Human CD8(+) T cells expressing HLA-DR and CD28 show telomerase activity and are distinct from cytolytic effector T cells

Eur J Immunol. 2001 Feb;31(2):459-66. doi: 10.1002/1521-4141(200102)31:2<459::aid-immu459>;2-y.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CD28 Antigens / analysis*
  • CD56 Antigen / analysis
  • CD8-Positive T-Lymphocytes / chemistry*
  • CD8-Positive T-Lymphocytes / immunology
  • Cytotoxicity, Immunologic*
  • HLA-DR Antigens / analysis*
  • Humans
  • Ki-67 Antigen / analysis
  • Lymphocyte Activation
  • Telomerase / metabolism*
  • Tumor Necrosis Factor Receptor Superfamily, Member 7 / analysis


  • CD28 Antigens
  • CD56 Antigen
  • HLA-DR Antigens
  • Ki-67 Antigen
  • Tumor Necrosis Factor Receptor Superfamily, Member 7
  • Telomerase