Semi-micro adaptation of a 4-day differential staining cytotoxicity (DiSC) assay for determining the in-vitro chemosensitivity of haematological malignancies.

A semi-micro differential staining cytotoxicity (micro-DiSC) assay has been developed to determine the in-vitro chemosensitivity of haematological cancers. The method comprised isolation of leukocytes from blood or bone marrow, drug exposure and culture for 4 days in 1 ml tubes arranged in the microtitre format. Drug-induced tumour cell kill was determined by differential staining of live and dead cells, such that the former could be morphologically identified. Tumour cell viability was calculated by reference to an internal standard of fixed duck red blood cells. Up to 15 drugs at 5-6 concentrations each could be set up at a time in the assay within one hour of receipt of a sample, using only 10(7) viable cells. A result was obtained in 38 of 40 samples received. The assay is of potential use for the routine prediction of clinical response to cytotoxic drugs in haematological cancers and warrants wider investigation.