Antigen-specific B cells are required for the secondary response of T cells but not for their priming.
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.
Chowdhury
M G
MG
Department of Parasitology and Immunology, School of Medicine, University of Tokushima, Japan.
Maeda
K
K
Yasutomo
K
K
Maekawa
Y
Y
Furukawa
A
A
Azuma
M
M
Nagasawa
H
H
Himeno
K
K
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
D018122:B7-1 Antigen; D018106:CD28 Antigens; D000939:Epitopes; D010047:Ovalbumin