The decline in interferon-γ (IFN-γ) production with culture age . Reproduced with permission from Blackwell Publishing. Long-term HIV-specific cultures were established by repeated stimulation of CD8 T-cells from HLA-A2+ HIV-infected persons with the appropriate gag, pol and env peptides. Early passage (5 population doublings, PD 5) and late passage (PD 25) cultures from three different donors were assessed for intracellular IFN-γ using flow cytometry.
Aspinall et al. Immunity & Ageing 2007 4:9 doi:10.1186/1742-4933-4-9