Human CD8(+) T cells expressing HLA-DR and CD28 show telomerase activity and are distinct from cytolytic effector T cells.
Cycling lymphocytes may express the enzyme telomerase which is involved in maintenance of telomere length and cell proliferation potential. In CD8(+) T cells freshly isolated from peripheral blood, we found that in vivo cycling cells expressed HLA-DR. Furthermore, CD28-positive cells are known to have longer telomeres than CD28-negative T cells. Therefore we used HLA-DR- and CD28-specific antibodies to sort CD8(+) T cells and measure telomerase activity ex vivo. Relatively high levels of telomerase activity were found in HLA-DR/CD28 double-positive cells. In contrast, HLA-DR-negative and CD28-negative cells had almost no telomerase activity. In summary, HLA-DR expression correlates with proliferation, and CD28 expression with proliferative potential. We have previously identified that ex vivo cytolytic CD8(+) T cells are CD56 (NCAM) positive. Here we show that HLA-DR(+) cells were rarely CD56(+) and vice versa. This demonstrates that telomerase-expressing and cytolytic CD8(+) T cells can be separated on the basis of the cell surface markers HLA-DR and CD56. Thus, activated CD8(+) T cells specialize and exert distinct functions correlating with surface molecule expression.
Speiser
D E
DE
Division of Clinical Onco-Immunology, Ludwig Institute for Cancer Research, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. daniel-speiser@hospvd.ch
Migliaccio
M
M
Pittet
M J
MJ
Valmori
D
D
Liénard
D
D
Lejeune
F
F
Reichenbach
P
P
Guillaume
P
P
Lüscher
I
I
Cerottini
J C
JC
Romero
P
P
D018106:CD28 Antigens / Q000032:analysis*; D019002:CD56 Antigen / Q000032:analysis; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry* / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D006684:HLA-DR Antigens / Q000032:analysis*; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008213:Lymphocyte Activation; D019098:Telomerase / Q000378:metabolism*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000032:analysis
D018106:CD28 Antigens; D019002:CD56 Antigen; D006684:HLA-DR Antigens; D019394:Ki-67 Antigen; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D019098:Telomerase