OX40, also known as TNF Receptor Superfamily Member 4 Human Recombinant (TNFRSF4) or CD134, is a member of the TNF receptor superfamily and functions as a crucial T cell co-stimulatory molecule. It coordinates with other co-stimulatory molecules like CD28, CD40, CD30, CD27, and 4-1BB to regulate immune response activation. OX40 plays a vital role in antigen-specific T cell expansion, survival, and cytokine production. Upon engagement of the TCR by antigen-presenting cells and co-stimulation by CD40-CD40L and CD28-B7, OX40 is upregulated on CD4+ and CD8+ T cells, enhancing their proliferation, survival, activation, and differentiation into effector and memory T cells. Additionally, OX40 inhibits the immunosuppressive function of regulatory T cells (Tregs) and is primarily expressed by activated antigen-presenting cells, which stimulate antigen-specific T cells through OX40/OX40L interactions.

Abbreviations: