Chemokines are typically 8-10 kilodaltons in mass and contain four conserved cysteine residues essential for their three-dimensional structure . They are expressed in various tissues and have distinct expression patterns. Some chemokines are constitutively expressed, while others are induced in response to inflammatory stimuli . Their tissue distribution includes sites of inflammation, lymphoid organs, and other tissues where they play roles in immune surveillance and homeostasis .

The primary function of chemokines is to act as chemoattractants, guiding the migration of cells towards higher concentrations of chemokines . They play crucial roles in immune responses by recruiting immune cells to sites of infection or injury . Chemokines are also involved in pathogen recognition and the activation of host immune responses . Additionally, they regulate processes such as morphogenesis, wound healing, and angiogenesis .

Chemokines exert their effects by binding to G protein-coupled receptors (GPCRs) on the surface of target cells . This binding triggers intracellular signaling cascades, including calcium signaling and the activation of small GTPases . These signaling events lead to changes in cell adhesion, actin polymerization, and cell movement . Chemokines also interact with other molecules, such as integrins, to facilitate cell migration .

The expression and activity of chemokines are tightly regulated at multiple levels. Transcriptional regulation involves the activation of specific genes in response to inflammatory stimuli . Post-transcriptional mechanisms include mRNA splicing and degradation . Post-translational modifications, such as phosphorylation and glycosylation, can also modulate chemokine activity . Additionally, atypical chemokine receptors act as decoys to regulate chemokine availability .

Chemokines have significant applications in biomedical research, serving as diagnostic tools and therapeutic targets . They are used to study immune responses, inflammation, and cancer metastasis . In diagnostics, chemokine levels can indicate disease states or the presence of infections . Therapeutically, chemokine receptor antagonists are being developed to treat inflammatory diseases and cancer .

Chemokines play essential roles throughout the life cycle, from development to aging and disease . During development, they guide cell migration and tissue organization . In adulthood, they maintain immune surveillance and tissue homeostasis . In aging and disease, dysregulated chemokine activity can contribute to chronic inflammation, autoimmune diseases, and cancer .