title: Natural killer cells prime the responsiveness of autologous CD4+ T cells to CTLA4-Ig and interleukin-10 mediated inhibition in an allogeneic dendritic cell-mixed lymphocyte reaction.
abstract: Cytotoxic T-lymphocyte antigen 4 immunoglobulin (CTLA4-Ig) and interleukin (IL)-10 are immunomodulatory molecules which target CD28 costimulation by acting either directly or indirectly on the CD80/86 receptors on dendritic cells (DCs). This study examined the effect of combined treatment with CTLA4-Ig and IL-10 on T-cell responsiveness in a dendritic cell-mixed lymphocyte reaction (DC-MLR). T cells derived from nylon wool enrichment (NWT cells) demonstrated 15% (P = 0.006) and 10% (P = 0.0015) inhibition of proliferation with suboptimal doses of IL-10 (5 ng/ml) and CTLA4-Ig (20 ng/ml), respectively. Combined treatment with both agents resulted in 38% inhibition (P = 0.004) of the MLR response compared with untreated controls. In contrast to NWT cells, which consisted of CD4+, CD8+ and CD56+ (NK) cells, purified CD4+ T cells were less responsive to immunomodulation by CTLA4-Ig and IL-10. Repletion of the CD4+ T cells with NK cells restored IL-10 and CTLA4-Ig mediated immunomodulation, suggesting a role for NK cells in the regulation of DC-T-cell interactions. The specific effect of NK cells on DC activation was demonstrated by CD80 up-regulation on DCs in the absence of T cells. However, in the absence of DCs, NK cells augmented the proliferation of autologous CD4+ T cells stimulated by anti-CD3 monoclonal antibody (mAb), which was blocked by CTLA4-Ig. It is proposed that, in the MLR, immunomodulation by suboptimal CTLA4-Ig and IL-10 is influenced by cellular interactions of NK cells with DCs and T cells involving DC lysis and costimulation. Thus, NK cells prime both DCs and T cells to low doses of CTLA4-Ig and IL-10 during alloimmune responses, providing evidence for the potential interaction between innate and adaptive immunity.
authors.affiliation: Transplantation Immunology Laboratory, Basil Hetzel Institute, The Queen Elizabeth Hospital, Woodville, South Australia, Australia.
authors.forename: Ashley
authors.initials: A
authors.lastname: Newland
authors.forename: Graeme
authors.initials: G
authors.lastname: Russ
authors.forename: Ravi
authors.initials: R
authors.lastname: Krishnan
mesh_terms: D000069594:Abatacept; D018122:B7-1 Antigen / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002450:Cell Communication / Q000276:immunology; D049109:Cell Proliferation; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D007108:Immune Tolerance; D018796:Immunoconjugates / Q000276:immunology*; D016753:Interleukin-10 / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D007959:Lymphocyte Culture Test, Mixed; D015854:Up-Regulation / Q000276:immunology
chemical_list: D018122:B7-1 Antigen; D018796:Immunoconjugates; D016753:Interleukin-10; D000069594:Abatacept