The influence of sample source and cell concentration on the in vitro chemosensitivity of haematological tumours.

The Differential Staining Cytotoxicity (DiSC) assay has been used to study the effects of sample source and cell concentration on the in vitro chemosensitivity of haematological malignancies. The chemosensitivity of blood and bone marrow samples was significantly associated (P less than 0.001) in 12 cases where both were tested simultaneously. In 8 of the cases, where the in vitro result could be compared with clinical response, the in vitro and in vivo chemosensitivity was in agreement in 7, for both blood and bone marrow samples. The in vitro chemosensitivity of chronic lymphocytic leukaemia blood lymphocytes was dependent on the cell concentration for 4 out of 5 drugs tested. A five fold reduction in cell number resulted in a significantly greater cell kill with 4-hydroperoxycyclophosphamide, a greater cell kill (not significant) with chlorambucil and adriamycin, and a significantly lower cell kill with prednisolone. The cell concentration did not affect vincristine cytotoxicity. These results suggest that sample source is not an important consideration for the in vitro chemosensitivity of leukaemias, but that the cell concentration tested should not be varied from assay to assay if the results are to be used for comparative purposes.