FIG. 7.

Conditioned supernatant from on-therapy PBMC rescues the proliferation of off-therapy PBMC, and depletion of IL-2 from the supernatant abrogates this effect. A. Proliferation of IL-2-dependent CTLL-2 cells to medium containing known concentrations of IL-2. Medium was treated with control antibody or anti-IL-2 antibody, followed by depletion of antigen-antibody complexes with protein G-agarose beads. B. Proliferation of CTLL-2 cells to untreated medium and IL-2-depleted medium that have been spiked with known amounts of IL-2. C. CD4⁺ T-cell proliferation to an HIV Gag peptide pool from a representative patient undergoing treatment interruption. D. Proliferation of off-therapy cells to HIV Gag peptides in the presence of conditioned supernatant by on-therapy PBMC exposed to HIV Gag peptides. Conditioned supernatants were treated with control antibody or anti-IL-2 antibody as described in the text. Low concentration, 750,000 off-therapy cells with 250 μl conditioned supernatant; high concentration, 250,000 off-therapy cells with 750 μl conditioned supernatant. E. Summary of data for off-therapy CD4⁺ T-cell proliferation to Gag peptides in patients undergoing treatment interruption. Off-therapy cells were cultured alone or in the presence of low or high concentrations of conditioned supernatant treated with a control antibody or anti-IL-2 antibody.