Review: chemokines in transplantation

The alloimmune response in solid organ transplantation is characterized by antigen presentation, activation of the recipient's immune system, and an effector response. Chemokines are chemotactic cytokines and play a role in all 3 components of the alloimmune response. Early studies showed an effectiveness of chemokine receptor blockade in experimental transplant models; chemokine receptor blockers will become more widely available because of their development for other applications. This review intends to summarize the available experimental evidence surrounding chemokines in transplantation. It will first describe the inflammatory chemokine/receptor pairs IP-10/CXCR3, Regulated upon Activation, Normal T-cell Expressed and Secreted (RANTES)/CCR5, and MCP-1/CCR2 and then cover studies regarding dendritic cell trafficking, memory cell trafficking, and regulatory cell trafficking, as well as the role of chemokines in the innate immune system. The role of S1P receptors and its antagonist FTY720 will be covered because it exemplifies the importance of trafficking for the immune response. Especially as subsets of lymphocytes and dendritic cells will be better defined as far as their regulatory and memory function is concerned, chemokine targeting strategies will be important in transplantation.