Extracellular ATP-Adenosine-Interleukin-2 Signaling Axis (ATP-ADO-IL2 Axis) (ATP-ADO-IL2 Axis)

The extracellular ATP-adenosine-interleukin-2 (ATP-ADO-IL2) signaling axis is a complex immunoregulatory network that governs the balance between immune activation and suppression in inflamed tissues and the tumor microenvironment. In this pathway, extracellular ATP released by stressed cells acts as a pro-inflammatory signal but is rapidly converted into immunosuppressive adenosine by the ecto-enzymes CD39 and CD73 (Antonioli et al., 2013). Adenosine subsequently signals through purinergic receptors, primarily the A2A receptor, to suppress the activity of effector T-cells and Natural Killer cells. Crucially, adenosine signaling has been shown to inhibit the production and downstream signaling of Interleukin-2 (IL-2), which is essential for T-cell proliferation and survival (Vijayan et al., 2017). In the context of cancer, this axis is often exploited to create a metabolic barrier against anti-tumor immunity, whereas in autoimmune conditions, it may be dysregulated, leading to impaired regulatory T-cell function. Therapeutic strategies targeting this axis include the use of CD39 and CD73 inhibitors to prevent adenosine accumulation and adenosine receptor antagonists to block suppressive signaling (Sitkovsky et al., 2004). Additionally, IL-2 agonists or low-dose IL-2 therapies are employed to restore the balance of effector versus regulatory immune cells (Malek, 2008). This integrated pathway is a major focus of modern immunotherapy, as it links metabolic checkpoints with cytokine-driven immune responses. Monitoring biomarkers such as CD73 expression and extracellular adenosine levels is critical for patient selection in clinical trials targeting this axis. Overall, the ATP-ADO-IL2 axis represents a multifaceted therapeutic target for treating both oncology and inflammatory disorders.

Other names

Purinergic-IL2 signaling pathwayCD39-CD73-Adenosine-IL2 axisExtracellular purine metabolism and cytokine signaling axis

Inhibition of ectonucleotidases (CD39/CD73) to prevent adenosine accumulation, antagonism of adenosine receptors to block immunosuppressive signaling, and agonism of IL-2 receptors to promote T-cell activation and proliferation.