Long-term in vitro growth of human T cell clones: can postmitotic 'senescent' cell populations be defined?
The long-term in vitro growth characteristics of peripheral, nonspecifically expanded T cell clones from young (< 30 years old) and old (> 65 years old) Senieur-protocol compatible healthy blood donors were compared. Additionally, T cell clones derived from the sites of autoimmune events were studied. Until the 6th week in culture all clones showed a progressive increase in cell number. CD25 expression and proliferation in response to stimulation with recombinant IL-2 remained stable. Staining of DNA fragments with propidium iodide, however, revealed a small percentage of apoptotic cells. After 7-12 weeks in culture a rapid decrease in cell numbers accompanied by a striking increase in the number of apoptotic cells was noted in all peripheral clones. Although CD25 was still present on almost 100% of the cells, receptor density and proliferative response to IL-2 were greatly reduced. After a maximum of 14 weeks in culture, corresponding to 29 population doublings (PD), all peripheral T cell clones had died. No difference was noted between CD4 and CD8 T cell clones, but clones from old donors tended to have a shorter lifespan and a lower number of PD than clones from young persons (n.s.). Interestingly, T cells from autoimmune lesions had a longer lifespan and a higher number of PD than peripheral T cell clones (p < 0.01). In contrast to peripheral T cell clones, which died almost immediately after reaching the end of their proliferative capacity, a small but stable nondividing cell population could be distinguished in autoimmune clones.(ABSTRACT TRUNCATED AT 250 WORDS)
Immunology Unit, Austrian Academy of Sciences, Innsbruck.
B
B
Grubeck-Loebenstein
H
H
Lechner
K
K
Trieb
D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000473:pathology; D015551:Autoimmunity; D016923:Cell Death / Q000502:physiology; D002455:Cell Division; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology*; D002999:Clone Cells; D004247:DNA / Q000096:biosynthesis; D004261:DNA Replication / Q000502:physiology; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D008938:Mitosis / Q000502:physiology*; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology*
D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D004247:DNA