Generation and characterization of IL-2-activated bone marrow cells as a potent graft vs tumor effector in transplantation

The potential of bone marrow transplantation as an immunotherapeutic modality, using biomodulation of the marrow cells has been ignored in autologous transplantation. Furthermore, many common cancers such as lung, colon, prostate, and pancreas are resistant to even transplant doses of conventional agents and hence require novel approaches such as biomodulation. This study shows that we can generate cytotoxic killer cells similar to lymphokine-activated killer cells capable of lysing NK-resistant tumor cells in vitro if we incubate human or murine bone marrow in IL-2. This was accomplished without affecting the ability of the bone marrow to fully reconstitute mice similar to that of fresh nonactivated bone marrow. Studies evaluating the IL-2 activated human bone marrow in vitro also indicated that these activated bone marrow have similar CFU to that of fresh human marrow. Furthermore, in murine in vivo studies, the activated bone marrow (ABM) caused significant tumor regression in tumor-bearing mice. Also, these ABM cells had similar or higher tumoricidal activity and longer kinetics than spleen lymphokine-activated killer cells in vitro. Also, the ABM had purging ability in vitro. Therefore this IL-2 ABM could be used as an active therapeutic tool and not just as a passive rescue element in the autologous bone marrow transplantation setting.     

NK cells in allogeneic bone marrow transplantation

NK cells, until recently an ignored subset of lymphocytes, have begun to emerge as important cytotoxic effectors. It is now accepted that NK cells together with T cells constitute major actors in graft-versus-leukemia reaction after allogeneic bone marrow transplantation (BMT). Over the last several years the mechanisms regulating the activation of NK cells have been the subject of intense investigations encouraged by the clinical implications that these studies will have. This article provides a general overview of NK-cells biology and regulation pertinent to their function in allogeneic BMT, followed by a review of the in vivo preclinical and clinical evidence for the beneficial effect of NK cells in the adoptive immunotherapy of leukemia.     

Serum immunoglobulin levels following allogeneic bone marrow transplantation

In order to study the posttransplant evolution of serum immunoglobulin levels, we measured serum IgG, IgA and IgM levels in 50 recipients of allogeneic bone marrow before transplantation and at different intervals thereafter (days 39, 120, 365 and 730). IgG and IgM levels were depressed for 1 year and IgA levels for 2 years posttransplant. Immunoglobulin deficiency was more severe and prolonged in patients with graft versus-host-disease. Hypogammaglobulinemia may contribute to the frequent infections observed in these patients, especially those with chronic graft-versus-host disease.     

Linomide administration following bone marrow transplantation in mice

The effect of linomide, an immunomodulatory drug, on natural killer (NK) cells and T cell-dependent immune responses following syngeneic or allogeneic bone marrow transplantation (BMT) was investigated in BALB/c mice inoculated with B-cell leukemia (BCL1). Linomide given in the drinking water had no impact on graft survival or graft versus leukemia (GVL) effects. Although linomide regulates anti-self reactivity in mice with experimental and spontaneous autoimmune disorders, the anti-tumor effects induced by allogeneic donor lymphocytes were not affected. This indicates that different mechanisms regulate anti-self and anti-leukemia effects. Alternatively, linomide might affect the homing of self-reactive lymphocytes to specific target organs in autoimmune disorders, although the homing process may not be relevant to the control of leukemia by alloreactive lymphocytes.     

Induction of graft versus leukemia effects by cell-mediated lymphokine-activated immunotherapy after syngeneic bone marrow transplantation in murine B cell leukemia

 The feasibility of inducing graft versus leukemia (GVL) effects with allogeneic T cells in recipients of autologous bone marrow transplantation (BMT) was studied in a murine model (BCL 1) of human B cell leukemia/lymphoma. Allogeneic cell therapy, induced by infusion with peripheral blood lymphocytes, a mixture of allogeneic spleen and lymph node cells and allogeneic activated cell therapy, induced by in vitro recombinant-interleukin-2(rIL-2)-activated allogeneic bone marrow cells in tumor-bearing mice, prevented disease development in adoptive BALB/c recipients. Concomitant in vivo activation of allogeneic lymphocytes with rIL-2 suppressed even more effectively the development of leukemia in secondary adoptive recipients of spleen cells obtained from treated mice. In contrast, in vivo administration of rIL-2 after syngeneic BMT, with or without equal numbers of syngeneic lymphocytes, led to disease development in secondary recipients. Our data suggest that effective cell therapy can be achieved after SBMT by allogeneic but not syngeneic lymphocytes and that anti-leukemic effects induced by allogeneic lymphocytes can be further enhanced by in vitro or in vivo activation of allogeneic effector cells with rIL-2. Therefore, cell therapy by allogeneic lymphocytes following autologous BMT could become an effective method for inducing GVL-like effects on minimal residual disease provided that graft versus host disease can be prevented or adequately controlled. Received: 14 May 1996 / Accepted: 6 August 1996     

Dynamics of lineage-restricted mixed chimerism following sex-mismatched allogeneic bone marrow transplantation

Scant knowledge is available about the dynamics of lineage-specific mixed chimerism (Ch) following bone marrow transplantation (BMT). This review is focused on findings derived from bone marrow (BM) biopsies in patients with chronic myeloid leukemia (CML) including a sex-mismatched host/donor constellation. Appropriate techniques involved immunophenotyping by monoclonal antibodies to identify the various cell lineages, dual color fluorescence in situ hybridization (FISH) with x- and y-chromosome-specific DNA-probes and a proper detection system for a simultaneous labeling of the bcr/abl locus. A significant degree of Ch with more than 20% host CD34+ progenitors was found in the early and late (up to 200 days after BMT) posttransplant period. However, only 10% of these cells harbored the bcr/abl translocation gene. This result fits well with corresponding molecular biological findings of so-called minimal residual disease. Conversion of Ch evolved during leukemic relapse with 90% host progenitors of which 50% revealed the bcr/abl locus. A Ch of nucleated erythroid percursors (5%) and CD68+ macrophages (8%) was expressed to a significantly lower degree. The slightly increased frequency found in CD61+ megakaryocytes (16%) was probably due to the polyploid state of these cells. Similar to the CD34+ progenitor cells abrupt changes from donor to host type was associated with an insidious transformation into recurrent leukemia. The CD34+ endothelial cells showed a minor degree of Ch, because donor-derived elements ranged from 18% to 25%. Leukemic relapse was characterized by an almost complete conversion of the endothelial cells to a host type. These findings point towards a CD34+ progenitor cell origin of the (leukemic) endothelial cell layer and suggests that their dysfunction may contribute to an expansion of the neoplastic clone.     

Characterization of effector cells with anti-Candida activity obtained from murine bone marrow cells cultured in the presence of rhG-CSF: comparison between normal and CY-treated mice

Bone marrow cells (BMC) obtained from normal and cyclophosphamide (CY)-treated mice were cultured in the presence of recombinant human granulocyte-colony stimulating factor (rhG-CSF) and their effector cell activities inhibiting growth of C. albicans were examined. When BMC from CY-treated mice were preincubated with 0.05 ng/ml of rhG-CSF, effector cells with enhanced anti-C. albicans activity were recovered in the adherent cell population, whereas anti-C. albicans activity of BMC from normal mice was found in the non-adherent cell population. During culture without the presence of rhG-CSF, nonadherent BMC, seemingly granulocytes, from normal mice showed apoptotic change, but addition of rhGCSF clearly inhibited this change. On the other hand, when BMC from CY-treated mice were cultured with rhG-CSF, adherent cells as the main effector had the appearance of monocytes. These differences between the effectors with anti-C. albicans activity obtained from normal and CY-treated mice are discussed.     

Genetically determined resistance to foreign bone marrow transplantation in mice: characterization of the effector cells

Mice of most strains show a genetically determined ability to reject a variety of foreign marrow grafts even after lethal irradiation. The phenomenon is both host strain and donor marrow graft-dependent. To characterize the effector cell responsible for graft rejection, attempts were made to 1) determine to what morphologic subclass it belongs; 2) determine its life span; and 3) establish whether genetically different host environments influence the functioning of the effector cell. Mice of the 129/J strain (normally nonresistant), C57BL/6 strain (made non-resistant), and the homozygous mutants of C57BL/6, i.e., C57BL/6 (bg/bg), were recipients of C57BL/6 marrow or spleen cells. After lethal irradiation, hosts were given marrow or spleen cells from normal, strongly resistant C57BL/6 donors pretreated with a) 950 R whole body irradiation or b) twice daily injections for 4 days of the cell cycle toxic drug hydroxyurea followed by 950 R. In other cases, hosts were recipients of the lymphoid cell-rich fraction of marrow from irradiated C57BL/6 donors or adherent cells taken from cultures of marrow cells of unirradiated C57BL/6 donors. Three hours after receiving C57BL/6 marrow or spleen cells, irradiated hosts were given allogeneic DBA/2 marrow (always strongly rejected by C57BL/6 mice and always accepted by 129/J strain mice). Seven days later, host spleens were removed and the numbers of microscopic colonies were counted from subserial sections. The results demonstrate that 1) mice either normally or rendered nonresistant to a marrow allograft can be made to develop resistance by the administration of either whole spleen cells or marrow lymphoid cells from lethally irradiated strongly resistant donors; 2) adherent cells from cultures of marrow from strongly resistant mice are ineffective in conferring resistance; 3) the cell effective in conferring resistance has a life span greater than 4 but less than 7 days; and 4) the effector cell can function in genetically different environments of nonresistant strains.     

Suppression and elimination of BCL1 leukemia by allogeneic bone marrow transplantation

Mice carrying the B cell leukemia (BCL1)+ were successfully treated by total lymphoid irradiation (TLI), cyclophosphamide, and allogeneic bone marrow (BM) transplantation. Long-term survivors were examined for residual BCL1 cells and for the ability to transfer adoptively graft vs. leukemia (GVL) activity. Residual BCL1 cells could not be detected in the allogeneic BM chimeras (greater than 14 to 16 months) with the use of indirect immunofluorescent staining with anti-idiotype antibody. However, residual tumor cells were present in 50% of the "cured" chimeric mice since adoptive transfer of 10(6) spleen cells from 50% of the treated chimeric mice caused leukemia in BALB/c recipients. In order to determine whether leukemia had been prevented in the "cured" chimeras by a persistent cell-mediated mechanism, BALB/c mice were injected with 10(6) spleen cells from the "cured" BM chimeras together with a dose of 10(2) or 5 x 10(5) BCL1 cells. Onset of leukemia was delayed or completely abolished in a significant proportion of recipients receiving the cell mixtures, suggesting the presence of anti-tumor immunity in the cured mice. The data suggest that a persistent active immune mechanism may be responsible, in part, for the significant antileukemic effects observed in mice tolerant to donor alloantigens.     

Alkaline and acid phosphatase activity in murine femoral bone marrow following X-irradiation, or X-irradiation and repopulation with syngenic or allogeneic bone marrow or marrow stroma cells

The activity of alkaline and acid phosphatases in the bone marrow from the femoral cavity was investigated in the following groups of mice: (1) normal (non-irradiated); (2) irradiated with 600 R; (3) irradiated and repopulated with syngeneic bone marrow; (4) irradiated and repopulated with syngeneic marrow stroma; (5) non-irradiated, infused with allogeneic bone marrow (host versus graft reaction, HvG); (6) irradiated and repopulated with allogeneic bone marrow (graft versus host reaction, GvH). In addition, the activity of alkaline and acid phosphatases was examined in bone marrow stromal cultures. In irradiated animals the activity of both enzymes was lower than in non-irradiated ones, repopulation with syngeneic bone marrow restoring it to normal. Repopulation with allogeneic marrow (GvH) resulted in a very deep reduction of alkaline, but not acid, phosphatase. It is postulated that the decrease in bone marrow alkaline phosphatase activity can be a sensitive test for the early GvH reaction, preceding such parameters as splenomegaly. Marrow stroma cultured in vitro also showed very low alkaline phosphatase activity.     

Interleukin 2 regulation following semi-allogeneic bone marrow transplantation in mice

Success of allogeneic and autologous bone marrow transplantation (BMT) is hampered by susceptibility to infection during the first two post-treatment years. Further, in treating malignant diseases, impaired anti-host reactivity for donor cells may contribute to a high rate of relapse. Both complications are a consequence of immune deficiency involving B and T lymphocytes. The present study evaluates several key parameters of the immunologic reconstitution mechanism in mice subjected to myeloablative total body irradiation following semi-allogeneic (parental) BMT. This resulted in a gradual reduction of splenic CD3, CD4 and CD8 cells until day 45 post-BMT. Concomitantly, there was an increase in monocytes and CD4⁺/CD8⁺ (double positive) cells, accompanied by a persistent elevation in the percentage of B lymphocytes. The total thymic and splenic T cell populations were reduced until day +30. The cellular reduction correlated with the poor proliferative response of the thymic and splenic cells. A decrease occurred in IL-2 mRNA expression in thymic cells during days 15–20 post-transplant, corresponding with the low level of IL-2 secretion in the spleen and thymus of the transplanted mice. In conclusion, following semi-allogeneic BMT, there was an overall immune down-regulation in the cells, gene and protein levels. Reduced immunological responsiveness following BMT reinforces the need for improving the immune dysfunction by immunotherapy post-BMT.     

Graft-versus-host disease in experimental allogeneic bone marrow transplantation

Considerable progress has been made in defining the relative contributions of CD4+ and CD8+ cells to GVHD. Studies in mice have shown that, in isolation, each T cell subset is able to induce lethal GVHD in irradiated hosts. For hosts differing at the MHC (H-2), CD4+ cells cause GVHD directed to H-2 class II antigens whereas CD8+ cells produce GVHD to H-2 class I antigens. With H-2-matched hosts expressing multiple minor H antigens, induction of lethal GVHD is largely under the control of CD8+ cells. Which particular minor H antigens provide the targets for GVHD in mice is still unclear. Clarifying this question is complicated by the finding that the target antigens for GVHD do not necessarily correlate with the targets for cytotoxicity measured in vitro; moreover, immunodominance occurs when T cells are exposed to multiple minor H antigens in vivo. In terms of clinical application, there is a need to devise animal models for improving the success of HLA-matched bone marrow transplantation. Selectively depleting the marrow inoculum of CD8+ cells and preimmunizing the donor against viral pathogens are two procedures which are currently under study.     

Dynamics of bone marrow changes in patients with chronic idiopathic myelofibrosis following allogeneic stem cell transplantation

Scant knowledge exists about the dynamics of fibro-osteosclerotic bone marrow (BM) lesions and regeneration of hematopoiesis following allogeneic peripheral stem cell transplantation (SCT) in chronic idiopathic myelofibrosis. Therefore, an immunohistochemical and morphometric study was performed on BM biopsies in 20 patients before and at standardized intervals (days 30 through 384) following SCT. In responding patients, a total regression of the pretransplant increased fibrosis was completed in the posttransplant period after about six months, while the extent of osteosclerosis did not change significantly during observation time. The quantity of CD61+ megakaryocytes including precursors was strikingly variable after SCT and, by using planimetric methods, atypical microforms exhibiting a dysplastic aspect could be demonstrated. These anomalies may be responsible for posttransplant thrombocytopenia. CD34+ progenitor cells were increased before transplantation, however, their number declined rapidly to normal values in responding patients. Nucleated erythroid precursors revealed a decreased amount before and after SCT accounting for anemia. Large clusters of this cell lineage indicated an initial hematopoietic reconstitution comparable with the expansion of the neutrophil granulopoiesis. Proliferative activity and apoptosis showed an increase until one year after SCT that implied a still regenerating hematopoiesis in keeping with an enhanced cell turnover.     

Prometaphase accumulation in murine bone marrow cells following in vivo treatment with alloxan

The aim of this study was to determine the effect of alloxan, an inhibitor of N-acetylglucosaminyl transferase that acts during the G2/M transition, on the course of mitosis in murine bone marrow cells. Mitotic cells from animals treated with different doses of alloxan were analyzed for the frequency of prometaphasic and metaphasic chromosomes based on their morphology and length. The results indicate that alloxan treatment substantially increases the frequency of prometaphase chromosomes. This suggests that N-acetylglucosaminyl transferase is also involved in the G2/M transition in bone marrow cells. Alloxan treatment also provides a method for obtaining large chromosomes for the analysis of chromosome bands, FISH and sister-chromatid exchanges.     

Nonmyeloablative bone marrow transplantation of BXSB lupus mice using fully matched allogeneic donor cells from green fluorescent protein transgenic mice

Male BXSB mice, a mouse model of systemic lupus erythematosus, were given bone marrow transplants (BMT) at 20 wk of age using MHC-matched donor cells and nonmyeloablative conditioning (550 cGy irradiation). Transplanted mice and irradiation controls were followed for a period of 20 wk. Mice transgenic for green fluorescent protein were used as donors to allow tracking of donor cells and a determination of chimerism. Radiation controls had reduced renal pathology at 10 wk posttransplant, but not at 20 wk compared with untreated mice, while nonmyeloablative BMT mice had significantly reduced pathology at both time intervals. The monocytosis characteristic of older BXSB mice was also reduced by BMT, but the treatment did not prevent production of Ab to dsDNA. A stable chimerism of 24-40% donor CD45-positive cells was achieved in spleen and bone marrow, and there was no evidence of clinical graft vs host disease. Donor cells were detected in most recipient organs, notably the thymus and renal glomeruli. The results suggest that complete depletion of mature lymphocytes or of progenitor stem cells is not required to control lupus nephritis in BXSB mice.