Growth and spread in nude mice of Epstein-Barr virus transformed B-cells from a chronic lymphocytic leukemia patient.

Subcutaneous inoculation of Epstein-Barr virus (EBV) transformed peripheral blood B-lymphocytes (PBL) from an untreated chronic lymphocytic leukemia (CLL) patient produced progressively growing lethal tumors in 4 of 11 whole body irradiated (440 rads) nude mice. In one tumor bearing mouse there was splenomegaly and generalized enlargement of lymph nodes. Chromosomal analysis and membrane immunofluorescence revealed that cells in all the 4 s.c. tumors and a proportion of cells in the enlarged spleen and lymph nodes had human chromosomes and contained human kappa or lambda chains demonstrating that these were polyclonal human B-cells. Epstein-Barr virus associated nuclear antigen could be detected in 100% of cells in all the 4 EBV transformed B-cell lines in vitro and aliquots of cells from several s.c. tumors and metastatic lesions examined. Successful serial transplantation into irradiated nude mice was possible for at least 3 generations with one of the 4 s.c. tumors. During serial transplantation, spread of tumor cells to the spleen and lymph nodes could be detected in all the 3 passage mice investigated; however, there was no evidence in any mouse of dissemination of tumor cells into the bloodstream or into any organ other than lymph nodes and spleen. s.c. tumors also developed in a proportion of irradiated nude mice after inoculation of cells from two other s.c. tumors and the metastatic spleen and lymph nodes, but all these tumors regressed during the first or second transplant passage. Two % of PBL from the untreated patient and 4% of EBV transformed PBL maintained in vitro were found to have trisomy of chromosome 12 which is the most frequently reported anomaly associated with human CLL B-cells. It is highly probable that the cells with trisomy were derived from the leukemic clone of this patient. Cells with this trisomy predominated in most metastatic sites compared to the parent s.c. tumors. Inoculation of irradiated nude mice with EBV transformed PBL from this patient after chlorambucil therapy (100% metaphase plates with 46,XY,11q+ karyotype) or with EBV transformed PBL from 2 normal adults failed to produce any progressively growing tumor in a total of 12 irradiated animals observed greater than 300 days. Although there are several reports of EBV induced immortalization of CLL B-cells in vitro, we have not seen any previous report on the successful serial transplantation and dissemination of EBV transformed CLL B-cells in nude mice.