Immune regulation by 4-1BB and 4-1BBL: complexities and challenges

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• 4-1BB (tumor necrosis factor receptor superfamily member 13B) is a key costimulatory receptor on T cells.
• It plays a significant role in T cell activation, survival, and effector function.
• The ligand for 4-1BB, 4-1BBL, is expressed on various immune and non-immune cells.

Purpose of the Study:

• To review the diverse roles of the 4-1BB/4-1BBL receptor/ligand pair in the immune response.
• To explore the mechanisms underlying the complex functions of 4-1BB signaling.
• To discuss the therapeutic implications of targeting the 4-1BB pathway.

Main Methods:

• Literature review of studies investigating 4-1BB and 4-1BBL function in various disease models.
• Analysis of data on T cell survival, proliferation, and immune response dynamics.
• Examination of signaling pathways and expression patterns of 4-1BB and 4-1BBL.

Main Results:

• 4-1BB is critical for the survival of activated and memory CD8(+) T cells.
• Its function varies depending on the disease context and expression levels of receptor and ligand.
• Studies indicate 4-1BB can prolong immune responses, especially during persistent infections.

Conclusions:

• The 4-1BB/4-1BBL axis has multifaceted roles in immunity, extending beyond T cell costimulation.
• Bidirectional signaling, receptor-independent effects of 4-1BBL, and unexpected T cell hyperproliferation in deficient cells highlight complexity.
• Understanding these complexities is vital for optimizing therapeutic strategies involving 4-1BB agonistic antibodies.