Different binding activities between rATG and hATG. (A) Different binding of rATG and hATG to lymphocytes evaluated by intensity of antirabbit IgG-FITC and antihorse IgG-FITC. Untreated PBMCs were used as a negative control. Data are derived from lymphocyte gate. Results are representative of 3 independent experiments. (B) Blocking capacity for known cell surface antigens, CD3, TCRαβ, CD4, and CD28, of lymphocytes with rATG or hATG. Data are derived from the lymphocyte gate; untreated PBMCs stained with corresponding surface antigens were used as a positive control. Mouse IgG conjugated with the corresponding fluorochrome was used as an isotype control. Results show representative of 3 independent experiments. (C) Different activation states of CD4⁺ T cells induced with rATG or hATG. GITR and CTLA-4 were used to evaluate activation. Untreated PBMCs were used as a control; mouse IgG conjugated with PE was used as an isotype control; results are representative of 3 independent experiments.