ABSTRACT
PURPOSE: The purpose of the present study is to determine the relation between in vitro resistance to 9 drugs, measured with colorimetric methylthiazol tetrazolium(MTT) assay and prognostic factors. METHODS: Thirty children with leukemia were evaluated at the pediatric department of Dongsan Medical Center. All samples tested with the MTT assay contained 80% or more leukemic cells, which were isolated by Ficoll density gradient centrifugation, and were incubated with 9 drugs for 4 days. The optical density(OD) of the wells was measured with microplate spectrophotometer. Leukemic cell survival(LCS) was calculated by OD treated well/OD control wellsx100(%). LD50 was calculated from the dose-response curve and used as a measure of resistance. RESULTS: Among the 30 children with leukemia, 16 were ALL, 14 were AML. Seventeen boys and thirteen girls ranged in age from 9 months to 16 years. Comparing LD50 values according to leukemic type, AML revealed relatively high LD50 values for all drugs, except VCR. But there were no significant differences between ALL and AML(P>0.05). Male showed high LD50 values for ASP, DET, ARA-C, VP16, ADR and 6TG. Age10 years children showed high LD50 values for all drugs, except 6TG. Patients with a leukocyte count>100,000/mm3 at diagnosis showed high LD50 values for VCR, ASP, DET, MTX, ARA-C, ADR, and 6TG. Patients with normal chromosome showed higher LD50 values. CONCLUSION: Our study showed higher LD50 values at AML, male, ageyears old, leukocyte count>100,000/mm3, and normal karyotype. The MTT test may contribute to the selection of effective chemotherapeutic agent for children with acute leukemia.