Bcr‐abl protein detection in peripheral blood mononuclear cells for follow‐up of chronic myelogenous leukaemia patients

Abstract

We have assessed the value of p210 protein detection in peripheral blood cells for follow‐up of chronic myelogenous leukaemia (CML) patients. Quantification was achieved by comparing the relative intensities of the p210 bands with those of the normal abl protein (p145). Serial dilution of Ph‐positive K562 cells with Ph‐negative HL60 or KG1 cells revealed a linear correlation between the p210/p145 ratio and the number of Ph‐positive cells (r = 0.998; p < 0.001) with a sensitivity of detecting less than 1% Ph‐positive cells in 5 times 106 cells. Ninety‐six consecutive patients were enrolled in the study and a total of 155 Western blot analyses have been performed and compared to chromosomal analyses of bone marrow. Parallel RT–PCR analyses have been performed on 99 occasions. All patients with positive cytogenetic findings also probed positive for p210. In 23 instances p210 was detectable despite negative chromosomal analysis. In 16 samples these results were confirmed by RT–PCR. In patients with partial cytogenetic remission (n = 26) the results of the p210 assay correlated significantly with the percentage of Ph‐positive metaphases (r = 0.69; p < 0.001). In conclusion, monitoring of CML patients by quantification of the bcr‐abl protein is a feasible and sensitive alternative to chromosomal analysis of bone marrow.

High frequency of the JAK2 V617F mutation in patients with thrombocytosis (platelet count > 600 × 109/L) and ringed sideroblasts more than 15% considered as MDS/MPD, unclassifiable

“…We wish to confirm recent reports showing that JAK2 V617F [1][2][3][4][5] is commonly detectable in patients with thrombocytosis who also have ringed sideroblasts in their bone marrow. [6][7][8][9] For such patients, the WHO classification provides the category of "myelodysplastic/myeloproliferative disease, unclassifiable," including a subtype of refractory anemia with ringed sideroblasts associated with marked thrombocytosis (RARS-T), 10 which requires at least 15% ringed sideroblasts in the marrow and a platelet count of more than 600 ϫ 10 9 /L.…”

“…It has been known since 1987 2 that such lysis of CML mononuclear cells (MNCs) releases a degradative activity that very rapidly and selectively destroys p210 BCR-ABL1 and c-ABL but does not degrade other proteins. 3 This activity has been reported to be primarily restricted to the mature cell compartments, [2][3][4] hence its influence is commensurately greater in MNC lysates. It is entirely predictable therefore that Copland et al 1 could not recover a p210 BCR-ABL1 signal or a 210-kDa phosphotyrosine signal from a CML MNC blot and that the signal recovered is greater from CD34 ϩ CD38 Ϫ cells than CD34 ϩ cells.…”