A rapid method for the isolation of metastasizing tumour cells from internal organs with the help of isopycnic density-gradient centrifugation in Percoll.

Metastasizing tumour cells from a DBA/2 mouse T-cell lymphoma could be separated from the invaded tissue by isopycnic centrifugation in continuous Percoll density gradients. The metastasizing tumour cells from spleen, liver and lung, derived from a cloned lymphoma-cell line, showed a buoyant density in Percoll of 1.060 +/- 0.010. They could be separated from the host tissue, which had a higher buoyant density in the case of the spleen cells or a lower density in the case of the dead liver or lung tissue. The separated tumour cells as removed from the gradients were viable, and could be analysed by in vitro and in vivo assays. The separation procedure did not affect the expression by the tumour cells of TATAs and H-2 antigens. Furthermore, the method seemed to be applicable to the separation of human tumour cells from mononuclear cells prepared from blood samples of tumour patients by Ficoll centrifugation.