ABSTRACT
Small-molecule immunosuppressive drugs (ISD) prevent graft rejection mainly by inhibiting T lymphocytes. Therapeutic immunoglobulins (IVIg) are used for substitution, antibody-mediated rejection (AbMR) and HLA-sensitized recipients by targeting distinct cell types. Since the effect of ISD and IVIg on natural killer (NK) cells remains somewhat controversial in the current literature, the aim of this comparative study was to investigate healthy donor's human NK cell functions after exposure to ISD and IVIg, and to comprehensively review the current literature. NK cells were incubated overnight with IL2/IL12 and different doses and combinations of ISD and IVIg. Proliferation was evaluated by 3[H]-thymidine incorporation; phenotype, degranulation and interferon gamma (IFNγ) production by flow cytometry and ELISA; direct NK cytotoxicity by standard 51[Cr]-release and non-radioactive DELFIA assays using K562 as stimulator and target cells; porcine endothelial cells coated with human anti-pig antibodies were used as targets in antibody-dependent cellular cytotoxicity (ADCC) assays. We found that CD69, CD25, CD54, and NKG2D were downregulated by ISD. Proliferation was inhibited by methylprednisolone (MePRD), mycophenolic acid (MPA), and everolimus (EVE). MePRD and MPA reduced degranulation, MPA only of CD56bright NK cells. MePRD and IVIg inhibited direct cytotoxicity and ADCC. Combinations of ISD demonstrated cumulative inhibitory effects. IFNγ production was inhibited by MePRD and ISD combinations, but not by IVIg. In conclusion, IVIg, ISD and combinations thereof differentially inhibit NK cell functions. The most potent drug with an effect on all NK functions was MePRD. The fact that MePRD and IVIg significantly block NK cytotoxicity, especially ADCC, has major implications for AbMR as well as therapeutic strategies targeting cancer and immune cells with monoclonal antibodies.
Subject(s)
Immunoglobulins/pharmacology , Immunosuppressive Agents/pharmacology , Killer Cells, Natural/drug effects , Cell Proliferation/drug effects , Cells, Cultured , Humans , Interferon-gamma/immunology , T-Lymphocytes/drug effectsABSTRACT
In this study we examined the effect of T cell-derived cytokines on retinal pigment epithelial (RPE) cells with respect to expression of complement components. We used an in vitro co-culture system in which CD3/CD28-activated human T cells were separated from the human RPE cell line (ARPE-19) by a membrane. Differential gene expression in the RPE cells of complement factor genes was identified using gene arrays, and selected gene transcripts were validated by q-RT-PCR. Protein expression was determined by ELISA and immunoblotting. Co-culture with activated T cells increased RPE mRNA and/or protein expression of complement components C3, factors B, H, H-like 1, CD46, CD55, CD59, and clusterin, in a dose-dependent manner. Soluble factors derived from activated T cells are capable of increasing expression of complement components in RPE cells. This is important for the further understanding of inflammatory ocular diseases such as uveitis and age-related macular degeneration.
Subject(s)
Complement System Proteins/metabolism , Gene Expression Regulation/physiology , Lymphocyte Activation/physiology , Retinal Pigment Epithelium/metabolism , T-Lymphocytes/physiology , CD28 Antigens/metabolism , CD3 Complex/metabolism , CD59 Antigens/metabolism , Cell Line , Clusterin/metabolism , Coculture Techniques , Complement C3b Inactivator Proteins/metabolism , Complement Factor H/metabolism , Dose-Response Relationship, Drug , Enzyme-Linked Immunosorbent Assay , Humans , Immunoblotting , Membrane Cofactor Protein/metabolism , Oligonucleotide Array Sequence Analysis , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Up-RegulationABSTRACT
PURPOSE: To examine the effect of human retinal pigment epithelial (RPE) cells on phytohemagglutinin (PHA) activation of T cells. METHODS: Resting peripheral blood lymphocytes (PBLs) were stimulated with PHA with or without the presence of gamma-irradiated RPE cells. Proliferation and the cell cycle profile were thereafter investigated by 3H-thymidine incorporation and flow cytometric analysis. In addition, the PBLs expression of CD69, major histocompatibility complex (MHC) class I and II, CD3, as well as the IL-2 receptor chains were evaluated by flow cytometry, and the content of IL-2 in cell culture supernatant was measured by ELISA. RESULTS: Human RPE cells were found to suppress PHA-induced proliferation, cyclin A, IL-2R-alpha and -gamma, and CD71 expression and decrease the production of IL-2; but RPE cells do not inhibit the PHA-induced expression of early activation markers CD69, MHC class I and II, and of cyclin D of the PBLs. CONCLUSIONS: These results are the first to indicate that RPE cells impede generation of activated T cells by interfering with the induction of high-affinity IL-2R-alphabetagamma, IL-2 production, and the expression of CD71 and cyclin A.
Subject(s)
Eye/immunology , Lymphocyte Activation , Pigment Epithelium of Eye/immunology , T-Lymphocytes/immunology , Antigens, CD/metabolism , Antigens, Differentiation, T-Lymphocyte/metabolism , CD3 Complex/metabolism , Cell Cycle , Cell Line , Cell Proliferation , Coculture Techniques , DNA Replication , Enzyme-Linked Immunosorbent Assay , Flow Cytometry , Histocompatibility Antigens Class I/metabolism , Histocompatibility Antigens Class II/metabolism , Humans , Immune System/physiology , Interleukin-2 Receptor alpha Subunit , Lectins, C-Type , Receptors, Interleukin/metabolismABSTRACT
The purpose of this study was to characterize the effects of human retinal pigment epithelial (RPE) cells on activated T cells. Activated T cells were cocultured with adult and foetal human RPE cells whereafter apoptosis and proliferation were determined by flow cytometry and (3)H-Thymidine incorporation assay, respectively. T cells and RPE cells were cultured directly together or in a transwell system for determination of the effect of cell contact. The importance of cell surface molecules was examined by application of a panel of blocking antibodies (CD2, CD18, CD40, CD40L, CD54, CD58) in addition to use of TCR negative T cell lines. The expression of IL2R-alpha -beta and -gamma chains of activated T cells was analysed by flow cytometry after incubation of T cells alone or with RPE cells. Human RPE cells were found to inhibit the proliferation of activated T cells by a cell contact-dependent mechanism. The RPE cells inhibitory abilities were not affected by blocking of any of the tested surface molecules. The inhibition of the T cells' proliferation correlates with a decreased expression of IL2R-beta and -gamma chains. The T cells regain their ability to proliferate and increase their IL2R-beta and -gamma chain expression within 24 hr after removal from the coculture. It is concluded that the cultured human adult and foetal RPE cells inhibit the proliferation of activated T cells by a process that does not involve apoptosis. It depends on cell contact but the involved surface molecules were not revealed. The proliferation inhibition correlates with a modulation of the T cells' expression of IL2R, and is reversible.
