A novel subpopulation of CD45RA+ CD4+ T cells expressing IL-2 receptor alpha-chain (CD25) and having a functionally transitional nature into memory cells.
Differential expression of various isoforms of leukocyte common antigen (CD45), which arises from alternate mRNA splicing, identifies naive and memory populations of human T cells. Some memory (CD45RO+ CD45RA-) populations of CD4+ T cells from adult individuals express IL-2 receptor (IL-2R) alpha-chain (CD25), but naive (CD45RO- CD45RA+) CD4+ T cells only do so to a small degree. We found that a small but significant fraction of CD4+ T cells in neonatal blood expressed CD25, although most generally exhibited the phenotype of naive cells. It was demonstrated that purified neonatal CD25+ CD4+ T cells expressed mRNA for the IL-2R alpha-chain. Two-color immunofluorescence analysis disclosed that a CD25+ population of neonatal CD4+ T cells had the naive (CD45RA+ CD45RO-) phenotypes. These CD25+ CD4+ T cells from newborns could express mRNA for some specified lymphokines such as IL-4, IL-5, and interferon-gamma on activation in a similar manner to CD45RO+ (memory) CD4+ T cells from adults. Notably, polymerase chain reaction analysis demonstrated that neonatal CD45RA+ CD4+ T cells expressing CD25 contained spliced mRNA transcripts possibly encoding CD45RO in addition to CD45RA-associated transcripts, seemingly indicating that this population might be in the recently antigen-primed states. Such a small population of CD45RA+ CD4+ T cells expressing CD25 appeared to be present in the blood throughout human life. The results suggest that CD4+ T cells with the naive (CD45RA+) phenotype expressing IL-2R alpha-chain (CD25) represent the novel transitional population in the maturation process of naive into memory CD4+ T cells.
Department of Pediatrics, School of Medicine, Kanazawa University, Ishikawa, Japan.
H
H
Kanegane
T
T
Miyawaki
K
K
Kato
T
T
Yokoi
T
T
Uehara
A
A
Yachie
N
N
Taniguchi
D000328:Adult; D000367:Age Factors; D015703:Antigens, CD / Q000032:analysis*; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002469:Cell Separation; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D005434:Flow Cytometry; D015870:Gene Expression; D006649:Histocompatibility Antigens / Q000032:analysis*; D006801:Humans; D007156:Immunologic Memory; D007231:Infant, Newborn; D017493:Leukocyte Common Antigens; D008222:Lymphokines / Q000235:genetics*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D015375:Receptors, Interleukin-2 / Q000032:analysis*; D016176:T-Lymphocyte Subsets / Q000276:immunology*
D015703:Antigens, CD; D006649:Histocompatibility Antigens; D008222:Lymphokines; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; D017493:Leukocyte Common Antigens