title: CD45RB expression defines two interconvertible subsets of human CD4+ T cells with memory function.
abstract: Reciprocal expression of CD45RA and CD45RO in human CD4+ T cells defines populations understood to be naive cells (CD45RA+CD45RO-) and memory cells (CD45RA-CD45RO+). We investigate two subsets of CD45RA-CD45RO+ CD4+ human T cells which differ by fourfold in their expression of the CD45RB isoform; one is CD45RBbright and the other is CD45RBintermediate. In contrast, CD45RA+ naive cells are all CD45RBbright. Both subsets of CD45RA- cells proliferate in response to recall antigens so we designate them MEM 1 (CD45RO+RBbright) and MEM 2 (CD45RO+RBintermediate). CD45RA and CD45RB expression are regulated independently during in vitro activation of naive cells. When MEM 1 cells are activated they tend to down-regulate CD45RB expression, whereas activated MEM 2 cells tend to up-regulate CD45RB expression. Thus, in contrast to the stability of the CD45RA-CD45RO+ phenotype, the MEM 1 and MEM 2 phenotypes are labile and may interconvert. MEM 1 and MEM 2 cells produced comparable amounts of interleukin(IL)-2, IL-4, and IL-5 though MEM 1 cells produced slightly more interferon(IFN)-gamma (mean 1.7-fold more). MEM 1 cells consistently proliferated more (mean 2.3-fold more) than MEM 2 cells early during in vitro activation. Thus, differential expression of CD45RB within CD45RA- cells defines two subsets that have similar properties except for somewhat greater IFN-gamma production and proliferative responses by MEM 1 cells. Variability in CD45RB expression may represent a mechanism for fine-tuning the responsiveness of memory cells in vivo.
authors.affiliation: Experimental Immunology Branch, NCI, NIH, Bethesda, MD 20892.
authors.forename: K J
authors.initials: KJ
authors.lastname: Horgan
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
authors.forename: G E
authors.initials: GE
authors.lastname: Luce
authors.forename: G A
authors.initials: GA
authors.lastname: van Seventer
authors.forename: T B
authors.initials: TB
authors.lastname: Nutman
authors.forename: S
authors.initials: S
authors.lastname: Shaw
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation; D016207:Cytokines / Q000032:analysis; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory / Q000502:physiology*; D016130:Immunophenotyping; D017493:Leukocyte Common Antigens / Q000096:biosynthesis*
chemical_list: D016207:Cytokines; D017493:Leukocyte Common Antigens