Lymphocyte-activation gene 3 (LAG3) (LAG3)

Lymphocyte-activation gene 3 (LAG3) is a cell surface receptor expressed on activated T cells, particularly regulatory T cells (Tregs), and belongs to the immunoglobulin superfamily (UniProt P18627). The specific interaction of LAG3 on Tregs with Major Histocompatibility Complex class II (MHC II) molecules on dendritic cells (DCs) is a critical regulatory pathway in the immune system (PubMed: 15034575). This binding event inhibits the maturation of dendritic cells and reduces their ability to present antigens and provide costimulatory signals to effector T cells, thereby promoting an immunosuppressive environment (Nature Reviews Cancer, 2017). In oncology, this mechanism contributes to tumor-induced immune evasion and T cell exhaustion. Therapeutic agents such as Relatlimab are designed to block the LAG3-MHC II axis, restoring the functional capacity of both dendritic cells and T cells to mount an effective anti-tumor response (FDA, 2022). Beyond cancer, modulating this interaction holds potential for treating autoimmune diseases where immune suppression is desired.

Other names

CD223Lymphocyte-activation gene 3 proteinLAG-3

LAG3 antagonists block the interaction between LAG3 on T cells and MHC class II on antigen-presenting cells, preventing inhibitory signaling and restoring T cell activation and dendritic cell maturation (Nature Reviews Cancer, 2017). Conversely, LAG3-Ig fusion proteins can act as MHC class II agonists to activate dendritic cells and enhance antigen presentation (PubMed: 15034575).