title: B and T lymphocyte attenuator suppresses IL-21 production from follicular Th cells and subsequent humoral immune responses.
abstract: We recently showed that mice lacking B and T lymphocyte attenuator (BTLA), a third inhibitory coreceptor expressed on B cells and T cells, exhibit an increased Ag-specific IgG response and gradually develop hyper-gamma-globulinemia and autoantibody production. Recent studies revealed that follicular Th (Tfh) cells, which are non-Th1, non-Th2 effector T cells that express CXCR5 and provide help for B cells to produce Ig, also express BTLA. However, the role of BTLA in Tfh cell function remains unknown. In this study, we examined the regulatory role of BTLA in the development and function of Tfh cells. We found that CXCR5(+) Tfh cells expressed higher levels of BTLA than did CXCR5(-) conventional CD4(+) T cells. We also found that adoptive transfer of BTLA(-/-) CD4(+) T cells, stimulated under Tfh cell-inducing conditions (Tfh-like cells), to wild-type (WT) mice induced more Ag-specific IgG2a and IgG2b production compared with that of WT Tfh-like cells. By contrast, another adoptive-transfer experiment using BTLA(-/-) mice as recipients showed that the expression of BTLA on B cells was not involved in the regulation of Tfh-like cell-mediated Ag-specific IgG responses. Moreover, the development of IL-21-producing CXCR5(+) Tfh-like cells was significantly increased in BTLA(-/-) CD4(+) T cells compared with WT CD4(+) T cells. Furthermore, Tfh-like cell-mediated IgG responses were abolished when IL-21R(-/-) mice were used as recipients. These results suggest that BTLA signaling suppresses IL-21 production from Tfh cells and subsequent Tfh cell-mediated IgG responses.
authors.affiliation: Department of Molecular Genetics, Graduate School of Medicine, Chiba University, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kashiwakuma
authors.forename: Akira
authors.initials: A
authors.lastname: Suto
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Hiramatsu
authors.forename: Kei
authors.initials: K
authors.lastname: Ikeda
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takatori
authors.forename: Kotaro
authors.initials: K
authors.lastname: Suzuki
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Kagami
authors.forename: Koichi
authors.initials: K
authors.lastname: Hirose
authors.forename: Norihiko
authors.initials: N
authors.lastname: Watanabe
authors.forename: Itsuo
authors.initials: I
authors.lastname: Iwamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakajima
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology; D015536:Down-Regulation / Q000276:immunology*; D007108:Immune Tolerance; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000378:metabolism; D007378:Interleukins / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000502:physiology; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D008822:Mice, Transgenic; D054380:Receptors, CXCR5 / Q000378:metabolism; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism* / Q000637:transplantation; D000098546:Interleukin-21
chemical_list: C482586:BTLA protein, human; C488868:BTLA protein, mouse; C095085:CXCR5 protein, human; C513179:CXCR5 protein, mouse; D007074:Immunoglobulin G; D007378:Interleukins; D054380:Receptors, CXCR5; D011971:Receptors, Immunologic; D000098546:Interleukin-21