FIG. 2.

Low-level IFN in primary CD8⁺ cells. (A) Dot plots, gated on lymphocytes, show the profiles of unstimulated peripheral blood mononuclear cells after cell-surface staining with anti-CD8 and intracellular staining with an isotype control antibody (upper panel) or anti-IFN-α (lower panel). (B) Shown are the percentages of CD8⁺ cells staining positive for intracellular IFN-α2 (clone 7N4-1) in 11 human immunodeficiency virus 1 (HIV-1)-infected and 9 uninfected individuals. The Mann–Whitney U test was used to compare the frequencies of IFN⁺ CD8⁺ cells among the 2 groups of individuals. (C) Levels of type I and II IFN transcripts were measured in RNA extracted from unstimulated CD8⁺ cells using quantitative reverse transcriptase (RT)–polymerase chain reaction. Symbols are used to distinguish the transcript levels between the CD8⁺ cells from the 4 study subjects (see legend; uninfected subject, A; HIV-1-infected subjects, B–D).