title: Loss of CD154 impairs the Th2 extrafollicular plasma cell response but not early T cell proliferation and interleukin-4 induction.
abstract: Ligation of CD40 by CD4 T cells through CD154 is key both to germinal centre induction and follicular T-dependent Ig class switching, but its requirement for aspects of T cell priming and extrafollicular antibody responses is less clear. Here comparison of the T helper (Th) type 2 response in lymph nodes from wild-type mice and CD154-deficient mice after immunization with alum-precipitated antigen reveals selective effects of this immunodeficiency. The timing and magnitude of the early interleukin (IL)-4 induction and proliferation in T cells of the T zone were unaltered by CD154 deficiency. As expected, germinal centres were not induced. Additionally the T-dependent extrafollicular antibody response, which initially requires T cell help but expands without further T cell involvement, was severely curtailed. The median number of extrafollicular antigen-specific plasma cells was 370-fold lower in CD154-deficient mice. Of these plasma cells the median proportion that had switched to IgG1 was <5%, while in wild-type mice the proportion was 89%. Surprisingly, some CD154-deficient lymph nodes showed substantial switching to IgG1. Commensurately, increases in gamma1 germline transcripts and Blimp-1 mRNA were observed, albeit significantly lower than in controls, but activation-induced cytidine deaminase mRNA was undetectable in CD154-deficient mice. These experiments demonstrate that the acquisition of some T cell priming characteristics can be CD154-independent; in contrast, T-dependent extrafollicular responses require CD154. Thus functional CD154 ligation during the first encounter of T cells and B cells in the T zone is critical for follicular and extrafollicular antibody responses.
authors.affiliation: University of Birmingham, Medical Research Council Centre for Immune Regulation, Birmingham, UK. A.F.Cunningham@bham.ac.uk
authors.forename: Adam F
authors.initials: AF
authors.lastname: Cunningham
authors.forename: Karine
authors.initials: K
authors.lastname: Serre
authors.forename: Elodie
authors.initials: E
authors.lastname: Mohr
authors.forename: Mahmood
authors.initials: M
authors.lastname: Khan
authors.forename: Kai-Michael
authors.initials: KM
authors.lastname: Toellner
mesh_terms: D000818:Animals; D000917:Antibody Formation; D019013:CD40 Antigens / Q000276:immunology; D023201:CD40 Ligand / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D003564:Cytidine Deaminase / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D018858:Germinal Center / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains; D000074462:Positive Regulatory Domain I-Binding Factor 1; D012333:RNA, Messenger / Q000235:genetics; D012097:Repressor Proteins / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D018418:Th2 Cells / Q000276:immunology*; D014157:Transcription Factors / Q000276:immunology
chemical_list: D019013:CD40 Antigens; D007074:Immunoglobulin G; C513258:Prdm1 protein, mouse; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; D023201:CD40 Ligand; D015847:Interleukin-4; D000074462:Positive Regulatory Domain I-Binding Factor 1; D003564:Cytidine Deaminase