CTLA-4 Mediated Regulation of T Cell Activation

The cytotoxic T-lymphocyte antigen-4 (CTLA-4) is a pivotal inhibitory receptor that modulates the amplitude and duration of T cell responses. Expressed transiently on activated conventional T cells and constitutively on regulatory T (Treg) cells, CTLA-4 engages the co-stimulatory ligands CD80 and CD86 on antigen-presenting cells with a higher affinity than the activating receptor CD28. Engagement of CTLA-4 not only curtails TCR-induced signalling cascades by attenuating downstream kinase activation but also physically removes ligands from the presenting cell surface through transendocytosis. The dynamic trafficking of CTLA-4 between intracellular stores and the plasma membrane is regulated by a network of ubiquitylation and deubiquitylation enzymes, ensuring rapid turnover and fine tuning of inhibitory capacity. By balancing stimulatory and inhibitory inputs, CTLA-4 maintains immune homeostasis, prevents autoimmunity and shapes the efficacy of antitumour immunity. Therapeutically, blockade or modulation of CTLA-4 has revolutionised cancer treatment, while its agonism or fusion constructs have shown promise in ameliorating autoimmune and inflammatory disorders. Ongoing research continues to elucidate the molecular architecture of CTLA-4 function, its cellular partners and the implications of genetic or post-translational perturbations on global immune regulation.

Research from Nature Portfolio

Recent studies have elucidated how CTLA-4 differentiates between CD80 and CD86 ligands during transendocytosis. In the presence of CD80, CTLA-4 remains bound and undergoes ubiquitylation followed by lysosomal degradation. Conversely, interaction with CD86 is pH-dependent and triggers rapid recycling of CTLA-4 to the cell surface, permitting successive rounds of ligand capture. Mutations that disrupt CTLA-4 recycling or CD86 binding hinder efficient ligand removal, offering mechanistic explanations for certain autoimmune phenotypes and highlighting the distinct physiological roles of the two B7 ligands in immune regulation.

CTLA-4 Mediated Regulation of T Cell Activation publication trend

The graph below shows the total number of articles in ctla-4 mediated regulation of t cell activation across all publications each year (not limited to Nature Index journals).

Technical terms

CTLA-4: inhibitory receptor on T cells that limits activation by competing for ligands CD80 and CD86.

Transendocytosis: CTLA-4–mediated internalisation of ligands from antigen-presenting cells, regulating costimulation.

Ubiquitylation: attachment of ubiquitin molecules to a protein, directing its trafficking and degradation.

Nanobody: small single-domain antibody fragment derived from heavy-chain antibodies, used for targeting antigens.

Regulatory T cell (Treg): T cell subset expressing CTLA-4 that suppresses immune responses to maintain tolerance.

References

1. Differences in CD80 and CD86 transendocytosis reveal CD86 as a key target for CTLA-4 immune regulation. Nature Immunology (2022).
2. Anti-CTLA-4 nanobody as a promising approach in cancer immunotherapy. Cell Death & Disease (2024).
3. Rapid turnover of CTLA4 is associated with a complex architecture of reversible ubiquitylation. Journal of Cell Biology (2024).
4. Cancer stem cell-derived CHI3L1 activates the MAF/CTLA4 signaling pathway to promote immune escape in triple-negative breast cancer. Journal of Translational Medicine (2023).