title: Cutting edge: precursor frequency affects the helper dependence of cytotoxic T cells.
abstract: Generation of CTL immunity often depends on the availability of CD4 T cell help. In this report, we show that CTL responses induced by cross-priming can be converted from CD4-dependent to CD4-independent by increasing the frequency of CTL precursors. In the absence of CD4 T cells, high numbers of CTL precursors were able to expand in number and become effector CTL. The ability of high frequencies of CD8 T cells to override help was not due to their ability to signal CD40 via expression of CD154. These findings suggest that when precursor frequencies are high, priming of CD8 T cell responses may not require CD4 T cell help.
authors.affiliation: Immunology Division, Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Parkville 3050, Victoria, Australia.
authors.forename: Justine D
authors.initials: JD
authors.lastname: Mintern
authors.forename: Gayle M
authors.initials: GM
authors.lastname: Davey
authors.forename: Gabrielle T
authors.initials: GT
authors.lastname: Belz
authors.forename: Francis R
authors.initials: FR
authors.lastname: Carbone
authors.forename: William R
authors.initials: WR
authors.lastname: Heath
mesh_terms: D000818:Animals; D000941:Antigens / Q000494:pharmacology; D023201:CD40 Ligand / Q000096:biosynthesis / Q000502:physiology; D018984:Epitopes, T-Lymphocyte / Q000008:administration & dosage / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D007275:Injections, Intravenous; D008213:Lymphocyte Activation / Q000235:genetics; D018655:Lymphocyte Count; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010047:Ovalbumin / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000637:transplantation; D013234:Stem Cells / Q000166:cytology* / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology* / Q000276:immunology* / Q000637:transplantation; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D000941:Antigens; D018984:Epitopes, T-Lymphocyte; D000949:Histocompatibility Antigens Class II; D023201:CD40 Ligand; D010047:Ovalbumin