CD40–CD40 ligand axis (CD40–CD40L axis)

The CD40–CD40 ligand (CD40L) axis is a pivotal costimulatory pathway that regulates both innate and adaptive immune responses. CD40 is a cell surface receptor belonging to the tumor necrosis factor receptor superfamily (TNFRSF5), primarily expressed on professional antigen-presenting cells (APCs) such as dendritic cells, B cells, and macrophages (UniProt P25942). Its ligand, CD40L (CD154 or TNFSF5), is a type II transmembrane protein mainly expressed on the surface of activated CD4+ T helper cells (UniProt P29965). In the context of dendritic-fusion cells—a specialized immunotherapy where dendritic cells are fused with tumor cells—the CD40–CD40L interaction serves as a critical licensing signal. When CD40L on T cells binds to CD40 on the fusion cells, it triggers a signaling cascade that upregulates MHC molecules and costimulatory ligands (CD80/CD86) and induces the secretion of interleukin-12 (IL-12), which is essential for the induction of potent tumor-specific cytotoxic T lymphocyte (CTL) responses (PubMed 15155838). Therapeutic modulation of this axis involves two primary strategies: agonism and antagonism. CD40 agonistic antibodies, such as selicrelumab and mitazalimab, are designed to mimic CD40L signaling to enhance APC function and promote anti-tumor immunity in various cancers (ClinicalTrials.gov). Conversely, CD40–CD40L pathway inhibitors, like dapirolizumab pegol, are being developed to treat autoimmune diseases by preventing the costimulatory signals that drive pathogenic B cell and T cell activation. However, the clinical utility of these agents is often limited by safety concerns, most notably cytokine release syndrome and hepatotoxicity for agonists, and a significant risk of thromboembolic events for CD40L-targeting agents due to the presence of CD40L on platelets (PubMed 21814184).

Other names

CD40-CD154 axisCD40-TNFSF5 interactionCD40-CD40L signaling pathway

Agonism of CD40 to enhance antigen presentation and T cell priming; Blockade of CD40-CD40L interaction to inhibit costimulation in autoimmune diseases.