Separation of lymphocytes and mast cells from the Furth transplantable mast cell tumor in an isokinetic gradient of Ficoll in tissue culture medium.

Cell suspensions of the transplantable Furth murine mast cell tumor were separated both by velocity sedimentation in an isokinetic gradient and by isopyknic sedimentation. Prior to separation, the suspension of tumor cells contained 60.3+/-13.1% (S.D.) malignant mast cells, 9.8+/-10.4% lymphocytes, 4.3+/-2.1% granulocytes, 1.7+/-1.9% macrophages, 0.6+/-0.4% unidentified cells, and 22.8+/-8.5% red blood cells. After either isokinetic or isopyknic sedimentation, more than 97% of the nucleated cells in the purest modal fraction were malignant mast cells. Velocity sedimentation in the isokinetic gradient offered several advantages over isopyknic separation of this tumor; namely, in isokinetic sedimentation, the cells are exposed to a lower centrifugal force for a shorter period of time; a much larger proportion of mast cells were in the highly purified zone of the gradient following velocity sedimentation; and lymphocytes were more highly purified (88.9+/-10.1% of the nucleated cells) following velocity sedimentation. Granulocytes and macrophages were purified more than 8-fold over the nucleated cells in the starting sample suspension. The purified cells from this tumor offer the opportunity to study the interactions between highly purified, easily identified, malignant cells and cells that may participate in the defense of the host against cancer.