Role for CCR7 ligands in the emigration of newly generated T lymphocytes from the neonatal thymus.
Ueno T,
Hara K,
Willis MS,
Malin MA,
Höpken UE,
Gray DH,
Matsushima K,
Lipp M,
Springer TA,
Boyd RL,
Yoshie O,
Takahama Y.
Division of Experimental Immunology, Institute for Genome Research, The University of Tokushima and Laboratory of Immune System Development, RIKEN Research Center for Allergy and Immunology, 3-18-15 Kuramoto, 770-8503, Tokushima, Japan.
Most T lymphocytes are generated within the thymus. It is unclear, however, how newly generated T cells relocate out of the thymus to the circulation. The present study shows that a CC chemokine CCL19 attracts mature T cells out of the fetal thymus organ culture. Another CC chemokine CCL21, which shares CCR7 with CCL19 but has a unique C-terminal extension containing positively charged amino acids, failed to show involvement in thymic emigration. Neonatal appearance of circulating T cells was defective in CCL19-neutralized mice as well as in CCR7-deficient mice but not in CCL21-neutralized mice. In the thymus, CCL19 is predominantly localized in the medulla including endothelial venules. These results indicate a CCL19- and CCR7-dependent pathway of thymic emigration, which represents a major pathway of neonatal T cell export.
PMID: 11869682 [PubMed - indexed for MEDLINE]