[Application of flow cytometry to the chemosensitivity test by the BrdU labeling method; a preliminary report]

In the present paper we discussed whether a new method of chemosensitivity test could be developed using FCM (flow cytometry) and applied to malignant brain tumor cells labelled with BrdU monoclonal antibody. For this purpose, a basic study was performed with an ACNU-resistant C6 cell line and a sensitive one to see if this method was able to detect the difference of sensitivity between these cell lines. After 8 hours treatment with ACNU (concentration: 10 micrograms/ml), ACNU-sensitive cells revealed on LI (labeling index) of 46%, which was very high in comparison with controls, whereas the figure for ACNU-resistant cells was 34%, which was almost the same LI value as non-treated control cells. This means that change in the BrdU labeling index after chemotherapy in vitro can be used to determine the chemosensitivity of malignant brain tumors when FCM is employed. Furthermore, this method can detect the chemosensitivity of each clone in polyclonal human tumors which is impossible for the HCSA method, since the latter can reveal only the chemosensitivity as a whole in such tumors.