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Quantitative determination of the hybrid Bcr‐Abl RNA in patients with chronic myelogenous leukaemia under interferon therapy
Author(s) -
Malinge MarieClaire,
Mahon Francois Xavier,
Delfau Marie Hélène,
Daheron Laurence,
Kitzis Alain,
Guilhot François,
Tanzer Joseph,
Grandchamp Bernard
Publication year - 1992
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1992.tb06947.x
Subject(s) - abl , serial dilution , breakpoint cluster region , chronic myelogenous leukemia , rna , k562 cells , philadelphia chromosome , biology , reverse transcriptase , messenger rna , minimal residual disease , real time polymerase chain reaction , microbiology and biotechnology , leukemia , medicine , immunology , tyrosine kinase , pathology , gene , genetics , signal transduction , chromosomal translocation , alternative medicine
In vitro amplification of the Bcr‐Abl cDNA has been widely used to assess for the presence of minimal residual disease in patients with chronic myelogenous leukaemia (CML) presenting with complete clinical and cytogenetic remission. However, the level of sensitivity achieved in different laboratories remains largely unknown. Moreover, the results are usually expressed as positive or negative, making a precise follow‐up of the patients difficult. In an attempt to overcome these limitations, we devised a quantitative method to measure the amount of Bcr‐Abl mRNA in clinical samples. This methodology involves a single reverse transcription step, followed by separate amplification of Bcr‐Abl and total Abl mRNA. These two amplifications are performed in the presence of different dilutions of a same internal standard. This standard consists of Bcr‐Abl sequences with an eight bases deletion in exon 2 of Abl. One of the primers used in each separate reaction is labelled with fluorescein. Following amplification, PCR products derived from cellular RNA and those from the internal standard are separated and their relative fluorescence is determined using a laser fluorescent DNA sequencer (ALF. Pharmacia). The number of Bcr‐Abl and total Abl mRNA molecules initially present in each sample is then calculated. The accuracy and reproducibility of this method was assessed by studying serial dilutions of K562 RNA into normal RNA. Blood samples from 10 patients in cytogenetic remission under interferon therapy were studied. Only one sample was found negative while the others contained between 0.05 and 17 hybrid Bcr‐Abl mRNA molecules per 1000 molecules of Abl mRNA. These results suggest that a variable number of malignant cells are present in the majority of CML patients in cytogenetic remission following interferon therapy.