HIV-specific CD45RA⁺ CD8⁺ T cells are able to proliferate and to acquire cytotoxic potential after culture. CD45RA⁺ and CD45RO⁺ fractions were obtained after magnetic separation and cultured with the appropriate peptide during 6 days. (A) A representative dot plot obtained after CFSE staining and culture of each fraction. (B) The fold increase of HIV-specific CD8⁺ T cells was calculated for each fraction. (C) Perforin expression by HIV-specific CD8⁺ T cells was measured before (white plots) and after (black plots) culture of the isolated CD45RO⁺ and CD45RA⁺ subsets. The percentage of positive cells is represented for each subset on day 0 and day 6. Statistical differences between groups are indicated above the bars.