Objective To compare the in vitro activity of anti-human T lymphocyte porcine immunoglobulin(P-ATG)prepared by Cohn ethanol fractionation and ammonium sulphate precipitation,commercial rabbit anti-human thymocyte immunoglobulin(trade name:Thymoglobuline),and anti-human T lymphocyte rabbit immunoglobulin(trade name:Grafalon)so as to evaluate the properties of P-ATG prepared by two processes.Methods The four products were detected for the antibody-dependent cell-mediated cytotoxicity(ADCC)by lactate dehydrogenase(LDH)method,measured for the complement dependent cytotoxicity(CDC)by CCK-8 assay,and detected for the affinity for binding with different T cell antigens(CD3,CD4,CD8)by double immunofluorescence staining method.Results Among the four products,only Thymoglobuline at the high concentration(1 mg/mL)had a weak ADCC effect on human peripheral blood mononuclear cell(PBMC).All products could induce the CDC effect in human PBMC in a dose-dependent manner,among which the effect of Thymoglobuline was higher than that of P-ATG or Grafalon preared by two processes,about 3 to 4 times,and the effect of Grafalon was comparable to that of P-ATG.In the proportion of four products binding with T cell surface antigens CD3 and CD4 was similar,However the proportion of Thymoglobuline and Grafalon binding with CD8 antigen was slightly lower than that of P-ATG.Conclusion The in vitro activity of the P-ATG prepared by Cohn ethanol fractionation and ammonium sulphate precipitation was in good agreement,and was not lower than that of imported products at the clinical dose.