Multiple levels of activation of murine CD8(+) intraepithelial lymphocytes defined by OX40 (CD134) expression: effects on cell-mediated cytotoxicity, IFN-gamma, and IL-10 regulation.
The involvement of OX40 (CD134) in the activation of CD8(+) intestinal intraepithelial lymphocytes (IELs) has been studied using freshly isolated IELs and in vitro CD3-stimulated IELs. Although freshly isolated CD8(+) IELs exhibited properties of activated T cells (CD69 expression and ex vivo cytotoxicity), virtually all CD8(+) IELs from normal mice were devoid of other activation-associated properties, including a lack of expression of OX40 and the ligand for OX40 (OX40L) and an absence of intracellular IFN-gamma staining. However, OX40 and OX40L expression were rapidly up-regulated on CD8 IELs following CD3 stimulation, indicating that both markers on IELs reflect activation-dependent events. Unlike IELs, activated lymph node T cells did not express OX40L, thus indicating that OX40-OX40L communication in the intestinal epithelium is part of a novel CD8 network. Functionally, OX40 expression was exclusively associated with IELs with active intracellular IFN-gamma synthesis and markedly enhanced cell-mediated cytotoxicity. However, OX40 costimulation during CD3-mediated activation significantly suppressed IL-10 synthesis by IELs, whereas blockade of OX40-OX40L by anti-OX40L mAb markedly increased IL-10 production. These findings indicate that: 1) resident CD69(+)OX40(-) IELs constitute a population of partially activated T cells poised for rapid delivery of effector activity, 2) OX40 and OX40L expression defines IELs that have undergone recent immune activation, 3) OX40(+) IELs are significantly more efficient CTL than are OX40(-) IELs, and 4) the local OX40/OX40L system plays a critical role in regulating the magnitude of cytokine responses in the gut epithelium.
Wang
H C
HC
Department of Basic Sciences, Dental Branch, University of Texas Health Science Center, Houston, TX 77030, USA.
Klein
J R
JR
D000818:Animals; D017252:CD3 Complex / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis*; D003602:Cytotoxicity, Immunologic; D005260:Female; D018928:Immunity, Mucosal; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000096:biosynthesis; D016753:Interleukin-10 / Q000096:biosynthesis; D007413:Intestinal Mucosa / Q000166:cytology / Q000276:immunology*; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018448:Models, Immunological; D053278:OX40 Ligand; D053262:Receptors, OX40; D018124:Receptors, Tumor Necrosis Factor; D016176:T-Lymphocyte Subsets / Q000145:classification; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000378:metabolism*; D048069:Tumor Necrosis Factors
D017252:CD3 Complex; D016207:Cytokines; D008562:Membrane Glycoproteins; D053278:OX40 Ligand; D053262:Receptors, OX40; D018124:Receptors, Tumor Necrosis Factor; C505717:Tnfrsf4 protein, mouse; C504586:Tnfsf4 protein, mouse; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D048069:Tumor Necrosis Factors; D016753:Interleukin-10; D007371:Interferon-gamma