ADP exerts P2Y 12 -dependent and P2Y 12 -independent effects on primary human T cell responses to stimulation.

Purinergic signaling plays a complex role in inflammation. Nucleotides released by T lymphocytes, endothelial cells, and platelets during inflammation induce cellular responses by binding to receptors that regulate intracellular signaling pathways. Previous studies have found that purinergic signaling can have both proinflammatory and anti-inflammatory effects, but the roles of specific pathways in specific cell types are poorly understood. We investigated the role of the P2Y ₁₂ signaling pathway in the activation of T lymphocytes in vitro. We isolated peripheral blood mononuclear cells (PBMCs) from healthy donors and pretreated them with ADP (a P2Y ₁₂ agonist), AR-C69931MX (a P2Y ₁₂ antagonist), or both. We then stimulated PBMC using phytohemagglutinin (PHA) or anti-CD3/CD28 antibodies. We found that ADP affects T cell responses in term of cell activity and receptor expression through both P2Y ₁₂ -dependent and P2Y ₁₂ -independent pathways and other responses (cytokine secretion) primarily through P2Y ₁₂ -independent pathways. The ADP-mediated effect changed over time and was stimulus-specific.