CD45RB expression defines two interconvertible subsets of human CD4+T cells with memory function

摘要

AbstractReciprocal 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 CD45RBbrightand 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 duringin vitroactivation 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)‐γ (mean 1.7‐fold more). MEM 1 cells consistently proliferated more (mean 2.3‐fold more) than MEM 2 cells early duringin vitroactivation. Thus, differential expression of CD45RB within CD45RA−cells defines two subsets that have similar properties except for somewhast greater IFN‐γ production and proliferative responses by MEM 1 cells. Variability in CD45RB expression may represent a mechanism for fine‐tuning the resp