title: Costimulatory signalling potential of murine MHC class II-positive T-clone cells.
abstract: Activated human and rat T cells as well as mouse T-cell clones have been reported to synthesize and express major histocompatibility complex (MHC) class II molecules. However, the capacity of class II+ antigen (Ag) presenting T cells to induce proliferation of Ag-specific cloned T cells has been controversial. We analysed whether the failure of some T-cell clones to proliferate in response to Ag presented by class II+ T cells is because of a lack of costimulatory cytokine production by the antigen-presenting cells (APC). As a model system the mouse class II+ cloned BI/O4.1 T cells were used as APC in order to activate the T cell clone KIII5. This T-helper 1 (Th1) type, GAT (synthetic copolymer of L-glutamic acid, L-alanine and L-tyrosine)-specific clone is characterized by an efficient downregulation of interleukin-2 receptor (IL-2R) with time following antigenic stimulation. KIII5 cells respond to GAT-presenting splenic antigen-presenting cells (APC) by IL-2 production, IL-2R upregulation and proliferation. When BI/O4.1 T cells were used as APC, KIII5 cells produced IL-2, but did not proliferate. Reverse transcriptase-polymerase chain reaction (RT-PCR) revealed a lack of IL-12 production by BI/O4.1 cells. Addition of IL-12 to a coculture of Ag-presenting BI/O4.1 cells and KIII5 cells fully reconstituted a proliferative response. IL-12 in synergy with IL-2 upregulated IL-2R alpha chain expression and enhanced proliferation of KIII5 cells. Our data suggest, that class II+ T cells are not functional in inducing Ag-mediated expansion of resting Th1 cells owing to their failure to produce IL-12, but rather that they play a role in amplification loops during an ongoing immune response.
authors.affiliation: Department of Dermatology, Johannes Gutenberg-University, Mainz, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Frosch
authors.forename: U
authors.initials: U
authors.lastname: Bonifas
authors.forename: R
authors.initials: R
authors.lastname: Ross
authors.forename: J
authors.initials: J
authors.lastname: Schwing
authors.forename: H
authors.initials: H
authors.lastname: Yagita
authors.forename: Y
authors.initials: Y
authors.lastname: Guo
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: A B
authors.initials: AB
authors.lastname: Reske-Kunz
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D002455:Cell Division / Q000276:immunology; D002460:Cell Line; D000949:Histocompatibility Antigens Class II / Q000032:analysis*; D018664:Interleukin-12 / Q000276:immunology*; D007376:Interleukin-2 / Q000096:biosynthesis; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D016133:Polymerase Chain Reaction; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D013154:Spleen / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology
chemical_list: D000949:Histocompatibility Antigens Class II; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D018664:Interleukin-12