Decline in CD28+ T cells in centenarians and in long-term T cell cultures: a possible cause for both in vivo and in vitro immunosenescence

Exp Gerontol. Nov-Dec 1994;29(6):601-9. doi: 10.1016/0531-5565(94)90073-6.


The dramatic decline in immune function with age, especially in T cell proliferative activity, has been documented extensively in experimental animal models and in clinical studies of the elderly. A similar proliferative decline is also seen in long-term T lymphocyte cultures used to study in vitro cellular senescence. We have compared the peripheral blood T lymphocytes of centenarians and younger controls for the cell surface expression of CD28, a costimulatory molecule that is required for optimal activation and proliferation following engagement of the T cell receptor. Our analysis shows a significant decrease (p < 0.001) in the percentage of T cells expressing CD28 in the elderly cohort, with values ranging from 44% to 90%, as compared to the mean control value of 91%. The decline in the percentage of CD28+ T cells correlates with a reduction in the CD4/CD8 ratio (r2 = 0.695, p < 0.0001). Concommitantly, experiments using an in vitro T cell culture system showed a progressive loss of CD28 expression with culture "age." The concordance of proliferative decline and loss of CD28 in the centenarians and in the in vitro cultures suggest that a Hayflick phenomenon may operate in vivo leading to immunosenescence.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • CD28 Antigens / blood*
  • Case-Control Studies
  • Cells, Cultured
  • Cellular Senescence / immunology
  • Humans
  • Linear Models
  • Lymphocyte Count
  • Middle Aged
  • T-Lymphocyte Subsets
  • T-Lymphocytes / immunology*


  • CD28 Antigens