DETECTION OF BCR ABL MESSENGER-RNA IN STAINED BONE-MARROW SMEARS/

We describe the polymerase chain reaction (PCR) method using stained h one marrow smears as sources of RNA. The amount of extractable RNA dec reased during the process of making and staining bone marrow smears. T he sensitivity of the reverse transcriptase-based polymerase chain rea ction (RT-PCR) method for detecting target mRNA-positive cells in 5 x 10(5) suspended cells and stained bone marrow smears were 1 : 10(5) an d 1 : 5000, when we used K562 cells. The bone marrow smears of 21 pati ents with chronic myelogenous leukemia (CML) were examined using this method. We extracted RNA from stained specimens stored at room tempera ture for 5-14 years. Twelve of 21 (57%) smears showed positive results for bcr/abl. The carrier RNA improved the recovery when added at the step of RNA extraction. These data indicate that mRNA is present in st ained bone marrow smears for at least 14 years and that the sensitivit y of RT-PCR is adequate for molecular analysis.