Because elucidation of such mechanisms may be important in determining the potential relevance of NKC in host defense against opportunistic fungi, the major focus of our efforts will be to determine the direct and/or indirect effects of human NKC against both Cn and Ca and then to determine the mechanisms by which such effects occur. Direct effects against Cn and Ca will be assessed by determining the in vitro growth inhibitory/killing activity of normal and cytokine (IFN-g, IL- 2, TNF, GM-CSF)-activated human peripheral blood NKC against the fungi. Parallel assessments will also be made of the requirement for antibody (by examination of whole nonimmune and immune sera and by specific antibody fractions) in mediating NKC antifungal activity for Cn and Ca. Indirect effects against the fungi will be determined by coincubation of NKC with the critical relevant immune effector known to mediate specific resistance (i.e. monocyte/macrophage for Cn, PMN for Ca) for assessment of additive, synergistic or antagonistic effects. Studies will also be performed to determine whether soluble factors produced in culture supernatants from incubations of NKC and the fungi have effects on these phagocytes as well. Lastly, we shall determine the factors mediating direct and/or indirect NKC antifungal activity by determining (a) mechanisms of target cell interactions (directed degranulation/secretory response; participation of granules/membranes proteins; oxidative metabolism); (b) the requirement for expression of specific NKC markers and receptors in triggering antifungal effects and (c) the biochemical definition of specific patterns of intracellular responses triggered by stimulation of specific events related to changes: in membrane lipid metabolism (arachidonate release, PAF, phospholipase C and/or second messengers); in ion (Na+/K+, H+, Ca++) fluxes and concentrations in individual NKC and distributed in NKC subpopulation; in release of other mediators such as histamine/leucine; in cytoskeletal rearrangements; and in RNA transcription and protein synthesis.

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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