Antigen-specific B cells are required for the secondary response of T cells but not for their priming

• Published in: European journal of immunology Vol. 26; no. 7; p. 1628
• Main Authors: Chowdhury, M G, Maeda, K, Yasutomo, K, Maekawa, Y, Furukawa, A, Azuma, M, Nagasawa, H, Himeno, K
• Format: Journal Article
• Language: English
• Published: Germany 01.07.1996
• Subjects: Animals; Antigen-Presenting Cells - immunology; B-Lymphocytes - immunology; B7-1 Antigen - immunology; B7-1 Antigen - metabolism; CD28 Antigens - immunology; CD28 Antigens - metabolism; Epitopes - immunology; Fetal Tissue Transplantation; Hematopoiesis - immunology; Hypersensitivity, Delayed - immunology; Immunization, Secondary; Liver Transplantation; Lymphocyte Activation; Mice; Mice, SCID; Ovalbumin - immunology; T-Lymphocytes - immunology; Thymus Gland - transplantation
• ISSN: 0014-2980
• DOI: 10.1002/eji.1830260733

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.