title: Listeria monocytogenes infection overcomes the requirement for CD40 ligand in exogenous antigen presentation to CD8(+) T cells.
abstract: In vivo priming of CD8(+) T lymphocytes against exogenously processed model Ags requires CD4(+) T cell help, specifically interactions between CD40 ligand (CD40L) expressed by activated CD4(+) T cells and CD40, which is present on professional APC such as dendritic cells (DCs). To address this issue in the context of bacterial infection, we examined CD40L-CD40 interactions in CD8(+) T cell priming against an exogenously processed, nonsecreted bacterial Ag. CD40L interactions were blocked by in vivo treatment with anti-CD40L mAb MR-1, which inhibited germinal center formation and CD8(+) T cell cross-priming against an exogenous model Ag, OVA. In contrast, MR-1 treatment did not interfere with CD8(+) T cell priming against a nonsecreted or secreted recombinant Ag expressed by Listeria monocytogenes. Memory and secondary responses of CD8(+) T cells against nonsecreted and secreted bacterial Ags were also largely unimpaired by transient MR-1 treatment. When MR-1-treated mice were concurrently immunized with L. monocytogenes and OVA-loaded splenocytes, cross-priming of OVA-specific naive CD8(+) T cells occurred. No significant decline in cross-priming against OVA was measured when either TNF or IFN-gamma was neutralized in L. monocytogenes-infected animals, demonstrating that multiple signals exist to overcome CD40L blockade of CD8(+) T cell cross-priming during bacterial infection. These data support a model in which DCs can be stimulated in vivo through signals other than CD40, becoming APC that can effectively stimulate CD8(+) T cell responses against exogenous Ags during infection.
authors.affiliation: Interdisciplinary Program in Immunology, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Hamilton
authors.forename: A R
authors.initials: AR
authors.lastname: Tvinnereim
authors.forename: J T
authors.initials: JT
authors.lastname: Harty
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D017951:Antigen Presentation; D000942:Antigens, Bacterial / Q000276:immunology; D023201:CD40 Ligand / Q000276:immunology / Q000502:physiology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D002478:Cells, Cultured; D005260:Female; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology; D008089:Listeria monocytogenes / Q000235:genetics / Q000276:immunology; D008088:Listeriosis / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000276:immunology; D011994:Recombinant Proteins / Q000276:immunology; D013154:Spleen / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000502:physiology
chemical_list: D000906:Antibodies; D000942:Antigens, Bacterial; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D023201:CD40 Ligand; D007371:Interferon-gamma; D010047:Ovalbumin