Erythroid leukemia induced by Friend lymphatic leukemia virus in T-cell-depleted mice.

BALB/c mice depleted of T-cells by thymectomy at 3 to 5 days of age and by treatment with antithymocyte serum were inoculated with the lymphatic leukemia virus derived from Friend virus. After a long latent period, these animals developed erythroid leukemia. In contrast, intact control mice inoculated with Friend virus-associated lymphatic leukemia virus developed typical thymic (T-cell) lymphomas. Cell-free virus prepared from leukemic T-cell-depleted animals induced lymphoid, myeloid, and erythroid leukemias in intact mice. The erythroid leukemia-inducing virus differed from the spleen focus-forming component of Friend virus in its long latent period (88 to 225 days) and in its inability to induce spleen foci. End-point dilution experiments suggested that a hitherto undescribed component of the Friend virus complex might be responsible for these late-appearing erythroid leukemias.     

Changes of H-2 antigen expression on thymocytes during leukemia development by radiation leukemia virus

The expression of antigens encoded by the K and D region genes of the major histocompatibility complex on thymocytes of BL/6 mice infected with Radiation Leukemia Virus (RadLV) variants, A-RadLV to which they are sensitive or D-RadLV to which they are resistant, was investigated. Reduced thymus cellularity due to the thymolytic effect of both RadLV variants (30-40% cell reduction within 24 h after intrathymic virus injection) was accompanied with elevated H-2 expression on thymocytes. A high density of H-2D and to a lesser degree increased expression of H-2K were observed following infection with both virus variants. This elevated H-2 expression was maintained transiently for 6-7 weeks in the resistant situation and persisted in the sensitive situation until overt leukemia developed. The occurrence of A-RadLV transformed cells in 75% of the tested thymuses within 10 days after infection (vs 16% in D-RadLV treated mice) and their further expansion until overt leukemia developed could explain the continued expression of elevated H-2 expression on thymocytes in the sensitive situation. The majority (85%) of the primary A-RadLV induced leukemias tested expressed more H-2D/H-2K gene products than normal thymocytes. We conclude that leukemia development due to RadLV infection is not associated with the reduction or disappearance of H-2D/H-2K gene products.     

Avian erythroblastosis virus isolated from chick erythroblastosis induced by lymphatic leukemia virus subgroup A

A new strain of avian erythroblastosis virus (AEV), designated "AEV-H," was established by serial passages of a field isolate of avian lymphatic leukemia virus subgroup A [LLV(A)] in chicks from a White Leghorn flock of line 151 chicks. One stock of AEV-H contained 10(4) focus-forming units/ml virus and 10(9) tissue culture infective dose/ml LLV(A). All of the chicks that received ip inoculations of 0.2 ml AEV-H developed erythroblastosis complicated by fibrosarcoma 16-24 days (approximately equal to 17.7 days) after inoculation. Pathologic changes of erythroblastosis were macroscopically observed, mainly in such visceral organs as the liver, spleen, and bone marrow. In addition, microscopic changes were observed in the lung, kidney, ovary, and heart. Pathologic changes of fibrosarcoma were so conspicuous that they were recognizable by the naked eye in the pancreas and in the serous membrane of the intestine.     

Antibody to Epstein-Barr virus and cellular immunity in Hodgkin's disease and chronic lymphatic leukemia

Antibodies to Epstein-Barr virus capsid antigen (VCA), early antigen (EA) and cellular immunity as measured by skin reactivity to keyhole limpet hemocyanin (KLH) and Brucella antigen (BA) were measured in 15 cases of Hodgkin's disease (HD) and 14 cases of chronic lymphatic leukemia (CLL) before treatment and one year later. Both groups of diseases were associated with elevated VCA and EA antibody levels when compared with 18 controls, and in both groups the mean titers were unchanged after therapy. A negative skin test to KLH was associated with a short survival in the HD group and was found more frequently in CLL patients with active disease. In the young HD patients, a higher EBV titer was found in pretreatment sera of non-survivors compared with those who are still alive. There was no correlation, however, between tests for cell-mediated immunity and humoral antibodies against EBV. The finding of similar titers in patients with depressed and normal skin reactivity indicates that the elevated titers are probably not the result of a non-specifically depressed immune defense.     

Immunosuppression in mice after inoculation with 334C, a murine lymphatic leukemia-inducing virus.

334C murine leukemia virus, which induces a high incidence of lymphatic leukemias (80-90%) in susceptible mice following a long latency period, was found to cause a severe in vivo suppression of direct plaque-forming cells from the spleen, following antigenic stimulation with sheep red blood cells. Neonatally infected inbred BALB/c and outbred Ha/ICR Swiss mice, which develop a sustained viremia, were highly susceptible to the immunosuppressive effect of this virus as early as 1 week after virus infection, long before any detectable histologic evidence of leukemia development. Ha/ICR Swiss mice, which are highly resistant to the leukemogenic potential of this virus following infection in adult life, were highly resistant to its immunosuppressive action; only a moderate and transient suppression, without viremia, occurred 2 weeks after virus infection. In marked contrast, BALB/c mice were highly susceptible to the immunosuppressive action of 334C murine leukemia virus following infection in adult life; a severe and sustained suppression was observed as early as 1 week after virus infection and was followed by a sustained viremia, beginning at 2 weeks, with a 55-60% incidence of leukemia observed over a period of 1 year. Infectious virus was essential to produce theimmunosuppressive effect; heat-inactivated (56 degrees C/30 min) and attenuated (4 degrees C/4 1/2 mo) virus preparations were ineffective. The plaque-forming response of spleen cells from lethally irradiated syngeneic adult BALB/c mice was markedly suppressed following reconstitution with thymus-dependent (T) or thymus-independent (B) cells from the thymus and bone marrow, respectively, of virus-infected mice, in combination with each other, or with the appropriate cell populations from normal mice.     

Cellular immune response induced by the radiation leukemia virus (RadLV)

Studies on the cellular basis involved in the build up of immunity in C57BL/6 mice inoculated intrathymically with the radiation leukemia virus (RadLV) have been carried out. The virus inoculated C57BL/6 mice were resistant to isotransplantation of leukemic cells for two months after immunization. Lymphoid cells from immune mice present in the thymus, lymph nodes, spleen and peritoneal exudate were found to cause tumor growth retardation. RadLV inoculated C57BL/6 mice performed transplantation resistance only to leukemic cells induced by RadLV (127 LC), but not to radiation induced leukemias (XRL-1, XRL-2, XRL-3), to EL₄ or to any other syngeneic tumors tested. The immunological specificity of the lymphoid cells taken from immunized mice (with RadLV) was tested in vivo and in vitro against leukemic cells induced in C57BL/6 mice by various agents (RadLV, chemical carcinogens and X-rays) and were found to be highly specific for the presence of RadLV associated antigen(s) on their cell surface. A cytostatic effect rather than a cytolytic effect was demonstrated, when effector:leukemic cell interaction was tested in vitro. The cytostasis assay was performed on syngeneic leukemic cells (induced by RadLV) in suspension at various leukemic: effector cell ratios. A specific reaction occurred mainly at the ratio of 1:80.     

The combined action of Rauscher leukemia virus and lactic dehydrogenase virus on mouse lymphatic tissue

Mice inoculated with animal-passaged Rauscher leukemia virus contaminated with lactic dehydrogenase virus showed early gross and histological changes in their lymphatic tissues comparable to those in mice inoculated with lactic dehydrogenase virus alone. Some of the changes closely resembled those that have been ascribed to stress, which are mediated by corticosteroid hormones Except for early erythroblast activation, mice inoculated with a pool of animal-passaged Rauscher leukemia virus derived from cell culture and not contaminated with lactic dehydrogenase virus did not undergo these changes. Most notable were the absence of early lymphocyte destruction in thymus-dependent areas responsible for cell-mediated immunity and the lack of significant immunoblast activation and proliferation in lymphoid germinal centers (humoral immune compartment). The presence of lactic dehydrogenase virus in Rauscher leukemia virus pools or its addition to the uncontaminated pool resulted in an enhancement of the “erythro-blastic reaction” associated with Rauscher disease, as indicated by an increase in spleen weight. There was also prominent diffuse and persisting hyperplasia of germinal center cells (immunoblasts and immunocytes) after lactic dehydrogenase virus was added to the uncontaminated Rauscher virus pool. Furthermore, the presence of the lactic dehydrogenase virus enhanced the immunosuppressive properties of Rauscher leukemia virus. Two possibilities were considered to account for the enhancement of Rauscher disease by lactic dehydrogenase virus. First, by stimulating germinal center hyperplasia, the virus could supply greater numbers of target cells for Rauscher virus replication. Second, the depression of the cell-mediated immune response by lactic dehydrogenase virus could prevent the inactivation of Rauscher virus particles, or tumor cells by lymphocytes.     

Clonal development of lymphomas induced by Rauscher leukemia virus

The number of cells from which tumors induced by neonatal injection of Rauscher Leukemia virus (RLV) develop was investigated using F₁ (C57BL/6 X Feral) female mice heterozygous at the X-linked phosphoglycerate kinase (PGK) locus. Because of inactivation of one of the two X chromosomes in each somatic cell which occurs during embryogenesis in female mice, only one of the two PGK genes is active in each somatic cell. Thus, tumors that develop clonally in these mice exhibit one enzyme type, B or A, whereas those with a multicellular origin may exhibit both enzymes. Seventeen of 22 PGK heterozygous mice injected with RLV developed lymphosarcomas after an average latency of 38 weeks. Twelve of these lymphomas exhibit a single-enzyme type, A or B. In three of five tumors with double-enzyme phenotypes, the minor enzyme component comprised 20% or less of the total PGK activity, and histological examination revealed that these tumors contained a mixture of malignant and normal-appearing cells, suggesting that the minor PGK component was not contributed by the malignant cells. In the two remaining lymphomas, the ratio of A:B PGK activity was close to l:l. However, lymphomas which developed in recipients after transplantation of cells from these two tumors into newborn mice showed only single-enzyme PGK phenotypes, suggesting that the neoplastic cells in the primary tumors had single-enzyme phenotypes. Thus, these results indicate that lymphosarcomas induced by RLV in mice develop clonally.     

High- and low-leukemogenic variants of the radiation leukemia virus (RadLV): Immunogenic,suppressive and genetic properties in relation to leukemogenic activity

C57BL/6 (B6) mice inoculated with the highly leukemogenic variant of the radiation leukemia virus (A-RadLV) develop suppressor cells capable of abrogating potential anti-tumor immunity in vitro and in vivo, Inoculation of B6 animals with the low-leukemogenic D-RadLV variant does not result in suppressor cell generation but induces antitumor reactive lymphocytes. A-RadLV and D-RadLV are not leukemogenic in BALB/c or (B6 × BALB/c)F₁ (F₁) mice, and reactive but not suppressor lymphocytes could be demonstrated in F₁ animals inoculated with either virus. Infectivity assays and fingerprint analysis revealed that A-RadLV and D-RadLV contain viruses with N and B tropism. In addition, thymoma cells induced by A-RadLV produced another virus with a fingerprint pattern containing X-MuLV elements. The possible implications of the different virus types on the immunogenic and leukemogenic properties of the RadLV variants are discussed.     

Phenotypic characterization of mice of thymus target cells susceptible to productive infection by the radiation leukemia virus

The spread of virus replication was studied by electron microscopy in the thymuses of inbred C57BL/Ka mice after intrathymic inoculation of the radiation leukemia virus (RadLV). The first type C-budding virus particles appeared in scarce blast cells of the subcapsular zone. Most of these blast cells were "X-cells," i.e., the thymus lymphoid cells most actively engaged in DNA synthesis. Virus replication spread to the entire cortical blast cell population and, from day 7 on, to the small cortical lymphocytes. The first virus-producing cells were derived from a very few target cells (approximately 0.001-0.003% of thymocytes) susceptible to RadLV infection. For determination of the phenotypes of these target cells, various thymocyte subpopulations obtained through a battery of cell separation methods were tested for their ability to support the replication of RadLV/VL3 virus in short-term culture. Most of these target cells were sensitive to the lytic effect of hydrocortisone and migrated in the fastest fraction of a 1Xg sedimentation gradient, together with the majority of [3H] thymidine-incorporating blast cells. They exhibited an intermediate density and expressed H-2 and Thy 1,2 cell surface antigens, although they were not found preferentially among the high Thy 1,2 population to which most of the cortical blast cells belonged. The spread of RadLV within the thymus and the surface phenotype characteristics of target cells indicate that these cells correspond to the thymocyte subset at the earliest stage of thymic lymphopoiesis and may be transitional between the prothymocytes and the subcapsular blast cell population.     

Inhibition by tuftsin of Rauscher virus leukemia development in mice

The antitumor effect of tuftsin, the natural phagocytosis-stimulating peptide, on leukemia induced by Rauscher murine leukemia virus (R-MuLV) was studied in vivo in SWR inbred mice. Tuftsin was found capable of significantly increasing the survival of R-MuLV-infected mice. The peptide, when injected both ip and iv into mice, exerted its activity in a dose- and time-dependent manner. Optimal antitumor activity was achieved upon administration of 25 micrograms tuftsin 4 days before R-MuLV inoculation.     

Immunosuppression and reconstitution with thymosin after radiation therapy

Since 1976, 102 patients with advanced squamous cell carcinoma, (82, head and neck; 20, esophagus), have been evaluated before receiving irradiation and thymosin fraction 5 therapy at the University of California, San Francisco (UCSF). Thymosin fraction 5 is a mixture of at least 20 polypeptides which has been shown to have immune enhancing capabilities in primary immunodeficiency disease and various malignancies. Immunity prior to treatment (measured by total lymphocyte count, E and EAC rosettes, lymphocyte stimulation with phytohemagglutinin (PHA) and in mixed leukocyte culture (MLC) with allogeneic cells and quantitative serum immunoglobulins) was comparable and normal in the 80 control patients and the 22 thymosin treated patients. Postirradiation significant depression (p < 0.01) was demonstrated in cellular immunity in both groups of patients with decreased T and B cell numbers and depressed PHA and MLC stimulation. To date there have been an equal number of recurrences and deaths in both groups of patients.     

Abelson murine leukemia virus: Effect of helper virus from regressing friend virus on leukemia development

Replication defective Abelson murine leukemia virus (A-MuLV) induces a non-thymic lymphoma in vivo and transforms both hematopoietic and fibroblastic cells in vitro. In vivo leukemogenicity and the efficiency of in vitro transformation of hematopoietic cells by A-MuLV are known to be affected by the replication competent helper virus present in A-MuLV stocks. The helper virus isolated from the regressing strain of Friend virus (RF-MuLV) is responsible for the spontaneous regression of erythroleukemia induced by replication defective spleen-focus forming virus and itself induces a lymphocytic leukemia which spontaneously regresses. The diseases produced by A-MuLV stocks containing either RF-MuLV or Moloney leukemia virus, the helper virus associated with the original isolate of A-MuLV, were compared to determine if RF-MuLV can influence the disease produced by a replication defective virus with a discrete transforming gene. Both virus stocks induced leukemias with similar efficiency and gross pathology. Spontaneous regression was not observed when RF-MuLV was used as the helper virus. Examination of the leukemic cells and cell lines derived from leukemic tissues indicated that the target cell for A-MuLV transformation was not affected by the helper virus. Both transformed lymphoid and monocytic cells were cultured from leukemic tissues and established as cell lines. The lymphoid cells were phenotypically similar to pre-B cells or null cells, while the monocytic cell lines resemble promonocytes. The frequency with which promonocytic cell lines were isolated from leukemic mice suggests that A-MuLV leukemogenesis may often involve transformation of monocytic series cells as well as lymphoid cells. Thus, RF-MuLV can serve as an efficient helper virus for A-MuLV and does not appear to alter the in vivo target cell for transformation. It is unable, however, to alter the progressive course of Abelson virus induced disease.     

Characteristics of potential lymphoma-inducing cells in mice sensitive or resistant to lymphomagenesis by radiation leukemia virus variants

The relationship between the H-2-associated responsiveness of mice to radiation leukemia virus variants (A-RadLV and D-RadLV) lymphomagenesis and the characteristics of early occurring potential lymphoma-inducing cells (PLC) among thymus and bone marrow cells of these virus-infected mice was investigated. Sensitivity to virus-induced T-cell lymphomagenesis was shown to involve early occurrence of Thy-positive PLC, found predominantly among thymocytes, whereas resistance was rather related with early identification of PLC-Thy-negative cells mostly among bone marrow cells. PLC were further characterized in the sensitive (BL/6 + A-RadLV) and resistant (BL/6 + D-RadLV) situations by testing in parallel the tumorigenic potential (using the transplantation bioassay method) and type of thymus and bone marrow cell populations separated by different methods such as size fractionation by centrifugal elutriation, cytotoxic elimination of lymphocytes, or panning. The early occurring PLC among thymocytes of BL/6 mice 10-20 days following infection with A-RadLV were shown to be cortisone-resistant, Thy+, CD4+, and/or CD8+ medium size dividing thymocytes. PLC among thymocytes of BL/6 mice + D-RadLV, identified among the medium and large cell fractions, were shown to be cortisone-resistant Thy-, CD4-CD8- lymphocytes. High tumorigenic potential of PLC was demonstrated only among unseparated or separated (on size basis) bone marrow cells of BL/6 + D-RadLV (72-84%), whereas unseparated or separated fractions of bone marrow from BL/6 + A-RadLV had a low lymphomagenic potential (15-20%). The parallelism between the bone marrow fractions that induced optimal thymus cellularity following reconstitution of lethally irradiated mice and optimal lymphomagenicity stress the prothymocyte characteristics of PLC among bone marrow cells of BL/6 mice infected with D-RadLV. It is suggested that in resistant and sensitive haplotypes RadLV variants infect different cell populations and thereby induce PLC which differ in their capacity to present associative MuLV antigens with self H-2.     

急性淋巴细胞白血病骨髓细胞血管生成素2mRNA表达及其临床意义

Objective To study the expression levels and its clinical significance of angiopoietin 2 (Ang-2) gene in acute lymphatic leukemia(ALL). Methods The qualitative detection method was established with SYBR Green Ⅰ by real-time fluorescent quantitative PCR, and Ang-2 mRNA was measured in 51 cases of pre-therapeutic ALL. In addition, the expression of Ang-2 gene was also analyzed in 20 cases of non-malignant hematological diseases. Results The expression of Ang-2 gene was found in all the patients, and Ang-2 expression level in ALL patients was significantly higher than that of the controls (P<0.05). No significant relationship was found between Ang-2 expression level and clinical characteristics (age, haematogloblin, WBC count, platelet count, LDH, blast cells in peripheral blood, blast cells in bone marrow). The expression level of Ang-2 have no effect on one year replase rate and survival rate in ALL. Conclusion Ang-2 expression level in ALL patients was higher than that in non-malignant hematological diseases, and there may be no relationship with clinical manifestation, treatment and prognosis.     

急性淋巴细胞白血病骨髓细胞血管生成素2mRNA表达及其临床意义

Objective To study the expression levels and its clinical significance of angiopoietin 2 (Ang-2) gene in acute lymphatic leukemia(ALL). Methods The qualitative detection method was established with SYBR Green Ⅰ by real-time fluorescent quantitative PCR, and Ang-2 mRNA was measured in 51 cases of pre-therapeutic ALL. In addition, the expression of Ang-2 gene was also analyzed in 20 cases of non-malignant hematological diseases. Results The expression of Ang-2 gene was found in all the patients, and Ang-2 expression level in ALL patients was significantly higher than that of the controls (P<0.05). No significant relationship was found between Ang-2 expression level and clinical characteristics (age, haematogloblin, WBC count, platelet count, LDH, blast cells in peripheral blood, blast cells in bone marrow). The expression level of Ang-2 have no effect on one year replase rate and survival rate in ALL. Conclusion Ang-2 expression level in ALL patients was higher than that in non-malignant hematological diseases, and there may be no relationship with clinical manifestation, treatment and prognosis.