Caution on the use of lymphocytes as standards in the flow cytometric analysis of cultured cells.

Flow cytometry was used to compare the fluorescence intensity of the G0/G1 peak of a diploid (WI-38), a hypodiploid (C4I) and a heteroploid (KB) human cell line with that of nonstimulated human lymphocytes. With all three cultured cells the fluorescence intensity was substantially higher than that of lymphocytes. These results, obtained with three different DNA-intercalating fluorochromes, suggest that lymphocytes may not be the standard of choice for flow cytometric studies of the DNA distribution in human cell cultures and that diploid cells such as WI-38 may be more appropriate for this purpose.