Metrizamide gradient purification of mouse tumor cells.

A one-step isopycnic density gradient centrifugation procedure is described for purification of highly viable and homogeneous tumor cells from a variety of solid mouse tumors. Mechanically suspended cells are layered onto preformed continuous gradients of medium 199-buffered 7--33% metrizamide (density range 1.05--1.20 g/cu. cm) isoosmotic with mouse plasma and centrifuged for 30 min. Large numbers of tumor cells, generally 85--95% viable and free from 80--95% of contaminating host lymphoid and phagocytic cells and erythrocytes, were consistently recovered from fractionated thymomas, melanomas, and fibrosarcomas. By a variety of criteria, cell surface and other biological properties of gradient-purified tumor cells were normal.