Detection of Philadelphia chromosome-positive cells from glass slide smears using the polymerase chain reaction

Southern and Northern blot hybridization studies and the polymerase chain reaction (PCR) have been used to analyze the bcr-abl gene complex in chronic myelogenous leukemia (CML). Because fresh or cryopreserved cells may not always be available for molecular analyses, we investigated the possibility of using routinely prepared glass slide smears of blood or bone marrow as our source of cellular material. Cellular RNA was prepared directly from the blood or bone marrow smears using a modified RNA extraction procedure. cDNA was synthesized from RNA and amplified with PCR using bcr and abl-specific primers. Using this procedure, the bcr-abl fusion gene was detected by PCR in 21 of 21 patients with CML. Three patients who had undergone allogenic bone marrow transplantation (BMT) for CML were also studied by PCR. bcr-abl was identified transiently in one patient, persisted in one patient after BMT for 2 years until relapse occurred, and was absent in one patient to 18 months after BMT. We have shown that PCR can detect the bcr-abl gene of CML using material from glass-slide smears. This technique may be useful as a general approach in evaluating archival hematologic specimens for the expression of critical gene products.