Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Growth curve of a CD4 T cell clone originating from an 85-year-old donor. Cells were counted every week and subcultured at a standard concentration in fresh medium with new irradiated feeder cells. The estimated number of population doublings (PD) is given at each time point
