Validation of Two Evaluation Methods for Chemical Specific Humoral Immunotoxicity in Rats

Objective To establish a specific humoral immunotoxicity model in rats orally exposed to cyclophosphamide for 28 days and to validate the assays of antibody plaque-forming cells(PFCs)and serum hemolysin concentration(HC_(50)).Methods 40 Male Wistar rats with body weight of 180~(220 g) were randomly divided into control group and groups of 5,10,(20 mg/kg) cyclophosphamide(known as suppressive immunotoxicity)with 10 rats in each group.The rats were orally exposed to cyclophosphamide once a day successively for 28 days.The rats in the control group received normal saline.At the 24~(th) days of exposure,the rats received(1 ml) of 10% sheep red blood cells(SRBCs)by i.p.injection.24 hours after the end of 28 days exposure,the rats were decapitated and their spleens were excised.The spleen single cell suspension was prepared for PFCs assay;at the same time,the blood was collected and serum was prepared for HC_(50) assay.Results The PFCs in groups of 5,10 and(20 mg/kg) cyclophosphamide(respectively 159.6±91.8,93.6±14.8,39.8±11.0)and HC_(50) in groups of 5,10 and 20 mg/kg cyclophosphamide(respectively 125.6±38.5,36.4±5.9,1.5±0.3)decreased significantly compared with those of the control group(PFCs 355.0±96.3 and HC_(50) 283.1±96.3),P0.05.Conclusions The results validate the PFCs assay and the HC_(50) assay,which may provide a reference for establishing the immunotoxicity evaluation methods in China.