Immunological synapse formation licenses CD40-CD40L accumulations at T-APC contact sites.

The maintenance of tolerance is likely to rely on the ability of a T cell to polarize surface molecules providing "help" to only specific APCs. The formation of a mature immunological synapse leads to concentration of the TCR at the APC interface. In this study, we show that the CD40-CD154 receptor-ligand pair is also highly concentrated into a central region of the synapse on mouse lymphocytes only after the formation of the TCR/CD3 c-SMAC.

New views of the immunological synapse: variations in assembly and function.

The interaction of T cells with antigen-presenting cells results in the formation of a contact face, termed the immunological synapse. The prototypical dynamics of this process are well established and involve cessation of crawling, a highly fluid 'immature' synapse phase during which signaling is initiated, and ultimately the formation of a 'mature' synapse characterized by centralized and peripheral supramolecular activating complexes. Ongoing research is directed towards defining how these supramolecular assemblies are formed and, more importantly, to what end.

Liver-infiltrating lymphocytes in end-stage hepatitis C virus: subsets, activation status, and chemokine receptor phenotypes.

Background: Hepatitis C virus (HCV) is a leading cause of chronic liver disease, yet little is known about the intrahepatic immune response in end-stage patients. Chemokines and their receptors are important regulators of immunity, particularly in the migration and localization of circulating leukocytes within peripheral tissues.

Aims: This report provides a comprehensive comparison of the chemokine receptor and activation phenotype of the major leukocyte subsets present in end-stage HCV-infected and non-HCV infected livers.

Expression of the chemokine receptors CCR4, CCR5, and CXCR3 by human tissue-infiltrating lymphocytes.

Differential expression of adhesion molecules and chemokine receptors has been useful for identification of peripheral blood memory lymphocyte subsets with distinct tissue and microenvironmental tropisms. Expression of CCR4 by circulating memory CD4(+) lymphocytes is associated with cutaneous and other systemic populations while expression of CCR9 is associated with a small intestine-homing subset. CCR5 and CXCR3 are also expressed by discrete memory CD4(+) populations in blood, as well as by tissue-infiltrating lymphocytes from a number of sites.