title: Effects of tumor necrosis factor alpha on dendritic cell accumulation in lymph nodes draining the immunization site and the impact on the anticryptococcal cell-mediated immune response.
abstract: Cell-mediated immune (CMI) responses and tumor necrosis factor alpha (TNF-alpha) have been shown to be essential in acquired protection against Cryptococcus neoformans. Induction of a protective anticryptococcal CMI response includes increases in dendritic cells (DC) and activated CD4(+) T cells in draining lymph nodes (DLN). During the expression phase, activated CD4(+) T cells accumulate at a peripheral site where cryptococcal antigen is injected, resulting in a classical delayed-type hypersensitivity (DTH) reaction. Induction of a nonprotective anticryptococcal CMI response results in no significant increases in the numbers of DC or activated CD4(+) T cells in DLN. This study focuses on examining the role of TNF-alpha in induction of protective and nonprotective anticryptococcal CMI responses. We found that neutralization of TNF-alpha at the time of immunization with the protective immunogen (i) reduces the numbers of Langerhans cells, myeloid and lymphoid DC, and activated CD4(+) T cells in DLN and (ii) diminishes the total numbers of cells, the numbers of activated CD4(+) T cells, and amount of gamma interferon at the DTH reaction site. Although TNF-alpha neutralization during induction of the nonprotective CMI response had little effect on cellular and cytokine parameters measured, it did cause a reduction in footpad swelling when mice received challenge in the footpad. Our findings show that TNF-alpha functions during induction of the protective CMI response by influencing the accumulation of all three DC subsets into DLN. Without antigen stimulated DC in DLN, activated CD4(+) T cells are not induced and thus not available for the expression phase of the CMI response.
authors.affiliation: Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA.
authors.forename: Sean K
authors.initials: SK
authors.lastname: Bauman
authors.forename: Gary B
authors.initials: GB
authors.lastname: Huffnagle
authors.forename: Juneann W
authors.initials: JW
authors.lastname: Murphy
mesh_terms: D000818:Animals; D000946:Antigens, Fungal / Q000008:administration & dosage / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D003453:Cryptococcosis / Q000276:immunology / Q000517:prevention & control*; D003455:Cryptococcus neoformans / Q000276:immunology*; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D005657:Fungal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007111:Immunity, Cellular; D007114:Immunization; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000378:metabolism*
chemical_list: D000946:Antigens, Fungal; D005657:Fungal Vaccines; D014409:Tumor Necrosis Factor-alpha