CCR8 is a CC chcmokine receptor mostly homologous to CCR4 (44%). CCR8 mRNA has been detected in lymphoid tissues such as thymus, spleen, and lymph nodes. In particular. CCR8 message is expressed by CD4 I and CD4 I CD8 I thymocytes, and by CD4 I and CD8 I peripheral blood T lymphocytes. This pattern of expression suggests a role for this receptor and its ligands in the differentiation, and activation/migration of T lymphocytes. CCR8 may also be considered as a molecule associated with the TH2 program, being abundantly expressed by NK1.1 I CD4I cells and by TH2 cells that migrate in response to CCR8 ligands. thus suggesting an important role of 1-309 CCR8 in allergic diseases.
The main agonists of CCR8 are represented by the eukaryotic CC chemokine 1-309 and by vMIP-I, an HHV-8-encoded protein, that induce both calcium mobilization and chemotaxis in cellular transfectanls overexpressing CCR8.
A role for this receptor in modulating HIV infection is indicated by the demonstration that several HIV and SIV isolates utilize CCR8 as a coreceptor for viral entry/fusion and by the inhibition of CCR8-medialed HIV infection shown by 1-309.