autokrine

Autocrine signaling, also spelled autokrine in some languages, is a mode of cell communication in which a cell secretes signaling molecules that bind to receptors on the same cell or on genetically identical cells within the same population, forming an autocrine loop. This signaling can regulate processes such as growth, differentiation, survival, and function.

Typical autocrine signals are cytokines and growth factors, including interleukins such as IL-2 in immune cells or epidermal growth factor–like ligands in various tissues. Autocrine loops can reinforce a cellular state, promote proliferation, or coordinate responses, and are subject to regulation by receptor desensitization, ligand degradation, and feedback inhibitors.

Autocrine signaling is distinct from paracrine signaling (affecting nearby cells), endocrine signaling (via the bloodstream to distant targets), and juxtacrine signaling (requiring direct cell contact). Receptors for autocrine ligands often belong to cytokine receptors, receptor tyrosine kinases, or G protein–coupled receptors, triggering pathways such as JAK–STAT or MAPK.

Dysregulation of autocrine loops is implicated in disease, notably cancer, where tumor cells may rely on self-produced growth factors for growth and survival, and in inflammatory or autoimmune conditions. Studying autocrine signaling helps illuminate mechanisms of tissue development, immune regulation, and pathological states.