title: A conditioned dendritic cell can be a temporal bridge between a CD4+ T-helper and a T-killer cell.
abstract: To generate an immune response, antigen-specific T-helper and T-killer cells must find each other and, because they cannot detect each other's presence, they are brought together by an antigen-loaded dendritic cell that displays antigens to both. This three-cell interaction, however, seems nearly impossible because all three cell types are rare and migratory. Here we provide a potential solution to this conundrum. We found that the three cells need not meet simultaneously but that the helper cell can first engage and 'condition' the dendritic cell, which then becomes empowered to stimulate a killer cell. The first step (help) can be bypassed by modulation of the surface molecule CD40, or by viral infection of dendritic cells. These results may explain the long-standing paradoxical observation that responses to some viruses are helper-independent, and they evoke the possibility that dendritic cells may take on different functions in response to different conditioning signals.
authors.affiliation: Ghost lab, Section on T cell Tolerance and Memory, Laboratory of Cellular and Molecular Immunology, NIAID/NIH, Bethesda, Maryland 20892, USA. jridge@atlas.niaid.nih.gov
authors.forename: J P
authors.initials: JP
authors.lastname: Ridge
authors.forename: F
authors.initials: F
authors.lastname: Di Rosa
authors.forename: P
authors.initials: P
authors.lastname: Matzinger
mesh_terms: D000818:Animals; D019013:CD40 Antigens / Q000276:immunology; D023201:CD40 Ligand; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D006182:H-Y Antigen / Q000276:immunology; D066298:In Vitro Techniques; D008297:Male; D008562:Membrane Glycoproteins / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D018345:Mice, Knockout; D018448:Models, Immunological; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D019013:CD40 Antigens; D006182:H-Y Antigen; D008562:Membrane Glycoproteins; D023201:CD40 Ligand