Characterization of biological activity of anti-CTLA4 neutralizing antibody in CTLA4 cell-based assay using the CTLA4/IL-2 Reporter-Jurkat cells co-cultured with Raji cells/anti-CD3 antibody Dose response of anti-CTLA4 neutralizing antibody in CTLA4/IL-2 Reporter-Jurkat cells. Anti-PD-1 neutralizing antibody (BPS bioscience #71120) is shown as a negative control. FACS analysis of cell surface expression of CTLA4 in CTLA4/IL-2 Reporter-Jurkat cells