title: Antigen-specific B cells are required for the secondary response of T cells but not for their priming.
abstract: We studied the potential role of B cells in T cell responses using severe-combined immunodeficient (SCID) mice grafted with the thymus from fetal C.B-17 mice (TG mice). These mice developed both CD4+ and CD8+ T cells, but not B cells within 2 months after transplantation. TG mice showed normal delayed-type hypersensitivity responses against the immunizing antigen ovalbumin (OVA). Lymph node (LN) cells of TG mice proliferated well in response to concanavalin A (Con A). Further, Con A stimulation induced the production of interleukin (IL)-2, IL-6 and interferon (IFN)-gamma and the expression of IL-4 mRNA. Thus, TG mice were reconstituted without remarkable immunodeficiency. However, these T cells failed to proliferate to OVA stimulation. Response to OVA was also inhibited in SCID mice grafted with fetal C.B-17 liver cells when B cells were depleted in the proliferation assay. Unresponsiveness against immunizing antigen was restored by the addition of antigen-primed B cells, but not by naive B cells, lipopolysaccharide-activated B cells or B cells primed with sheep red blood cells. Next, we examined whether antigen-primed B cells could induce T cell responses without professional antigen-presenting cells (APC). T and B cells were purified from OVA-immunized mice by cell sorter. These T cells proliferated in response to OVA and produced IFN-gamma in the absence of non-B APC. When anti-CD80 or anti-CD86 was added in the assay, proliferation and IFN-gamma production was inhibited. These results indicate that B cells activated specifically with antigen are required for the secondary response of T cells, but not for their priming.
authors.affiliation: Department of Parasitology and Immunology, School of Medicine, University of Tokushima, Japan.
authors.forename: M G
authors.initials: MG
authors.lastname: Chowdhury
authors.forename: K
authors.initials: K
authors.lastname: Maeda
authors.forename: K
authors.initials: K
authors.lastname: Yasutomo
authors.forename: Y
authors.initials: Y
authors.lastname: Maekawa
authors.forename: A
authors.initials: A
authors.lastname: Furukawa
authors.forename: M
authors.initials: M
authors.lastname: Azuma
authors.forename: H
authors.initials: H
authors.lastname: Nagasawa
authors.forename: K
authors.initials: K
authors.lastname: Himeno
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D018122:B7-1 Antigen / Q000276:immunology / Q000378:metabolism; D018106:CD28 Antigens / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000276:immunology*; D016332:Fetal Tissue Transplantation; D006410:Hematopoiesis / Q000276:immunology; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007117:Immunization, Secondary; D016031:Liver Transplantation; D008213:Lymphocyte Activation; D051379:Mice; D016513:Mice, SCID; D010047:Ovalbumin / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000637:transplantation
chemical_list: D018122:B7-1 Antigen; D018106:CD28 Antigens; D000939:Epitopes; D010047:Ovalbumin