Methods of processing marrow samples may affect the frequency of detectable aneuploid cells

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Abstract
Karyotypes were analyzed from 14 patients with myeloproliferative disorders who had marrow samples processed directly and cultured in various ways. Eleven patients had acute nonlymphocytic leukemia (ANLL) or a dysmyelopoietic syndrome. All of these patients were known to have an abnormal karyotype, and in each case, 2 samples of a bone marrow aspirate were available. Five of the 11 patients had essentially the same proportion of abnormal cells in the direct and 24-h samples; in 5 other patients, the percentage of aneuploid cells in the sample cultured for 24 h was higher than that in the direct preparation. A higher percentage of aneuploid cells was observed in the direct preparation in only 1 case. In 3 other cases of ANLL, marrow aspirates were also cultured with methotrexate; only 2 of these had an abnormal clone in any sample. The results of karyotype analysis differed in these 2 patients. The proportion of aneuploid cells was substantially higher in the methotrexate culture than in the 24 h culture in 1 patient; in the other patient, the 24 h culture contained aneuploid cells; the methotrexate culture showed none. Three of the 13 aneuploid patients would have been incorrectly classified as karyotypically normal on the basis of the initial analysis of the direct preparation, since only a single abnormal cell was detected in each case. The karyotypic pattern in untreated patients with ANLL has prognostic significance; therefore, the method of processing marrow aspirates may substantially influence the degree of correlation between the karyotype and survival reported by different laboratories.