title: Migration pathways of CD4 T cell subsets in vivo: the CD45RC- subset enters the thymus via alpha 4 integrin-VCAM-1 interaction.
abstract: The present investigation examines the localization and migration of purified T cell subsets in comparison with B cells, CD8 T cells and CD4+ CD8- single-positive thymocytes. CD4 T cell subsets in the rat are defined by mAb MRC OX22 (anti-CD45RC), which distinguishes resting CD4 T cells (CD45RC+) from those (CD45RC-) which have encountered antigen in the recent past--subpopulations often referred to as 'naive' and 'memory'. Purified, 51Cr-labelled CD45RC+ CD4 T cells broadly reflected the migration pattern of CD8 T cells and B cells. Early localization to the spleen was followed by a redistribution to mesenteric lymph nodes (MLN) and cervical lymph nodes (CLN), B cells migrating at a slightly slower tempo. There was almost no localization of these subpopulations to the small or large intestine [Peyer's patches (PP) excluded]. In contrast, CD45RC- CD4 T cells (indistinguishable in size from the CD45RC+ subset) localized in large numbers to the intestine; they were present here at the earliest time point (0.5 h), persisted for at least 48 h but did not accumulate, indicating a rapid exit. Numerically, localization of CD45RC- CD4 T cells in the MLN could be accounted for entirely by afferent drainage from the intestine. Unexpectedly, CD45RC- CD4 T cells (but not other subsets) localized and accumulated in the thymus. In vivo treatment with mAb HP2/1 against the integrin alpha 4 subunit inhibited almost entirely CD45RC- CD4 T cell migration into the PP (98.1%), intestine (87.1%), MLN (89.1%) and thymus (93.5%); migration into the CLN was only reduced by half. To distinguish between recognition of MAdCAM-1 and VCAM-1 by alpha 4-containing integrins, recipients were treated with mAb 5F10 against rat VCAM-1. Except for the thymus and a small reduction in CLN, localization of CD45RC- CD4 T cells was unaffected; entry to the thymus was almost completely blocked (92.3%) by anti-VCAM-1. The results indicated (i) that CD45RC- CD4 T cells alone showed enhanced localization to the gut and PP, probably via alpha 4 beta 7-MAdCAM-1 interaction; (ii) that many CD45RC- cells entered non-mucosal LN independently of alpha 4 integrin or VCAM-1; and (iii) that entry of mature recirculating CD45RC- CD4 T cells into the thymus across thymic endothelium was apparently regulated by alpha 4 integrin-VCAM-1 interaction.
authors.affiliation: Immunology Research Group, University of Manchester, UK.
authors.forename: E B
authors.initials: EB
authors.lastname: Bell
authors.forename: S M
authors.initials: SM
authors.lastname: Sparshott
authors.forename: A
authors.initials: A
authors.lastname: Ager
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000145:classification* / Q000276:immunology* / Q000637:transplantation; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000502:physiology; D002465:Cell Movement / Q000276:immunology*; D005260:Female; D039441:Integrin alpha4; D017493:Leukocyte Common Antigens / Q000276:immunology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011923:Rats, Nude; D013950:Thymus Gland / Q000276:immunology*; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D015815:Cell Adhesion Molecules; D019010:Vascular Cell Adhesion Molecule-1; D039441:Integrin alpha4; D017493:Leukocyte Common Antigens