Secondary cytokine secretion by stimulated human peripheral blood mononuclear cells. Cells were incubated with chTNT-3, chTNT-3/IL-2 WT, or IL-2 analog fusion proteins in serum-free media. Secreted cytokines were analyzed by indirect ELISA after 1, 3, 5, and 7 days. Results shown are representative for the 2 PBMC donors tested for (A) IL-1β; (B) IFN-γ; and (C) TNF-α.