Function of CD4 T cell subsets in vivo: expression of CD45R isoforms.
Currently high (hi) and low (lo) molecular weight isoforms of CD45R are used to identify naive and memory T cells. However, CD45R isoforms were found to be expressed cyclically on CD4 T cells in vivo. A switch in isoform paralleled a change of function. During early post-thymic development, a switch from CD45Rlo to CD45Rhi occurred prior to antigen encounter. Naive CD45Rhi T cells when stimulated by antigen became CD45Rlo but reverted to CD45Rhi with time. It is argued that CD45Rlo T cells functionally resemble effector T cells and are at a pivotal stage of differentiation. Many are equipped to migrate into sites of inflammation. Removed from antigen, antigen-primed CD45Rlo T cells become CD45Rhi (memory) and thus adopt the same phenotype as naive T cells.
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Immunology Research Group, University Medical School, Manchester, UK.
D000818:Animals; D000941:Antigens / Q000276:immunology; D015703:Antigens, CD / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D002454:Cell Differentiation; D002465:Cell Movement; D015870:Gene Expression; D006649:Histocompatibility Antigens / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007156:Immunologic Memory; D017493:Leukocyte Common Antigens; D008211:Lymphocyte Cooperation; D008222:Lymphokines / Q000378:metabolism; D012326:RNA Splicing; D051381:Rats; D011923:Rats, Nude / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology
D000941:Antigens; D015703:Antigens, CD; D006649:Histocompatibility Antigens; D008222:Lymphokines; D017493:Leukocyte Common Antigens