IL-2 antagonistic/agonistic biological activities of the recombinant chimeric protein. Panel A: Antagonistic/agonistic biological activities. The figure shows plots of a representative CTLL-2 proliferative assay showing the OD of tested samples in each of the evaluated serial dilutions. The IL-2 used for the experiments is the IL-2 international standard (ST-IL-22010397, 880 000 UI/mL). The arrow shows the OD of IL-2 dilution to test in the presence of serial dilutions of recombinant protein. Panel B: Stimulation of T cells proliferation by TH1 antagonist. Bar 1: 2.8 ng/ml of IL-2 (dilution 1:40000), bar 2: 1.5 μg/ml of AnTH1, bar 3: culture medium without IL-2.