T-cell lymphoma induction by radiation leukemia virus in athymic nude mice.

We report the development of extrathymic lymphoblastic lymphomas in RadLV-inoculated congenitally athymic nude mice. Thus, a leukemogenic virus which appears to require the presence of a thymus for its replication in normothymic mice can infect and transform target cells in the absence of this organ in the athymic host. The cells of one of these lymphomas have been established in vitro as a permanent cell line, BALB/Nu1. This cell line as well as a lymphoma induced in NIH/Swiss nude mice exhibit several T-cell markers, including terminal deoxynucleotidyl transferase activity, Thy-1.2, and Ly-2.2, but not Ly-1.2 nor TL. Ig determinants were not detected. The characteristics of the tumor cells support the view that cells with T-cell markers may normally exist in nude mice and undergo neoplastic transformation and clonal expansion after infection with a leukemogenic virus. The alternative possibility that virus-induced differentiation of prothymocytes may lead to the expression of Thy-1.2 and Ly-2.2 antigens is also considered. BALB/Nu1 cells release large numbers of type C viral particles. The virus, designated radiation leukemia virus (RadLV)/Nu1, has RTase activity and the protein profile characteristic of murine leukemia virus (MuLV). In radioimmunoassays, it cross-reacts completely with RadLV/VL3, a virus obtained from RadLV-induced C57BL/Ka thymic lymphoma cells in culture, and slightly with a xenotropic virus (BALB:virus-2) and with AKR MuLV. On inoculation into C57BL/Ka mice it has thymotropic and leukemogenic activity. In vitro it is B-tropic, poorly fibrotropic, and has limited xenotropic activity. Thus, RadLV/Nu1 appears to be biologically and serologically similar or identical to its parent virus, RadLV.

The E mu-myc transgenic mouse. A model for high-incidence spontaneous lymphoma and leukemia of early B cells.

Mice transgenic for a c-myc gene driven by the IgH enhancer (E mu-myc) were shown to almost invariably develop lymphomas, 90% succumbing in the first 5 mo of life. The tumors typically presented as rapidly progressive lymphadenopathy with thymic involvement and were highly malignant by transplantation assay. Morphologically, they were lymphoblastic lymphomas, usually accompanied by lymphoid leukemia and granulocytosis, and were distinct from the tumors that arose much later in 37% of nontransgenic mice of the same (C57BL/6 x SJL)F2 genetic background. Cell-surface markers on 31 E mu-myc tumors identified 52% as pre-B lymphomas, 29% as mixed pre-B and B lymphomas, and 19% as B lymphomas. The tumors appeared to arise at random from a population of pre-B cells expanded by constitutive expression of the myc transgene. A majority of the animals initiated malignancy at the rate of 17% per week. The rate at which the cycling, benign pre-B cells spontaneously convert to malignancy was estimated to about 10(-10) per cell per generation. A transient leukocytosis identified in young E mu-myc mice was developed into a rapid assay for inheritance of the transgene.

Immunomorphologic classification of spontaneous lymphoid cell neoplasms occurring in female BALB/c mice.

WIth the use of a recently proposed, combined immunomorphologic classification (Pattengale-Taylor, 1981) for murine lymphomas and related leukemias, 70 spontaneously occurring lymphoid cell neoplasms from female BALB/cStCrl mice were evaluated and classified and then compared to the earlier Dunn classification (Dunn, 1954). The predominant lesion (i.e., 60% total incidence) in female BALB/c mice [previously called "reticulum cell sarcomas (neoplasm)", type B, by Dunn] was a lymphoid cell neoplasm derived from follicular center cells (i.e., follicular center cell [FCC] lymphoma). The B-cell nature was further confirmed in the majority (76%) of these FCC lymphomas by means of immunoperoxidase techniques that demonstrated the presence of cytoplasmic immunoglobulin (Clg). Smaller percentages of B-lymphoblastic (10% total incidence) and B-immunoblastic (7% total incidence) lymphomas were also observed. In addition, FCC, B-lymphoblastic, and B-immunoblastic lymphomas occurred in female BALB/c mice over 20 months of age. In contrast, Clg-negative lymphoblastic lymphomas involving the anterior mediastinum (and presumably T-cell in origin) occurred with a bimodal incidence in both young (13% total incidence at a mean age less than 6 mo) and old (10% total incidence at a mean age greater than 21 mo) female mice.

Characterization and classification of rat leukemias and lymphomas by membrane markers.

An immunological characterization of leukemias and lymphomas was made in the rat by using a panel of membrane markers in combination with morphological analysis. In the present study, five antigen markers and three surface markers were used for the characterization of 20 rat leukemias and lymphomas, and it was indicated that they could be divided into at least six groups. Of the lymphomas studied, six thymic lymphomas (Group 1) had the Thy-1.1 antigen, T-cell antigen, and receptors for guinea pig red blood cells; five extrathymic lymphomas (Group 2) lacked T- and B-cell antigens, receptors for guinea pig red blood cells, and surface immunoglobulin, but three of them had complement receptors. An absorption test revealed that Group 2 lymphomas possess a very low amount of the Thy-1.1 antigen compared to Group 1 lymphomas. None of the leukemias studied had detectable T- and B-cell antigen. Four leukemias had undifferentiated blast cell morphology and bore the Thy-1.1 antigen; three leukemias (Group 3) reacted with anti-lymphocyte serum, but one leukemia (Group 4) did not. Two leukemias (Group 5) had only the complement receptor and morphologically showed granulocytic appearance. Three leukemias (Group 6) had none of the membrane markers used and morphologically resembled erythroblasts. Based on these results, an attempt was made to classify these leukemias and lymphomas into T-cell lineage, B-cell lineage, stem cell, myeloid, and erythroid groups, respectively. Furthermore, the stage of differentiation in the lymphocyte maturational pathway of the leukemias and lymphomas belonging to Groups 1 to 4 is discussed.

Heterologous antiserum to chemically induced rat non-T, non-B leukemia and its application to characterization of rat leukemias.

Antisera to the 1-butyl-1-nitrosourea-induced "non-T, non-B" rat leukemia line DBLA-6 were raised in rabbits. Following absorption with syngeneic hepatoma cells, the antisera were very similar in specificity to antisera raised to rat Thy-1 antigen. Anti-DBLA-6 serum was cytotoxic in the presence of complement against 70 to 90% of thymocytes and 40 to 50% of neonatal spleen cells. In contrast, no significant cytotoxicity was observed against cells from bone marrow, lymph node, spleen, and peritoneum. An absorption test revealed that an antigen recognized by anti-DBLA-6 serum was present in brain tissue but absent in liver and kidney tissues. Nineteen rat leukemias and lymphomas were divided into six groups based on antigenic and morphological characteristics and the presence of receptor for guinea pig red blood cells. These tumors were investigated for the presence of the antigen recognized by anti-DBLA-6 serum. Of the leukemias and lymphomas studied, anti-DBLA-6 serum reacted with all thymic (Group 1) and extrathymic (Group 2) lymphomas and unclassified leukemias (Groups 3 and 4), while all myelogenous leukemias (Group 5) and erythroleukemias (Group 6) were negative. The position of leukemias and lymphomas reactive with anti-DBLA-6 serum in the lymphocyte maturational pathway is discussed.

Leukemia induced in rats but not mice by dimethyl morpholinophosphoramidate, a simulant anticholinesterase agent.

Dimethyl morpholinophosphoramidate (DMMPA), an organophosphate, caused leukemia in male and female Fischer 344/N rats. DMMPA was administered in corn oil by oral intubation to groups of 50 male and 50 female rats at 0, 150, 300, or 600 mg/kg body weight, five times per week for 2 years. B6C3F1 mice were given 0, 150 (males only), 300, and 600 (females only) mg/kg body weight under the same schedule. DMMPA induced a dose-related enhancement in the incidence of mononuclear cell leukemia in rats--males: controls = 14/50, 150 mg group = 21/50; 300 mg group = 19/50; 600 mg group = 25/50; females: controls = 9/50, 150 mg group = 13/50; 300 mg group = 12/49; 600 mg group = 18/50. Survival-adjusted rates strengthen the DMMPA effect: males--31%, 50%, 47%, and 63%; females--20%, 32%, 30%, 50%. Latent periods for mononuclear cell leukemia development in exposed rats were not shortened compared to controls. No carcinogenic effects in mice were detected. DMMPA was not mutagenic in Salmonella, was mutagenic for mouse lymphoma cells, and induced both chromosome aberrations and sister chromatid exchanges in Chinese hamster ovary cells.

How many types of erythroleukaemia are induced by retroviruses in mice?

Erythroleukaemia, until now defined by morphological criteria, has been observed in mice infected with several distinct virological entities, including the polycythaemia-inducing strains of Friend virus complex (FV-P), the anaemia-inducing strains of Friend and Rauscher virus complex (FV-A and RV-A, respectively) and various helper-independent virus isolates derived from the FV-A or RV-A complexes. Whereas erythroleukaemia develops rapidly (within 2-3 weeks) in mice infected with any strain of FV or RV, the helper-independent virus alone is pathogenic in mice only if they are infected neonatally. We now describe how two biological markers can be used to distinguish among the otherwise confusing array of virus-induced erythroleukaemias in mice. The evidence suggests that there are three different classes of this disease: (1) those (S+E+) from which both defective spleen focus-forming virus (SFFV) and erythropoietin-independent, erythroid colony-forming units (CFU-EI) can be recovered, (2) those (S+E-) from which only SFFV (but not CFU-EI) can be recovered, and (3) those (S-E-) from which neither SFFV nor CFU-EI can be recovered. There is a consistent association between the type of virus used to induce the erythroleukaemia and the class of the disease induced.

Clonal heterogeneity of anti-AKR/gross leukemia virus cytotoxic T lymphocytes. Evidence for two distinct antigen systems.

AKR/Gross leukemia virus-induced tumor reactive cytotoxic T lymphocyte (CTL) clones were derived from C57BL/6 spleen cells. Analysis of their specificity pattern was performed by using a panel of target cells such as E male G2 and AKR.H-2bSL1 (susceptible tumors to polyclonal anti-AKR/Gross virus CTL), and cl. 18-5 and cl. 18-12 (insusceptible variant sublines derived from AKR.H-2bSL1). Several of these CTL clones were selected for further study. Lysis of Gross cell surface antigen-positive tumor cells by these clones was restricted by the H-2Kb molecule. The cell surface phenotype of these clones was Thy-1.2+, Lyt-2.2+, L3T4-, a phenotype consistent with that of polyclonal anti-AKR/Gross CTL, suggesting that they were of conventional CTL origin. According to their fine specificity pattern, the CTL clones were divided into two major groups (A and B) which were further subdivided into five and three subgroups, respectively. The specificity of group A clones was essentially the same as that of the standard polyclonal CTL population except for a variable level of natural killer-like activity by some of the CTL clones. That is, group A clones did not efficiently lyse the insusceptible variant tumors nor any of Friend-Moloney-Rauscher-positive tumors tested, but they showed strong lytic activity to susceptible tumors and iododeoxyuridine-treated insusceptible variants. Thus, their CTL activity appeared to be strictly directed to Gross cell surface antigen-positive tumors that are susceptible to polyclonal anti-AKR/Gross virus CTL. In contrast, group B clones could lyse both susceptible and insusceptible variant tumors and also a Friend virus-induced tumor (FBL3). Therefore, as defined by these CTL clones, at least two distinct antigenic systems (A and B), each with several antigenic determinants, appeared to be present. Because recent findings suggested that most of the polyclonal anti-AKR/Gross virus CTL activity appeared to be directed to N-ecotropic proviral determinants, we further investigated the nature of these two antigenic systems by use of additional target cells including lipopolysaccharide (LPS)-stimulated spleen cell blasts from AKXL recombinant inbred strains and retrovirus-infected fibroblasts. Group A clones could lyse all LPS blasts derived from AKXL recombinant inbred strains containing the AKV-1 proviral genome, but lysed only very insufficiently or did not lyse AKV-1-negative blasts containing the AKV-3 and/or AKV-4 provirus.(ABSTRACT TRUNCATED AT 400 WORDS)

Glycolipid changes in murine myelogenous leukemias: neutral glycolipids as markers for specific populations of leukemias.

We have studied the glycolipid composition of six different murine myelogenous leukemias as well as that of T-cell leukemias and normal spleen cells. Neutral and acidic lipid fractions were isolated by column chromatography on DEAE-Sephadex and analyzed by high-performance thin-layer chromatography (HPTLC) and an HPTLC overlay method. Murine myelogenous leukemias were found to contain globo- and ganglio-series neutral glycolipids, e.g., glucosylceramide (Glc-cer), lactosylceramide (Lac-cer), globotriaosylceramide (Gb3), globoside (Gb4), Forssman glycolipid (Gb5), and asialo-GM1 (GA1). Monoblastic leukemia cells contained increased proportions of Gb3, Gb4, Gb5, and GA1. Monocytic and myelomonocytic leukemia cells contained increased proportions of Glc-cer and Lac-cer. Especially, Glc-cer accounted for approximately 60% of the total neutral glycolipids in monocytic leukemia cells. Gb3 was the major neutral glycolipid in reticulum cell neoplasm type A, and it accounted for approximately 75% of the neutral glycolipids. GA1 was the major neutral glycolipid in myeloblastic and granulocytic leukemia cells as well as T-cell leukemias. Especially, granulocytic leukemia cells contained predominantly GA1, and it accounted for approximately 80% of the total neutral glycolipids. The pattern of gangliosides in myelogenous leukemias was more complex when compared with that of the neutral glycolipids; murine myelogenous leukemias contained at least 13 gangliosides, including such major gangliosides as GM1, GM1b containing N-acetyl neuraminic acid and N-glycolyl neuraminic acid, and Ga1NAc-GM1b. Alterations of glycolipid composition in murine myeloid leukemias may be associated with cellular differentiation and maturation, and therefore these characteristic glycolipid species may be regarded as markers for specific populations of leukemia cells.