Heterogeneity of lineage involvement by trisomy 8 in myelodysplastic syndrome. A multiparameter analysis combining conventional cytogenetics, DNA in situ hybridization, and bone marrow culture studies.

To better understand the role of trisomy 8 in myelodysplastic syndrome (MDS), we performed a multiparameter analysis combining conventional chromosome studies (CCS), fluorescence in situ hybridization (FISH), and bone marrow (BM) culture studies in two patients with MDS evolving into acute myeloid leukemia (AML). A mosaicism of a cytogenetically normal clone and a clone with trisomy 8 was detected in both patients throughout the course of the disease, a finding confirmed by FISH on BM cells. The relative size of the trisomic clone increased from 52% to 71% (p < 0.0001) and from 53% to 69% (p = 0.001) of all BM cells at the time of the leukemic switch in patients 1 and 2, respectively. Combined FISH and immunophenotyping of BM cells showed involvement of the granulomonocytic lineage in patient 1 and involvement of erythroid cells as well as of the granulomonocytic lineage in patient 2. Only disomic lymphocytes were detected in both patients. FISH on single hemopoietic colonies grown in semisolid media detected trisomic CFU-GM and disomic BFU-E in patient 1, whereas a proportion of CFU-GM and BFU-E deriving from the trisomic clone was detected in patient 2. However, the percent of trisomic colonies was lower than the percent of involved granulomonocyte precursors and involved erythroblasts, as detected by combined FISH and immunophenotyping on fresh BM samples. We have thus shown heterogeneity of lineage involvement by trisomy 8 in MDS undergoing transformation into AML. Although preferential growth of disomic clones may occur in vitro, the finding of an increased size of the trisomic clone at the time of leukemic switch suggests that these cells had proliferative advantage in vivo over cells without trisomy 8.

Involvement of erythrocytic and granulomonocytic lineages by trisomy 11 in two cases of acute myelomonocytic leukemia with trilineage myelodysplasia. An interphase cytogenetic study.

To study the cytologic profile and lineage involvement in acute myeloid leukemia (AML) with trisomy 11, cytologic, cytogenetic, and interphase cytogenetic studies were performed at presentation in two cases of acute myelomonocytic leukemia (AML-M4). Patient 1 had +11 as the sole chromosome aberration in 16/20 karyotypes whereas two related clones with +11 in all abnormal metaphases (14/18) were detected in patient 2. A proportion of interphase cells with three signals, comparable to the proportion of abnormal metaphases, was detected by fluorescent in situ hybridization (FISH) in these patients. Morphologic aberrations of the nonblast cell population affecting multiple cell lineages, along with a circulating minor megakaryoblastic component, were observed at diagnosis in both patients. By separation of bone marrow cells over a density gradient of Percoll two cell fractions were obtained, the former containing more than 80% erythroid precursors (collected at a density of 1065-1075 mg/ml), the latter containing more than 78% blast cells plus granulomonocytic precursors (collected at a density of 1060-1055 mg/ml). FISH documented the presence of a majority of interphase nuclei with three signals in the erythroblast-enriched cell fraction and in the blast-enriched cell fraction. It is concluded that cytologic features, as well as interphase cytogenetic findings on enriched cell fractions, suggest the occurrence of multipotent stem cell involvement in AML-M4 with +11.

Morphologic, immunologic and cytogenetic studies in acute myeloid leukemia following occupational exposure to pesticides and organic solvents.

In order to analyze the correlation between environmental exposure and the clinicopathological picture in acute myeloid leukemia (AML), cytogenetic, cyto-immunologic and clinical studies were performed in 70 newly diagnosed AML patients, 30 of which were anamnestically exposed to pesticides (21 cases) or to organic solvents (9 cases). Clonal chromosome aberrations, with involvement of chromosome 5 and/or 7 were more frequently encountered among exposed patients. While the classical t(15;17), t(8;21) and t(9;11) were detected more frequently among non-exposed patients, other recurring chromosome changes in the exposed group were: rearrangements leading to total or partial monosomy 17p (5 cases), structural aberrations involving the band 16q22 (4 cases), trisomy 11q (2 cases), breaks involving bands 6p23, 7p14, 11q13 (2 cases each). Cytologically, trilineage myelodysplasia was observed in 21 exposed patients, whereas morphologic aberrations of the non-blast cell population were confined to a minority of cells in most patients non-exposed. Immunologic studies revealed positivity for the CD34 stem cell marker in 80% exposed patients vs 22% in the non-exposed group. Conventional chemotherapy achieved complete remission in 3/21 patients exposed and in 16/32 patients non-exposed. Median survival was 2 months in the former group and 9 months in the latter group. These findings show that AML following occupational exposure to pesticides and organic solvents may represent a distinct cytogenetic and clinicopathological entity.

A new chromosomal breakpoint in Ph positive, bcr negative chronic myelogenous leukemia. Report of a case.

We report a new case of Ph positive chronic myeloid leukemia (CML) without the classical rearrangement in Mbcr. By Southern blot analysis the molecular breakpoint was mapped 3 to 8 kb upstream of Mbcr. This region has not been shown to be rearranged in any other described case of CML. We did not detect any specific abnormal BCR-ABL transcript even with the use of the very sensitive RNA-PCR technique.

Non-radioactive in situ hybridization for the detection and monitoring of trisomy 12 in B-cell chronic lymphocytic leukaemia.

Non-radioactive in situ hybridization (NISH) with a chromosome 12-specific alpha satellite probe was performed on 20 patients with chronic lymphocytic leukaemia (CLL) with normal karyotype (15 cases) or with inadequate mitotic yield (5 cases) from mitogen-stimulated cultures. All patients had over 70% lymphocytes coexpressing the CD5/CD23 antigens. While less than 1% interphase nuclei showed three fluorescent spots in 16/20 patients, evidence of trisomy 12 in 15-25% interphase cells was detected in four patients. According to the FAB classification the diagnosis in these patients was typical B-CLL, stage III (Rai's staging system) in one case, CLL/PLL, stage II and III in two cases, PLL, stage III in one case. In order to confirm these results, NISH was repeated after 1 month in one patient and after 2 years in three patients. All patients had been treated with chemotherapy in the period between the two NISH experiments. In all cases a 1.8-3-fold increase of percentage of trisomic interphase cells was detected. These findings suggest that in B-CLL clones with trisomy 12 may have proliferative advantage over clonal B-lymphocyte without +12 and, possibly, that they may be more resistant to chemotherapy. We conclude that NISH is a sensitive technique allowing for the detection and monitoring of trisomy 12 in a fraction of B-CLL patients with normal karyotype or with no analysable mitoses despite employment of polyclonal B-cell mitogens.

[Cytofluorometric study of myeloperoxidase (MPO) expression in neutrophilic granulocytes of subjects with primary or secondary MPO deficiency: analysis of the histographic antigen distribution using the Kolmogorov-Smirnov mathematical model]. / Studio citofluorimetrico della espressione della mieloperossidasi (MPO) nei granulociti neutrofili dei soggetti con deficit primitivo e secondario di MPO: analisi della distribuzione istografica degli antigeni secondo il modello matematico di Kolmogorov-Smirnov.

Neutrophil granulocytes from 12 subjects with primitive myeloperoxidase (MPO) deficiency (6 totally deficient) and 16 patients with secondary partial MPO deficiency were tested using two different anti-MPO monoclonal antibodies (MoAbs), in combination with a flow cytometer. Results demonstrated three different patterns of immunoreactivity with the MPO protein:i) a bright MPO antigenic expression, typical of patients with secondary MPO deficiency (comparable with that observed in the control group); ii) a medium MPO antigenic expression, typical of subjects with hereditary partial MPO deficiency; and iii) a dim MPO antigenic expression, characteristic of individuals with hereditary total MPO deficiency. No significant differences in granulocyte MPO reactivity were demonstrated for the two MoAbs. Furthermore, in two individuals with complete primitive deficiency, the single histogram analysis of MPO fluorescence seemed to show that only 38% (case 1) and 44% (case 2) of neutrophil were reactive with the MoAbs anti-MPO: the use of multiple histogram analysis in combination with Kolmogorov-Smirnov statistics allowed us to demonstrate that all the cells express a low density of MPO antigen. These data suggest that patients with primary MPO deficiency have different amount of MPO antigens in the neutrophils, and the levels of MPO fluorescence seem to decline concurrently with enzyme activity, thereby suggesting the presence of a diminished MPO production. On the contrary, in most cases of acquired MPO deficit, the reduced cytochemical activity contrasts with normal antigenic reactivity: this might be the result of the presence of an inactive enzyme.