Effect of addition of Abs against T-cell growth factors or their receptors on tumor cell proliferation. Tumor cell lines LSA (A), PE-3T (B), EL-4 (C), and P815 (D) were cultured in the presence of MoAbs against IL-2, IL-2R, IL-4, or a combination of anti–IL-2 and anti–IL-4 at 1:4 dilution of purified Abs for 0 to 72 hours. Cells incubated with media alone or with normal rat IgG were used as controls. The cell proliferation was measured by counting the viable cells using trypan-blue dye exclusion. Means of cell numbers from experimental groups and the control ± SEM were plotted.