Analysis of the p53 gene in myeloid malignancies associated with chromosomal abnormalities involving the short arm of chromosome 17.

p53 protein is encoded by a tumor-suppressor gene located on the short arm of chromosome 17. We looked for mutations or rearrangements of the p53 gene in five patients with acute transformation of a chronic myeloproliferative disorder and cytogenetic anomalies involving the short arm of chromosome 17. Two patients had a isochromosome i(17q); three more patients showed the presence of unbalanced translocations involving chromosome 17. One of these patients had a single base pair deletion, causing a frameshift mutation, in the exon 5 of the p53 gene. The karyotype of this patient showed a translocation t(5;17)(q11;p11), with loss of a normal homologue of both chromosomes 5 and 17. In all other cases the configuration of the p53 gene, as tested by PCR-SSCP analysis of exons 5 to 9 and Southern blot, was normal. Our data suggest that mutations of the p53 gene occur in a minority of hemopoietic malignancies characterized by monosomy for the short arm of chromosome 17. However, the unbalanced translocation t(5q;17p) could be a chromosomal abnormality specifically associated with loss of function of the p53 gene.

Cytogenetics and occupational exposure to solvents: a pilot study on leukemias and myelodysplastic disorders.

In a pilot study, 57 patients affected by leukemias or myelodysplastic syndromes were interviewed to identify potential exposure to organic solvents. Cytogenetic analyses were performed in 40 of the 57 patients. Unlike previous investigations, no association was found between the occurrence of chromosomal abnormalities and exposure to organic solvents. An original finding was a strong association between solvent exposure and myelodysplastic disorders (4 certainly exposed and 1 possibly exposed out of 11 patients). Such an observation warrants confirmation from case-control studies.

Trisomy 11 in myelodysplastic syndrome-derived acute myeloblastic leukaemias.

Here we report 3 cases of trisomy 11 observed in 1 patient with secondary acute myeloblastic leukaemia and in 2 patients with spontaneous acute myeloblastic leukaemia. In all 3 patients, the picture of overt acute leukaemia arose following a clinically established myelodysplastic syndrome. These findings, together with the previously reported occurrence of trisomy 11 in myelodysplastic syndrome and in acute myeloblastic leukaemia, suggest that this abnormality can be considered specifically associated with myelodysplastic syndrome and with the subsequent and related acute myeloblastic leukaemia.

Philadelphia-positive thrombocythemia with a complex translocation involving chromosomes 9, 15, and 22.

We report a case of Philadelphia chromosome (Ph) positive thrombocythemia with a complex translocation. G-banding analysis showed the predominant karyotype to be 46,XX,t(9;15;22). Southern blot analysis revealed a rearrangement within the breakpoint cluster region on chromosome 22 similar to findings in chronic myeloid leukemia. These data suggest the presence of a complex Ph translocation involving t(9;15;22)(q34.1 or q34.3;q26.1;q11 or q13).

Selective growth response to IL-3 of a human leukaemic cell line with megakaryoblastic features.

A new human leukaemic cell line (M-O7) with the phenotypic characteristics of CFU-mega is described. Its cells are positive for T200 leucocyte common antigen (LCA) and negative with MAbs recognizing T and B cells and mature myelomonocytic antigens. In contrast, they react with MAbs recognizing antigenic determinants common to multi-lineage (CD13, CD33, CD34) and to bipotent erythromegakaryoblastic (CD36, H25) haemopoietic precursors, and with MAbs specific for platelet glycoproteins (CD41w, CD42w). A small proportion (10%) of the cells were large and multinucleated, and on electron-microscopy examination showed peripheral splitting of platelet-like cytoplasm particles. When transferred to a serum-free Iscove modified Dulbecco's medium supplemented with human insulin and transferrin, M-O7 cells stop proliferating. Of the haemopoietic growth factors tested for their ability to restore the proliferative activity of this quiescent population, only rH IL-3 proved effective. Moreover, it also increased the cloning efficiency in methylcellulose more than any other CSFs. The M-O7 cell line may provide a valuable tool for the biological assay of IL-3, and a model for biochemical studies of the megakaryocytic lineage.

Duplication of Ph and of 9q+ chromosomes during the blastic transformation of a CML case.

We describe the blastic transformation of a case of chronic myelocytic leukemia in which, among other abnormalities, one extra Philadelphia and one extra 9q+ were observed. Molecular studies and analysis of the clonal evolution of the karyotype led to the interpretation of such an unusual finding as the result of nondisjunction, rather than of a double t(9;22) translocation.

A novel leukemia T-cell line (PF-382) with phenotypic and functional features of suppressor lymphocytes.

A human leukemia T-cell line (PF-382) spontaneously derived from the pleural effusion of a child with T-cell acute lymphoblastic leukemia is described. The cell line, which has been maintained in culture for over 10 months, has a modal number of 46 chromosomes and is characterized by a chromosomal abnormality, present in most of the cells, consisting of a translocation between chromosome X and chromosome 15 (46X,Xq-,15p+). The cells are not recognized by the OKT3 and OKT11 monoclonal antibodies (MoAb), nor do they form rosettes with sheep erythrocytes. By contrast, they react with the OKT6, Leu-1, and Leu-9 MoAb, which detect early T-lymphocytes, and express the more mature OKT8 antigen. The presence of the OKT8 marker is associated with suppressor activity on the pokeweed mitogen-induced proliferation and differentiation of normal B-cells, both by the PF-382 cells and by their supernatant. However, no cytotoxic activity against natural killer (NK)-sensitive target cells (K562) was found, indicating that the proliferating cells do not correspond to the subset of NK cells expressing the OKT8 antigen. Furthermore, the cells are incapable of both spontaneous and mitogen-induced interleukin-2 and interferon production. The ability of the PF-382 cell line to release a soluble factor(s) capable of modulating the differentiation of the B-cell compartment suggests that this new cell line represents a valuable model for the investigation of the interrelationships between T-cell subsets and other hematopoietic cell lineages.

[Effects of insulin on fibrinolytic and phagocytic activity of peritoneal macrophages in mice]. / Effetti dell'insulina sull'attività fibrinolitica e fagocitaria di macrofagi peritoneali di topo.

The effects of insulin on the in vitro fibrinolytic activity and on the ability to ingest inert latex particles of murine peritoneal macrophages were studied. The addition to the cell cultures of insulin at the concentration of 25 ng/ml significantly increased both fibrinolytic and phagocytic activities. These findings suggest that insulin may play an important role not only in the regulation of the cellular metabolic process but that also directly modulates specific cell functions.

[Expression of HLA-DR structure and a membrane-specific antigen by a granulocytopoietic line of acute leukemic blast cells]. / Espressione della struttura HLA-DR e di un antigene di membrana specifico per la linea granulocitopoietica sui blasti di leucemia acuta.

Blast cells from peripheral blood of 32 patients with acute leukemia were tested for their ability to react with a monoclonal antibody (D1.B6) specific for HLA-DR surface antigen. In order to evaluate the degree of leukemic cell differentiation a monoclonal antibody (R1.B19) specific for the granulocytopoietic lineage was also employed. The results demonstrated that a considerable proportion of blast cell populations expressed the HLA-DR antigen, while only a small fraction of cells expressed the myeloid antigen.

DNA synthesis and cell generation pattern of chronic lymphatic leukaemia lymphocytes stimulated by phytohaemagglutinin.

A detailed analysis of the cell recruitment and of the cell generation pattern of normal lymphocytes and chronic lymphatic leukaemia (CLL) lymphocytes, simulated by phytohaemagglutinin (PHA), was performed by the bromodeoxyuridiine (BUdR) Hoechst technique. It was found that in normal cultures the majority of cells divide two or three times, producing an early peak of DNA synthesis, while only a few cells grow exponentially and pass through many rounds of replication. On the contrary, the majority of CLL responsive cells grow exponentially, producing a delayed peak of DNA synthesis, while cells which divide only two or three times are scarce or absent. No difference in the minimal cell cycle length of the normal and the CLL exponentially growing population was found. In addition, a cell population recruited into cycle for the first time 5-6 days following PHA stimulation was observed in normal cultures but not in CLL cultures.

[Insulin receptors in the HL60 human promyelocytic leukemic cells line]. / Recettori insulinici nelle cellule della linea promielocitaria umana HL60.

The insulin binding characteristics of human promyelocitic HL60 cell line was studied by the use pf I(125) insulin. The binding activity was found to increase linearily both with the number of cells and with the incubation time. The competition curve with increasing concentration of unlabeled insulin demonstrated of specific receptors. The number of receptors was estimated to be 6.36 . 10(6) per cell.