The proliferation of human melanoma cells (MeWo) in vitro was studied
with a number of different techniques. In particular, we compared the
expression of PCNA and the Ki-67 antigen on the one hand with BrdU pul
se and continuous labelling on the other. Two-dimensional flow cytomet
ry (with DNA content as a second parameter) was employed to discrimina
te between cycling and non-cycling cells as well as cells in the G(1),
S and G(2) phases of the cycle. Cell cultures in different stages of
growth were analyzed. We found that the percentage of anti-PCNA and Ki
-67 positive cells agreed very well with the BrdU pulse and continuous
labelling index, respectively. Our data further support the assumptio
n that under certain conditions PCNA is a marker of S-phase cells, whe
reas Ki-67 can be used to quantify the growth fraction. Possible pitfa
lls of the techniques are discussed.