[Further use of antithymocyte serum]

Antithymocyte serum (ATS) is a kind of hetero-antiserum, many actions of which have been proved since 1974. Recently, we have transplanted several kinds of cell lines, including the diploid cells from human embryo lung (KMB 17,2BS) heteroploid cells (BHK21, FL) and malignant cells (BEL7404, Hela). Our experiments showed that malignant and heteroploid cells could be introduced into new born rats or mice under the effect of ATS and became transplanted tumour. However, in the rats or mice treated with ATS, the diploid cells could produce only necrotic or inflammatory nodules but not transplanted tumors. In recent years, a baby hamster kidney cell line (BHK21) has been applied in transformation assay. However, the experiments show that BHK21 cells, at 237 generations, have already become malignant cells, therefore, it can not be used for transformation assay. For BHK21 cell line, it is better to do the tumorigenicity test or to use earlier cells before the transformation assay. ATS method, used routinely to detect the malignant or normal cell lines, is worth extensive application.