CD27 down-modulation correlates well with perforin expression in CD8 T cells, but CD45RA expression is more variable.

PBMCs from healthy and HIV-infected donors were costained for CD8, CD27, or CD45RA, and perforin or GzmA. Cells in a CD8⁺lymphocyte gate were analyzed. Typical dot plots are shown for long-term asymptomatic HIV-infected donor CW18 in panel A. The percentages of perforin⁺ and GzmA⁺ CD8 T cells that stain for CD27 or CD45RA for healthy donor and HIV-seropositive samples are depicted by box plots in panel B. In the box plots, the median value is indicated by a white bar, and interquartile differences (25th-75th percentile) by the box. Dotted lines represent 1.5 interquartile differences. There were no outlying data points. Perforin⁺ cells are uniformly CD27⁻ in healthy donors, but a significant proportion of perforin⁺ cells in HIV-infected donors still express CD27.