TUMOR-CELL KINETICS USING 2 LABELS AND FLOW-CYTOMETRY

A flow cytometry based, single sampling method employing sequential br omodeoxyuridine (BrdUrd) and iododeoxyuridine (IdUrd) labeling with an intervening interval is examined. BrdUrd-specific and nonspecific mon oclonal antibodies and flow cytometry are used to estimate the duratio n of DNA synthesis and the potential doubling time in tumor cell popul ations using a single sampling or biopsy. A correction for labeled, di vided cells allows postlabel incubation intervals to exceed the length of the G2/M phase of the cell cycle. The method yields reliable resul ts when tested in experimental tumor systems in vitro and in situ, as well as in nine human tumors labeled in situ. It uses a somewhat simpl er analysis than the alternative relative movement method, requiring o nly labeling indices, rather than both a labeling index and relative m ovement, but does require the administration of two, rather than one, label. It provides an independent verification of and a useful single sampling alternative to the relative movement method for the estimatio n of the length of S phase and, from this, the potential doubling time in experimental or clinical human tumors. (C) 1994 Wiley-Liss, Inc.