The Amplification of the Wilms Tumor Gene (wt-1) mRNA Using the Polymerase Chain Reaction Technique (PCR) May Enable Sensitive Detection of Small Blast Populations in AML

Leukemic cells from 52 patients with AML were examined for the expression of wt-1 mRNA. Blast cells were isolated from bone marrow or peripheral blood. Total RNA was extracted and wt-1 transcription was studied via RT-PCR. Mononuclear cells and bone marrow from healthy persons were used as controls. Cell surface antigens were determined using FACS-analysis. In dilution experiments the detection limit was assessed as 1 out of 10000 cells. Wilms’ tumor mRNA was detectable in 41 out of 52 cases of AML (79%). None of the 13 controls expressed wt-1. After chemotherapy, six out of eleven patients in complete remission (CR) lost wt-1 expression completely. The remaining five patients expressed wt-1 mRNA at the same or a lower level. The significance of wt-1 persistance for desease free survival will have to be defined.