We recently reported that thymocytes from 6-month-old preleukemic AKR mice express higher levels of murine leukemia virus (MuLV)related antigens than thymocytes from 2-month-old mice. We have now found that the level of xenotropic MuLV (defined operationally as MuLV able'to infect mink cell cultures) is also-markedly increased in thymus of 6-month-old AKR mice and that-this increase in virus correlates closely with increased MuLV-antigen expression. There is no increase of MuLV antigen or xenotropic virus in spleen or lymph nodes. Production of ecotropic MuLV remains unchanged with age in thymus, lymph nodes, and spleen. Thymic grafts from 6-month-old AKR mice, but not from 2-month-old mice, induce both amplified MuLV-antigen expression and xenotropic virus production in the thymus of young AKR recipients. Experiments with lethally irradiated AKR mice reconstituted with syngeneic bone marrow cells indicate that age-related changes in the thymus rather than in bone marrow precursor cells are responsible for MuLV-antigen amplification.The critical role of the thymus in murine leukemogenesis is well known (1). In many strains of mice with a high incidence of spontaneous leukemia, the thymus is the first site of recognizable disease, and thymectomy early in life prevents its development (2). The great majority of such leukemias have T-cell markers (3), indicating that these cells have undergone some phase of their differentiation in the thymic environment. The etiology of mouse leukemia is complex, with murine leukemia virus (MuLV) (4, 5), genetic factors that limit or facilitate virus or leukemia cell replication and spread (5, 6), and humoral factors presumably elaborated by thymic stromal cells (1, 7) each playing a role.Before the onset of leukemia, characteristic changes occur in the thymus of mice from the high-leukemia AKR strain: (a) the thymic cortex is reduced in size, and structures resembling lymphoid follicles and germinal centers may appear in the medulla (1); (b) the level of adenylate cyclase in the thymus increases (8); and (c) the thymocyte undergoes a marked change in the expression of certain cell surface antigens (9, 10). We have reported recently that starting at about 4-5 months, MuLVrelated antigens (GIx, GCSA, p3O, and gp7O) and H-2 alloantigens on thymocytes show a progressive increase, whereas the differentiation alloantigen Thy-i is reduced (9).The present study is a further analysis of the preleukemic changes occurring in AKR mice, with the following questions Abbreviations: MuLV, murine leukemia virus; anti-NTD, (W/Fu X BN)F1 anti-W/Fu leukemia (C58NT)D antiserum. t Present address:

Thymocytes from preleukemic AKR mice aged 5-6 mo have an altered pattern of cell surface antigens. The expression of four MuLV-related antigens on the cell surface (GIX, GCSA, gp70, p30) is markedly increased in comparison to 2-mo-old AKR mice and approximates the heightened levels of these antigens found on thymic leukemia cells. H-2 and Thy-1 alloantigens also show characteristic modifications in relation to age and leukemia development. In contrast to the high Thy-1/low H-2 levels on 2-mo-old AKR thymocytes, thymocytes from 6-mo-old mice and thymic leukemia cells frequently show a low Thy-1/high H-2 surface phenotype. As thymocytes from mouse strains with a low incidence of leukemia do not show these changes, they appear to represent a stage in the conversion of normal cells to leukemia cells.

State of shock, deteriorated consciousness level, chronic obstructive lung disease, ischemic heart disease, hemorrhage requiring blood transfusion, age over 80 years, cardiovascular surgery, surgeries at night, and surgeries of duration more than 2 h cause patients to be strongly susceptible to postoperative mortality or morbidity in emergency surgeries.

The actual utility of a new classification system of acute myeloid leukemia (AML) recently introduced by the World Health Organization (WHO) has not been thoroughly investigated yet. In this study, we evaluated long-term outcomes of unselected AML patients categorized according to the new WHO classification. Between 1990 and 2002, 109 adult AML cases were referred to our hospital. For the entire population, the median survival duration was 1.2 yr with a 5-yr survival rate of 31%. AML with recurrent genetic abnormalities accounted for 26%, AML with multilineage dysplasia for 29%, therapy-related AML for 13%, and AML not otherwise categorized for 32% of classifiable cases. Among the four groups, a significant difference was observed in terms of overall survival (P < 0.0001). Univariate analysis showed that six variables affected survival: cytogenetic risk, age, multilineage dysplasia, prior chemo/radiotherapy, type of treatment (intensive or palliative), and transplantation. However, in multivariate analysis no adverse prognostic impact of multilineage dysplasia and prior chemo/radiotherapy was detected (P = 0.4979 and 0.8702), whereas cytogenetic risk and patient age maintained their prognostic value (P = 0.0005 and 0.0100). These results indicate that outcomes for AML patients appear to be distinguished on the basis of the WHO classification, but the prognostic significance of multilineage dysplasia and prior therapy is lost after adjusting for cytogenetic risk and age. Our findings suggest that the WHO classification may be strengthened by greater emphasis on genetic/cytogenetic information.

A randomized clinical trial of combination chemotherapy for adult acute lymphoblastic leukemia (ALL) with doxorubicin, vincristine and prednisolone with and without L-asparaginase (AdVP vs L-AdVP) was conducted, involving 58 institutions throughout Japan. After reaching complete remission (CR), patients were treated with the same regimen for more than 2 years. Among 166 evaluable cases of the 198 cases enrolled, CR rates were 63.1% (53/84) with AdVP and 64.6% (53/82) with L-AdVP (P = 0.837). Median survival times and 7-year survival rates were 12.7 months and 21.2% with AdVP, and 16.0 months and 22.3% with L-AdVP (P = 0.955 by generalized Wilcoxon test [GW], P = 0.952 by log-rank test [LR]). Median disease-free survival times and 7-year survival rates were 13.5 months and 23.8% with AdVP and 17.0 months and 30.6% with L-AdVP, showing some increments for L-AdVP but no statistical significance (P = 0.141 by GW, P = 0.300 by LR). Among the cases of extramurally confirmed FAB subtypes, CR rates were 75.9% (63/83) for the L1 subtype and 51.3% (39/76) for the L2 subtype (P = 0.001). As to adverse effects, pancreatitis was complicated more frequently in L-AdVP than in AdVP (P = 0.039). Other side effects such as hyperbilirubinemia, diabetes mellitus, diarrhea and hypofibrinogenemia were observed more frequently with L-AdVP, but with no statistical significance. Thus, addition of a single course of L-asparaginase in the induction phase of combination chemotherapy with doxorubicin, vincristine and prednisolone did not significantly enhance the effect of antileukemic treatment of adult ALL.

No abstract

We established one transgenic mouse line which developed pre-B leukemic lymphomas by introducing ret cDNA driven by the SV40 promoter and the mouse immunoglobulin (Ig) enhancer. Lymphomas developed not only in the lymph nodes and the spleen but also in the thymus between the ages of 7 and 21 weeks. Analyses of cell surface phenotypes and Ig gene rearrangement revealed that these tumors were surface IgM-B220+ pre-B lymphomas. The rearrangement pattern of the Ig heavy chain locus indicated that the tumor cells were mono- or oligoclonal. Northern blot analysis showed that the ret transgene was expressed at a high level not only in the tumors but also in the prelymphomatous lymphoid tissues. We found that the expression of N-myc was dramatically down-regulated in the tumor cells, while the expression of c-myc was rather stable. Further experiments demonstrated that ret gene product did not directly down-regulate the expression of N-myc in transformed pre-B cell lines by in vitro transfection assay. From these results, we conclude that under the control of Ig enhancer, the ret transgene affected B lymphocytes at the early maturation stage as a prerequisite for transformation, preferentially generating a unique maturation stage of pre-B lymphomas whose N-myc expression was developmentally down-regulated.

No abstract