title: Regulation of tissue-selective T-lymphocyte homing receptors during the virgin to memory/effector cell transition in human secondary lymphoid tissues.
abstract: Conventional virgin T cells efficiently and homogeneously recirculate through all secondary lymphoid tissues, but not "extralymphoid" effector sites. In contrast, memory/effector populations are composed of distinct subsets with differential, often tissue-selective, migratory capability to both secondary lymphoid tissues and effector sites. In keeping with these observations, CD45RA(high)/RO(low) virgin T cells in human peripheral blood uniformly express the peripheral lymph node (PLN) homing receptor (HR) L-selectin, and lack the skin-selective HR CLA, whereas among the CD45RA(low)/RO(high) "memory/effector" population, differential expression of these HR yields three predominant subsets: L-selectin+/CLA+, L-selectin+/CLA-, L-selectin-/CLA-. Although these subsets are of approximately equal size in the peripheral blood, the vast majority of T cells obtained from cutaneous chronic inflammatory sites display the L-selectin+/CLA+ phenotype. To investigate the mechanisms responsible for the generation of these memory/effector T-cell subsets, we developed a multiparameter flow cytometric technique that defines a common pathway of postthymic T-cell differentiation in secondary lymphoid tissues: the virgin to memory/effector transition. Our analyses indicate that these HR are differentially regulated during the virgin to memory/effector transition in a tissue-specific fashion. The great majority of memory/effector T cells produced in PLN retain high levels of L-selectin expression, and 50 to 60% upregulate CLA. In contrast, memory/effector T cells produced in appendix and tonsil are generally L-selectin(low), and CLA is upregulated on less than 10% of newly formed memory/effector T cells in appendix and on about 30 to 35% of such cells in tonsil.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pathology, University of Texas Southwestern Medical Center, Dallas.
authors.forename: L J
authors.initials: LJ
authors.lastname: Picker
mesh_terms: D000328:Adult; D001769:Blood / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000276:immunology; D005434:Flow Cytometry / Q000295:instrumentation / Q000379:methods; D006801:Humans; D007156:Immunologic Memory / Q000276:immunology*; D019041:L-Selectin; D017493:Leukocyte Common Antigens / Q000276:immunology; D008221:Lymphoid Tissue / Q000276:immunology*; D010920:Placenta; D016201:Receptors, Lymphocyte Homing / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D017252:CD3 Complex; D015815:Cell Adhesion Molecules; D016201:Receptors, Lymphocyte Homing; D019041:L-Selectin; D017493:Leukocyte Common Antigens