FIG. 2.

CD4⁺ T-cell responses to antigens in uninfected controls, LTNP, and HIV-infected patients with progressive disease who are on or off therapy. A. Frequency and subsets of CD4⁺ T cells producing the cytokine IFN-γ, IL-2, or TNF-α in response to viral antigens or tetanus toxoid. B. Frequency and subsets of CD4⁺ T cells expressing the phenotypic marker CD27, CCR7, or CD45RA. All frequencies have been adjusted for background by subtracting the corresponding subset of the medium control. All frequencies displayed represent median responses.