Figure 2. IL-12, but not IFN-α, promotes Th1 development in human PBMC cultures.

A, Human PBMCs were stimulated with plate-bound anti-CD3 + anti-CD28 in the presence of IL-2 and the indicated cytokines and/or neutralizing antibodies, where “+” indicates addition of cytokine, and “−” indicates addition of neutralizing anti-cytokine antibody. Parallel cultures were stimulated in the absence (open bars) or presence (closed bars) of neutralizing anti-hIL-4 antibody. B, Human PBMCs were activated with plate-bound anti-CD3 and anti-CD28 in the presence of IL-2 and the indicated cytokines and neutralizing antibodies, where “+” indicates addition of cytokine, “−” indicates addition of neutralizing anti-cytokine antibody, and “o” indicates that the cytokine was not manipulated. On day 3, cells were diluted 1:8 into fresh medium containing IL-2 and rested to day 7. Cells were restimulated for 4 hours in the presence of PMA + ionomycin. Intracellular cytokine staining was performed with antibodies specific for hCD4 and hIFN-γ. Data were gated on live cell populations and expressed as a percentage of CD4⁺/IFN-γ⁺ cells.