J D Rowley — Page 20 | Search PubMed

PubMedDate not supplied

Evaluation of techniques for increasing mitotic yield and chromosome length in leukemic cells.

Previously reported techniques for the culture of bone marrow and unstimulated peripheral blood for cytogenetic analysis were evaluated in patients with acute myelogenous leukemia (AML) or chronic myelogenous leukemia (CML). Samples were treated in the following manner: (1) cold synchronization (exposure to 4 C for eight hours, then incubation at 37 C for 14.5 hours [CML] or 16.5 hours [AML]); (2) cold synchronization plus Hoechst 33258 (as first treatment, with Hoechst 33258 added to a final concentration of 50 micrograms/ml for the last five hours of incubation; (3) methotrexate synchronization (methotrexate added to a final concentration of 10(-7) M, incubation at 37 C for 17 hours, then washing of cells and addition of thymidine to a final concentration of 10(-5) M for an additional 5 hours 15 minutes of incubation); and (4) controls (untreated, incubation at 37 C). All cultures were harvested simultaneously in the usual manner. Our results suggest that cold synchronization provides improvement in mitotic yield and chromosome length as well as in chromosomal morphology, as compared to the results obtained with cold synchronization plus addition of the fluorochrome Hoechst 33258, with methotrexate synchronization or with standard direct culture techniques. Cold synchronization can readily be applied to the routine laboratory culture of hematologic cells for cytogenetic analysis.

Bone Marrow↗

PubMedDate not supplied

Chromosome abnormalities in leukemia and lymphoma.

Nonrandom chromosome changes have been identified in a number of malignant human tumors. The leukemias are among the best studied malignant cells and they provide the largest body of relevant cytogenetic data. In chronic myeloid leukemia, a reasonably consistent translocation [t(9;22) (q34;q11)] is observed in 93 percent of all Ph1 positive patients. In the other patients, translocations are either two-way, involving No. 22 with some other chromosome or complex translocations involving Nos. 9 and 22 and another chromosome. In acute nonlymphocytic leukemia, two translocations are each specifically associated with leukemic cells arrested at two different stages of maturation. One of these, t(8;21)(q22;q22), is found mainly in patients with acute myeloblastic leukemia with maturation (AML-M2). The other, t(15;17)(q22?;q21?), is seen only in patients with acute promyelocytic leukemia (APL-M3). Various translocations have been observed in B-cell acute lymphoblastic leukemia or in Burkitt lymphoma. The most common is t(8;14)(q24;q32), but variants of this, namely t(2;8)(p13?;q24) and t(8;22)(q24;q11), have also been observed; in all of these, the consistent change involves 8q24. The various immunoglobulin loci are located on chromosomes 2, 14, and 22 in the same chromosome band affected by the translocations in B-cell leukemia. These translocations may occur randomly. If a specific translocation provides a particular cell type with a growth advantage, then selection could act to cause the proliferation of this aneuploid cell line vis-a-vis cells with a normal karyotype. In this view, the chromosome change could be the fundamental event leading to the leukemic transformation of an otherwise normal cell. The challenge for the future is to define the genes located at the sites of consistent translocations in myeloid leukemias and to determine the alterations in gene function that are associated with the translocation.

B-Lymphocytes↗