The leukemia from which the human cell line HL-60 was derived was classified in 1976 as acute progranulocytic leukemia (APL), although it was recognized to show a number of atypical features. In the ensuing 10 years, the concept of APL and its integral association with t(15;17) has evolved, and the concept of APL as a morphologically recognizable entity has become embodied in the term French-American-British classification M3 (FAB-M3). It is now recognized that not every case of leukemia with a high proportion of progranulocytes can be classified as FAB-M3. We reviewed the light and ultrastructural morphology of the original diagnostic material from this case, and we report that the leukemia from which HL-60 was derived does not conform to the currently recognized entity of FAB-M3 and is more appropriately classified as an acute myeloblastic leukemia with maturation, FAB-M2.

Cytogenetic studies (CG) of 475 chronic lymphocytic leukemia (CLL) cases showed trisomy 12 in 6.1% or 26% of patients with abnormal karyotypes. Fluorescence in situ hybridization (FISH) detected trisomy 12 in 35% of 117 CLL patients. Only 34.6% of cases detected by FISH were detected by CG. Twelve patients had low levels of trisomic cells (4% to 11%) relative to clonal B cells (47.5% to 86%), suggestive of clonal evolution. Untreated patients with trisomy 12 were predominantly male (P < .05) and had an increased incidence of splenomegaly (P < .03). Patients with trisomy 12 were more likely to be previously treated and had advanced Binet stage compared with those without trisomy 12. The median survival was shorter in patients with trisomy 12 (7.8 years) and patients with other chromosomal abnormalities without trisomy 12 by FISH (5.5 years) than in patients with diploid karyotypes (14.4 years). The response to fludarabine was similar to that of patients with diploid karyotypes, but there was a trend for earlier disease progression. FISH detected residual disease in all patients with trisomy 12 in complete (n = 6) or partial remission (n = 4). As few as 1 trisomic cell in 5,000 was detected by performing FISH on fluorescence-activated cell sorter-sorted cells. Trisomy 12 was absent in T cells in patients with trisomy 12. We conclude that FISH identifies trisomy 12 approximately 2.6 times more often than CG, readily identifies minimal residual disease, and predicts for a shorter median survival.

We have molecularly cloned the human myeloperoxidase (MPO) gene from the lambda gt11 expression library by screening with an affinity- purified MPO antibody. The cDNA clone of the MPO gene was used to study MPO gene expression in leukemic cells. The amino acid sequence predicted from the nucleotide sequence of the cDNA clone pMP401 matched exactly the 23 amino acid sequence of the NH2-terminal of the 60,000 MPO subunit. We found that MPO cDNA hybridized to a single EcoRI genomic band of 19 kb, indicating that the MPO gene represents a single gene in the human genome. Northern blot analysis of RNA isolated from leukemic cell lines and acute myelogenous leukemia (AML) patients' samples shows that MPO gene expression correlated with myeloid lineage. The intensity of MPO mRNA expression on Northern blot correlated with the level of MPO expression by cytochemical staining. Multiple species of MPO mRNA were found. This indicates that a single MPO gene may encode different RNA species through a mechanism of posttranscriptional processing or that multiple transcriptional start/termination sites exist in the MPO gene.

A complete hematologic remission was achieved in a patient with therapy- related preleukemia and transfusion-dependent pancytopenia after treatment with recombinant human granulocyte-macrophage colony- stimulating factor (GM-CSF). The patient remained in remission for nearly 1 year despite the discontinuation of GM-CSF treatment. Several lines of evidence suggest that normal hematopoiesis was restored after GM-CSF treatment. First, the cytogenetic anomaly, which was present before GM-CSF, completely disappeared after three cycles of treatment. Cytogenetic conversion was documented by conventional karyotypic evaluation of mitotic bone marrow cell preparations as well as by premature chromosome condensation analysis of the nonmitotic cells of bone marrow and peripheral blood. Second, the growth pattern and cycle status of bone marrow granulocyte-macrophage (CFU-GM) and erythroid (BFU-E) progenitor cells were found to be normal during remission. Third, X chromosome-linked restriction fragment length polymorphism- methylation analysis of DNA from mononuclear cells (greater than 80% lymphocytes) and mature myeloid elements showed a polyclonal pattern. These findings suggest that restoration of hematopoiesis in this patient after GM-CSF treatment may have resulted from suppression of the abnormal clone and a selective growth advantage of normal elements.

Previous reports have indicated that mutations of the RAS oncogenes are not associated with the chronic phase of Philadelphia chromosome- positive chronic myelogenous leukemia (Ph1+ CML). However, further studies were needed to determine their association with Ph1- CML and chronic myelomonocytic leukemia (CMML). Therefore, 6 patients with Ph1- CML who were also negative for BCR rearrangements (Ph1-/BCR- CML) and 30 patients with CMML were analyzed for the presence of RAS oncogene point mutations to determine the similarities of these diseases at the molecular level. The assay used the polymerase chain reaction for amplification of the target RAS sequences and panels of specific synthetic oligonucleotide probes for hybridization to wild type and/or mutated sequences. None of the six Ph1-/BCR- CML patients had mutations in the RAS oncogenes, while 17 of 30 (57%) of the CMML patients had RAS oncogene mutations. Eighty percent of the mutations involved substitution of aspartic acid for glycine (G----A) in the 12th or 13th codons of N-ras or K-ras. Furthermore, although not statistically significant, survival studies raise the possibility of shortened survival in patients with RAS oncogene point mutations, with the average survival being 33 months for Ph1-/BCR- CML, 35 months for CMML without point mutations, and 11 months for CMML with RAS mutations. Thus, RAS mutations appear to be associated with CMML and not Ph1-/BCR- chronic phase CML, there is a high propensity for the K-ras or N-ras mutations to involve an G----A substitution in the 12th or 13th codons, and RAS mutations in CMML may relate to prognosis and require further studies.