Nonmitogenic Anti-CD3 Monoclonal Antibodies Deliver a Partial T Cell Receptor Signal and Induce Clonal Anergy

The interaction between CD95 (Fas) and CD95L (Fas ligand) initiates apoptosis in a variety of cell types. Although the regulation of CD95L expression on activated T cells is an area of intense study, knowledge related to the induction of CD95L promoter activity in primary T cells is lacking. In this report we describe the generation of a novel transgenic mouse strain, CD95LP-Luc, in which murine CD95L promoter sequence controls the expression of a luciferase reporter gene. We use these mice to illustrate several important findings related to transcriptional regulation of CD95L in primary T cells. We demonstrate that maximal CD95L promoter activity occurs only after prolonged T cell stimulation and requires costimulation through CD28. We provide evidence that thymocytes express CD95L/luciferase after strong TCR ligation and that inducible CD95L promoter activation is present, but unequal, in both Th1 and Th2 effector cells. We also illustrate that while agonist peptide presentation by APCs generates robust proliferation during a primary T cell response, the same stimulus induces only modest CD95L promoter activity. These results suggest alternate explanations for the well-characterized delay in CD95-mediated activation-induced cell death following initial ligation of the TCR.

Section: Differential Requirements For Induction Of Proliferation Vs supporting

confidence: 82%

The Regulation of CD95 (Fas) Ligand Expression in Primary T Cells: Induction of Promoter Activation in CD95LP-Luc Transgenic Mice

Norian¹,

Latinis²,

Eliason³

et al. 2000

“…In particular, naive T cells are resistant to anergy induction by Ag pulsed on 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide-fixed APC, a classical protocol leading to unresponsiveness of T cell clones (37). Similarly, exposure of naive T cells to ionomycin and nonmitogenic anti-CD3 mAbs failed to induce T cell unresponsiveness (38,39), supporting the notion that these cells are insensitive to multiple forms of anergy induction. These observations are in marked contrast with studies performed with mitogenic anti-CD3⑀ mAbs, demonstrating the sensitivity of naive T cells to this form of anergy induction (14,15).…”

Section: Discussionmentioning

confidence: 56%

Naive T Cells Are Resistant to Anergy Induction by Anti-CD3 Antibodies

Andris

Denanglaire

Mattia

et al. 2004

Anti-CD3 mAbs are potent immunosuppressive agents used in clinical transplantation. It has been generally assumed that one of the anti-CD3 mAb-mediated tolerance mechanisms is through the induction of naive T cell unresponsiveness, often referred to as anergy. We demonstrate in this study that naive T cells stimulated by anti-CD3 mAbs both in vivo and in vitro do not respond to the superantigen staphylococcal enterotoxin B nor to soluble forms of anti-CD3 mAbs and APC, but express increased reactivity to plastic-coated forms of the same anti-CD3 mAbs and to their nominal Ag/class II MHC, a finding that is difficult to rationalize with the concept of anergy. Phenotypic and detailed kinetic studies further suggest that a strong signal 1 delivered by anti-CD3 mAbs in the absence of costimulatory molecules does not lead to anergy, but rather induces naive T cells to change their mitogen responsiveness and acquire features of memory T cells. In marked contrast, Ag-experienced T cells are sensitive to anergy induction under the same experimental settings. Collectively, these studies demonstrate that exposure of naive T cells in vivo and in vitro to a strong TCR stimulus does not induce Ag unresponsiveness, indicating that sensitivity to negative signaling through TCR/CD3 triggering is developmentally regulated in CD4+ T cells.

“…The in vivo T cell-activating properties of these Abs depend on multivalent TCR cross-linking mediated via binding of the Ab Fc domains to FcRbearing cells (5). F(abЈ) 2 (6), or Abs with isotypes that do not bind FcR (7)(8)(9), allow only divalent TCR cross-linking, leading to partial signaling, Th cell hyporesponsiveness, and suppression of autoimmunity in mice (10,11). However, these nonmitogenic Abs affect all Th cells and therefore may have undesirable global immunosuppressive effects.…”

mentioning

confidence: 99%

A Single-Chain Class II MHC-IgG3 Fusion Protein Inhibits Autoimmune Arthritis by Induction of Antigen-Specific Hyporesponsiveness

Zuo

Cullen

DeLay

et al. 2002

T cells play a central role in many autoimmune diseases. A method to specifically target the function of autoreactive T cell clones would avoid the global immunosuppression associated with current therapies. To develop a molecule capable of inhibiting autoreactive T cell responses in vivo, single-chain peptide-I-A-IgG3 fusion proteins were constructed and expressed in both mammalian and insect cells. The fusion proteins were designed with an IgG3 Fc moiety to make them divalent, allowing TCR cross-linking, while lacking FcR binding and costimulation. The fusion proteins stimulated T cell hybridomas in vitro in a peptide-specific, MHC-restricted manner but failed to do so in soluble form. In vivo administration of an I-Aq fusion protein, containing an immunodominant collagen II peptide, significantly delayed the onset and reduced the severity of collagen-induced arthritis in DBA/1 mice by induction of Ag-specific hyporesponsiveness. Such fusion proteins may be useful to study novel therapeutic approaches for T cell-mediated autoimmune diseases.