recombinant human IL-2 (HZ-1015) stimulates dose-dependent proliferation of the CTLL-2 (mouse cytotoxic T) cell line. Viable cell number was quantitatively assessed by Prestoblue Cell Viability Reagent. CTLL-2 cells were starved for 5 hours before treatment with increasing concentrations of GMP recombinant human IL-2 for 48 hours. The EC50 was determined using a 4-parameter non-linear regression model. The EC50 values range from 0.05-0.35 ng/mL.