Relationship between karyotype of tissue culture lines and tumorigenicity in nude mice.

There are many factors, other than the absence of an immune response, that are responsible for the successful transplantation of xenografts to nude mice. We have defined, in this study, the relationship between karyotype and transplantability of xenografts into nude mice, using a library of 85 tumor and normal tissue culture lines. Each of these lines had been previously passaged in tissue culture for more than 10 generations. 53 of these 85 lines were classified as diploid, whereas 32 lines were classified as heteroploid. These tissue culture lines were transplanted to groups of 4-10 unmanipulated and antilymphocyte serum (ALS)-treated nude mice and serially monitored for 12 weeks. Only 19% of the diploid lines were successfully transplanted into unmanipulated nude mice, and only 30% were successfully transplanted into ALS-treated nude mice. In comparison, 50% of the heteroploid lines were successfully grafted into unmanipulated nude mice, and a total of 60% were successfully transplanted into ALS-treated nude ice. 12 of the 53 diploid lines can be classified as being pseudodiploid on the basis of rearranged chromosomes or other minor karyotype anomalies. 8 of these 12 pseudodiploid lines were successfully transplanted into nude mice, further strengthening the relationship between abnormal karyotype and transplantability. Tumor karyotype is an additional parameter which should be added to the variables involved in the successful transplantation of tumors to nude mice.