ABSTRACT
4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily, is a major costimulatory receptor that is rapidly expressed on the surface of CD4+ and CD8+ T cells after antigen- or mitogen-induced activation. The interaction of 4-1BB with 4-1BBL regulates immunity and promotes the survival and expansion of activated T cells. In this study, the expression of 4-1BB and 4-1BBL was examined during regeneration of the murine thymus following acute cyclophosphamide-induced involution. Four-color flow cytometry showed that 4-1BB and 4-1BBL were present in the normal thymus and were preferentially expressed in the regenerating thymus, mainly in CD4+CD8+ double-positive (DP) thymocytes. Furthermore, the CD4loCD8lo, CD4+CD8lo and CD4loCD8+ thymocyte subsets, representing stages of thymocyte differentiation intermediate between DP and single-positive (SP) thymocytes, also expressed 4-1BB and 4-1BBL during thymus regeneration but to a lesser degree. Interestingly, the 4-1BB and 4-1BBL positive cells among the CD4+CD8+ DP thymocytes present during thymus regeneration were TCR(hi) and CD69+ unlike the corresponding controls. Moreover, the 4-1BB and 4-1BBL positive cells among the intermediate subsets present during thymus regeneration also exhibited TCRhi/int and CD69+/int phenotypes, indicating that 4-1BB and 4-1BBL are predominantly expressed by the positively selected population of the CD4+CD8+ DP and the intermediate thymocytes during thymus regeneration. RT-PCR and Western blot analyses confirmed the presence and elevated levels of 4-1BB and 4-1BBL mRNA and protein in thymocytes during thymus regeneration. We also found that the interaction of 4-1BB with 4-1BBL promoted thymocyte adhesion to thymic epithelial cells. Our results suggest that 4-1BB and 4-1BBL participate in T lymphopoiesis associated with positive selection during recovery from acute thymic involution.
Subject(s)
Animals , Male , Mice , 4-1BB Ligand/genetics , Tumor Necrosis Factor Receptor Superfamily, Member 9/genetics , CD4-Positive T-Lymphocytes/cytology , CD8-Positive T-Lymphocytes/cytology , Cell Adhesion , Cell Differentiation , Cell Line , Cells, Cultured , Cyclophosphamide/pharmacology , Epithelial Cells/cytology , Gene Expression Regulation , Immunosuppressive Agents/pharmacology , Mice, Inbred C57BL , RNA, Messenger/genetics , Regeneration , T-Lymphocytes/cytology , Thymus Gland/cytologyABSTRACT
BACKGROUND: The costimulatory molecule 4-1BB, a member of nerve growth factor receptor/tumor necrosis factor (NGFR/TNFR) super family, is involved in cell survival and death. METHODS: In this study, female C57BL/6 (H-2(b)) mice were used as a recipient, and DBA/2 (H-2(d)) as a donor to assess a mixed lymphocyte reaction (MLR) and CTL response in vitro, and skin graft survival. IL-2, IFN level was measured by ELISA. RESULTS: Mixed lymphocyte reaction (MLR) analysis showed that 4-1BB- deficient responder cells showed enhanced cellular proliferation over littermate controls. In contrast, IL-2 production was diminished only in 4-1BB knockout cultures. The IFN expression, on the other hand, was comparable between the groups. When female C57BL/6 (H-2(b)) mice were grafted with the trunk skin of DBA/2 (H-2d) mice, the in vivo tissue destruction of 4-1BB-deficient mice was not distinct from the normal littermates. CONCLUSION: These data suggest that 4-1BB is critical for the induction of alloreactive responses in vitro but 4-1BB alone could not change the course of skin rejection in vivo.
Subject(s)
Animals , Female , Humans , Mice , Allografts , Cell Proliferation , Cell Survival , Enzyme-Linked Immunosorbent Assay , Graft Survival , Hand , Interleukin-2 , Lymphocyte Culture Test, Mixed , Necrosis , Nerve Growth Factor , Skin , Tissue Donors , TransplantsABSTRACT
BACKGROUND: The costimulatory molecule 4-1BB, a member of nerve growth factor receptor/tumor necrosis factor (NGFR/TNFR) super family, is involved in cell survival and death. METHODS: In this study, female C57BL/6 (H-2(b)) mice were used as a recipient, and DBA/2 (H-2(d)) as a donor to assess a mixed lymphocyte reaction (MLR) and CTL response in vitro, and skin graft survival. IL-2, IFN level was measured by ELISA. RESULTS: Mixed lymphocyte reaction (MLR) analysis showed that 4-1BB- deficient responder cells showed enhanced cellular proliferation over littermate controls. In contrast, IL-2 production was diminished only in 4-1BB knockout cultures. The IFN expression, on the other hand, was comparable between the groups. When female C57BL/6 (H-2(b)) mice were grafted with the trunk skin of DBA/2 (H-2d) mice, the in vivo tissue destruction of 4-1BB-deficient mice was not distinct from the normal littermates. CONCLUSION: These data suggest that 4-1BB is critical for the induction of alloreactive responses in vitro but 4-1BB alone could not change the course of skin rejection in vivo.