FOLR1 and cancer: ADCC of FRα-expressing IGROV1 cancer cells by human peripheral blood mononuclear cells (PBMCs) mediated by low concentrations of MOv18 IgE below or at the EC50 (0.2 or 0.6 μg/ml), were significantly-reduced by high (20 ng/ml), but not by low (4 ng/ml), recombinant FRα concentrations (≥20 ng/ml being the serum concentration measured in the top 8% of our patients) (Fig. 6c).