Leukocytes respond to complex patterns of chemoattractant cytokine (chemokine) gradients that guide them to their destinations in secondary lymphoid organs. This directed movement of multiple cell types requires the choreographed expression of specific G-protein-coupled chemokine receptors and both positive and negative regulation of the signal transduction pathways emanating from them.
Jung, S. (1999). Chemokine receptors in lymphoid organ homeostasis. Current Opinion in Immunology. Current Biology Ltd. https://doi.org/10.1016/S0952-7915(99)80051-X