ABSTRACT
BACKGROUND: B cell depletion has been employed to treat antibody-mediated organ transplantation rejection, although the effects on cellular immune responses have not been extensively investigated. METHODS: A model of B cell depletion used SCID/beige mice reconstituted with BALB/c splenocytes either depleted of B cells (BD) or not (BN). BD and B/N mice received C57BL/6 skin grafts and were sacrificed after 6 weeks (BD-S6 and BN-S6). RESULTS: Recall proliferative responses of BD-S6 splenocytes to C57BL/6 were significantly reduced compared to BN-S6, and central memory T cells' proportions (CD4(+)CD44(+)CD62L(+) or CD8(+)CD44(+)CD62L(+)) were significantly decreased in BD-S6 spleens. Recall IFN-gamma production by BD-S6 splenocytes was significantly reduced compared to BN-S6 splenocytes (p=0.0028). Survival times of C57BL/6 heart grafts were significantly longer in SCID/beige mice reconstituted with BD-S6 splenocytes (8.5+/-1.1 days) than for SCID/beige reconstituted with BN-S6 splenocytes (6.0+/-1.1 days; p=0.0006). Under cyclosporine therapy, C57BL/6 heart survival was significantly longer for SCID/beige reconstituted with BD-S6 splenocytes (17.5+/-6.4 days) than those reconstituted with BN-S6 splenocytes (6.2+/-1.5 days; p<0.0001). CONCLUSION: B cell depletion during allogeneic sensitization decreased memory T cells and recalls IFN-gamma production and reduced second-set allograft rejection.
Subject(s)
B-Lymphocytes/metabolism , Graft Rejection/immunology , Lymphocyte Depletion , T-Lymphocytes/metabolism , Transplantation Conditioning , Animals , Antigens, CD/metabolism , B-Lymphocytes/immunology , B-Lymphocytes/pathology , Cell Proliferation , Graft Rejection/metabolism , Graft Rejection/pathology , Graft Rejection/prevention & control , Immunologic Memory , Immunosuppression Therapy , Interferon-gamma/metabolism , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, SCID , Skin Transplantation , T-Lymphocytes/immunology , T-Lymphocytes/pathology , Transplantation ChimeraABSTRACT
BACKGROUND: CD152 has been implicated in tolerance induction. This study investigated how CD80 and CD86 regulated CD152 expression in a low-responding cardiac transplant model with CD152-mediated long-term graft acceptance. METHODS: A low-responding cardiac transplant model from BALB/c to B10.A was used. Donor-specific stimulation and multiple antibody blockade of the CD80/CD86:CD28/CD152 co-stimulatory pathway was applied to the splenic T cells from B10.A recipients with 100-day grafts (B10.A-100). Proliferation assays, quantitative (Q) real-time polymerase chain reaction (PCR), flow cytometric analyses, and fluorescence microscopy were conducted to examine the roles of CD80 and CD86 in CD152 expression. RESULTS: B10.A-100 splenic T cells were hyporesponsive to donor-specific stimulation, and anti-CD80, anti-CD86, or anti-CD152 treatment significantly enhanced the proliferation response of the B10.A-100 splenic T cells. Proliferation assays and Q-PCR revealed that CD152 inhibited T-cell proliferation and, at the same time, decreased CD152 expression by secluding CD80 and CD86 from CD28 engagement. Flow cytometric analyses and fluorescence microscopy showed that CD28 engagement facilitated intracellular accumulation of CD152. Besides, CD152 engagement by CD80 decreased CD152 mRNA transcription, and CD152 engagement by CD86 inhibited surface expression of CD152. CONCLUSIONS: CD80 and CD86 controlled CD152-mediated allograft tolerance by multiple negative feedbacks on CD152 mRNA and surface expression.
