James P. Okunewick

Possibility of graft-vs-leukemia determinants independent of the major histocompatibility complex in allogeneic marrow transplantation.

The role of major histocompatibility (MHC) versus non-MHC determinants in the antileukemic effect exerted by engrafted normal marrow (graft-vs-leukemia, GvL) was studied in Rauscher leukemic SJL/J mice. The marrow donor strains included normal syngeneic SJL/ J (H-2a), allogeneic C57BL/10 and 129/J (H-2b), congenic B10.S (H-2a, but otherwise genetically identical to the C57BL/10), and also F1 hybrid mice of the SJL/J and B10.S or C57BL/10 strains. Prior to transplant the recipients were exposed to a dose of total body irradiation that was large, but lower than that required to eliminate all hematopoietic precursors, such that GvL activity of the donor marrow would be necessary to avoid leukemic relapse. Total relapse within 60 days was observed when the syngeneic SJL/J donors were used. Transplantation either of the H-2b C57BL/10 or the H-2a B10.3 marrow resulted in approximately 50% unrelapsed survival at 4 months. In contrast, only 26% unrelapsed survival was obtained with H-2b 129/J marrow. Marrow from (SJL/J x B10.S)F1 hybrids yielded a survival curve that was intermediate between those for the two parental strains; a similar but somewhat improved, pattern was seen with (SJL/J x C57BL/10)F1-hybrid donors. The results suggest that although MHC genetic differences between the donor and recipient may produce a GvL effect in marrow transplantation therapy, other non-MHC determinants may also be capable of exerting an independent GvL effect of at least equivalent strength.

Radioprotective Effect of Rauscher Leukemia Virus in the SJL/J Mouse

Experiments have been performed to study the radiosensitivity of mice with Rauscher virus induced leukemia. Development of the leukemia was evaluated by measurements of the changes in spleen weight, leukocyte count and differentials, and hematocrit. Thirty-day survival of Rauscher virus injected mice was compared with that of normal mice following: no irradiation, 490, 650, 700, 750, 800, 850, 900, 950, 1000, 1050 and 1100 R of x-rays. Thirty-day survival of Rauscher infected mice given no irradiation was only 36%. This was increased to 100% by exposure to 490 R of x-rays. From 490 to 750 R the effect of irradiation on both normal and Rauscher infected mice was equivalent. However, from 800 through 1050 R the leukemic mice showed a notably greater radioresistance than did irradiated normal mice. Thirty-day survival of leukemic mice after exposure to 800 R was twice as great as that of normal mice (80% vs. 40%). At 900 R and above none of the normal mice survived for 30 days after the irradiation. In contr...

Assessment of the Radioprotective Capacity of Spleen Cells Transplanted from Mice with Rauscher Viral Leukemia

Rauscher leukemia virus infection induces a radioresistance in SJL/J mouse which is accompanied by increases in spleen cells and spleen CFUs of up to 17 times the normal. The present experiments have been carried out to directly evaluate the radioprotective ability of these spleen cells in relation to normal spleen cells. For this purpose spleen cells from both normal and leukemic mice were transplanted into lethally irradiated normal recipients. The results show that for the first 24 days after irradiation and cell transplant the radioprotective ability of the RLV-infected cells is at least equivalent to the normal. However after this time the survival curve of the recipients of RLV infected cells is adversely modified by the leukemia. Nevertheless, the number of survivors at 30 days is significantly large enough to conclude that the spleen cells of mice with Rauscher leukemia do protect against radiation caused mortality.

Interrelationship of erythropoietic recovery, marrow recovery, colony-forming units, and erythropoiesis-stimulating factors after sublethal x-irradiation.

Studies have been performed to compare the injury and recovery of various elements of the erythropoietic system after sublethal (200 R) exposure to x-rays. In the peripheral blood a distinct fall and an early (6-7 day) abortive rise in reticulocytes and newly formed hemoglobin could be seen, followed by a second drop and final recovery to normal levels at 2-3 weeks after exposure. A similar drop in total nucleated cells could be seen in both femoral marrow and spleen. However, splenic recovery was slow, whereas recovery to normal nucleated cell levels occurred by 5 days in the marrow. Transplantable marrow colony-forming units also showed delayed recovery reaching normal proportions at 16 days with no abortive rise. Total blood and plasma volumes showed only minimal changes, although there was a significant drop in hematocrit. Levels of erythropoiesis-stimulating factors (ESF) showed a slight increase consistent with the fall in hematocrit but no large fluctuations which could be easily correlated with th...

Comparative hematopoietic toxicity of doxorubicin and 4'-epirubicin.

Abstract 4′-Epirubicin is an anthracycline analog of doxorubicin which has been shown to be similar to doxorubicin in its anti-tumor activity but significantly lower in its cardiotoxicity. Therefore, it has been proposed as a potential clinical substitute for doxorubicin. Using the hematopoietic colony-forming unit, spleen (CFU-S) assay technique, direct comparison was made of the hematopoietic toxicity of the two drugs in vivo in a mouse model, and 4′-epirubicin was found to be significantly (P < 0.01) less toxic than doxorubicin. On a milligram per kilogram basis, the dose of 4′-epirubicin required to achieve a given level of hematopoietic progenitor cell kill was approximately 50% larger than that required for doxorubicin. Early CFU-S recovery following 4′-epirubicin exposure was also stronger than that achieved following doxorubicin, as was short-term peripheral white blood cell recovery. These findings confirm previous clinical suggestions that the acute toxicity of 4′-epirubicin toward hematopoietic progenitor cells might be less than that of doxorubicin. At the same time, however, when given in doses near their lethal limit, both drugs were shown to induce a chronic hematopoietic suppression. This was evident in the depressed long-term CFU-S levels following high doses of either drug, as well as in chronically depressed white blood cell levels following high-dose 4′-epirubicin.

Antiserum inactivation of hematopoietic colony forming stem cells from mice with Rauscher leukemia.

Nachweis, dass pluripotente Stammzellen von Mäusen mit Rauscher-Leukämie teilweise durch Rauscher-Virus-Antiserum inaktiviert werden. Ein Teil der pluripotenten Stammzellen scheint vom Virus befallen zu sein.

Methyl methane sulfonate induced enhancement of Friend viral leukemogenesis.

Exposure to the chemical carcinogen, methyl methane sulfonate, enhanced leukemogenesis in mice given threshold doses of Friend leukemia virus, as shown by peripheral white blood cell counts, splenomegaly and survival.

Stimulation of immune response in hybrid mice following Rauscher virus infection.

Summary The effect of Rauscher leukemia virus injection on the splenic PFC response to SRBC was measured in a mouse strain sensitive to the virus (SJL/J), one resistant to the virus (C57B1/10), and their F1 hybrid (SJL/JxC57B1/10)F1. In contrast to previous findings of a suppressive effect of Friend virus on PFC response in another hybrid of different resistant and sensitive strains, a significant immunostimulation was seen. Immunostimulation was also seen in the resistant parent when the PFC response level was measured 12 days or later after RLV infection, while the PFC response of the sensitive parent was nearly completely suppressed. Evaluation of the effect of RLV on the splenic masses of the three strains indicated a mild transient splenomegaly in the hybrid; a pronounced splenomegaly in the sensitive parent; and no effect on the resistant strain. Comparison of the data suggests that the change in splenic PFC number in the hybrid following RLV infection occurs as a function partially independent of changes in the total splenic mass.

Contrasting immune response following Rauscher leukemia virus infection in virus-susceptible vs. virus-resistant mice

Abstract Humoral (plaque-forming) and cellular (mitogenic) responses were monitored as a function of time after infection with a threshold lethal dose of Rauscher virus in virus-susceptible SJL/J mice and virus-resistant C57B1/mice. Plaque forming response was suppressed in the SJL/J, whereas in the C57B1/10, it was slightly elevated during the 2nd and 3rd weeks after infection; this correlated with a mild viremia. Increasing the dose of virus 40X did not significantly alter the humoral response pattern of either strain and did not cause the C57B1/10 response to mimic that of the SJL/J. For both strains the cellular immune response pattern differed from the humoral. Depression of T-cell mitogen responses occurred in the SJL/J, but at a later time than humoral response suppression. Neither T- nor B-cell mitogen responses were affected in the C57B1/10. The effect on mitogen responsiveness appeared to be independent of that on plaque-formation in both strains.

Graft-versus-Host Disease and Graft-versus-Leukemia in Experimental Systems

The development of monoclonal antibodies (MABs) has provided us with valuable new tools for studying the mechanisms of immune response. In our laboratories, we have been employing them in particular in the study of the role of T-cells in graft-vs-host (GvH) disease and in graft-vs-leukemia (GvL).