Related Experiment Videos
Identification of a murine CD28 dileucine motif that suppresses single-chain chimeric T-cell receptor expression and
Phuong Nguyen1, Ioana Moisini, Terrence L Geiger
1Department of Pathology, St Jude Children's Research Hospital, 332 N Lauderdale St, DT-4047E, Memphis, TN 38105, USA.
Abstract:
Recent preclinical and clinical trials have demonstrated the therapeutic potential of T lymphocytes redirected with genetically engineered T-cell receptor (TCR) surrogates against infected, cancerous, or autoreactive cells. These surrogate TCRs link a ligand-recognition domain to signaling regions from the TCR. We previously compared the function of surrogate TCRs that include TCR or TCR and CD28 signaling regions. We found that primary murine T cells modified to specifically target Kb-restricted CD8+ T cells using either Kb-zeta or Kb-CD28-zeta receptors had similar functional activities, although the CD28-zeta receptor showed a 2-fold to 4-fold decreased expression. We have now identified a previously unrecognized dileucine motif in the murine CD28 signaling domain that accounts for this reduced expression. Inactivation of this motif increased chimeric receptor surface expression 2- to 5-fold. T cells expressing the dileucine-mutated CD28-zeta chimeric receptor demonstrated enhanced proliferation, cytokine production, and cytolytic activities. Further, cells expressing this dileucine-mutated receptor were highly effective in eliminating antigen-specific CD8+ T lymphocytes in vivo. These results therefore identify a critical motif limiting the function of receptor-modified T lymphocytes, demonstrate that inactivation of this motif enhances chimeric receptor function, and illustrate a potential novel application of receptor-modified T lymphocytes in the induction of immune tolerance.
Insights
Scientists engineered T-cell receptor (TCR) surrogates for enhanced cancer therapy. Inactivating a specific motif in CD28 signaling domains boosted T-cell function and therapeutic efficacy in vivo.
Area of Science:
- Immunology
- Cell Biology
- Biotechnology
Background:
- Genetically engineered T-cell receptors (TCRs) show therapeutic promise for various diseases.
- Previous studies compared TCR and TCR/CD28 signaling domains, noting reduced CD28-zeta expression.
Purpose of the Study:
- Identify the cause of reduced CD28-zeta chimeric receptor expression.
- Enhance T-cell function and therapeutic potential of engineered T lymphocytes.
Main Methods:
- Investigated signaling domains of chimeric T-cell receptors.
- Utilized mutagenesis to inactivate a dileucine motif in the CD28 signaling domain.
- Assessed T-cell proliferation, cytokine production, cytolytic activity, and in vivo efficacy.
Main Results:
- Identified a dileucine motif in the CD28 signaling domain responsible for reduced receptor expression.
- Inactivating this motif increased chimeric receptor surface expression 2- to 5-fold.
- Mutated receptor-expressing T cells showed enhanced proliferation, cytokine production, cytolytic activity, and effective in vivo elimination of target cells.
Conclusions:
- A critical dileucine motif limits chimeric receptor function in T lymphocytes.
- Inactivating this motif significantly enhances engineered T-cell efficacy.
- This strategy offers a novel approach for receptor-modified T-cell therapies and immune tolerance induction.