[Experimental study of optimized H-2 haploidentical hematopoietic engraftment for the treatment of murine acute leukemia model]

OBJECTIVE

To explore the critical dose of T lymphocyte for preserving graft versus leukemia (GVL) while preventing GVHD in murine acute leukemia model treated with H-2 haploidentical hematopoietic stem cell transplantation (HSCT).

METHODS

(C57BL/6 x 615) F1 (H-2bk) mice which was inoculated with L615 cells to develop leukemic murine model was the recipient. The healthy C57BL/6 (H-2b) mice was the donor. CD(34)(+) cells from bone marrow and CD(3)(+)cells from spleen of the donor were purified by miniMACS. The purity of CD(34)(+) cells and CD(3)(+) cells were (81.5 +/- 2.4)% and (95.4 +/- 2.9)% respectively. Sixty-nine recipient mice were divided into seven groups. Group A received no treatment, group B received TBI only, the rest groups were irradiated 9 Gy by (60)Co and transfused 10(5) CD(34)(+) cells or mixed with 10(7) (E), 10(8) (F), 1.5 x 10(8) (G) of CD(3)(+) cells respectively. The mice were raised for 60 days, The cause of death was identified by pathology.

RESULTS

All mice in group E survived more than 60 days being significantly longer than that in the rest groups (p < 0.0001). The chimerisms from donor were 100% in the mice survived > 60 days. Mice died of leukemia relapse in group D and group E were significantly less than those in group C (p < 0.001). Mice died from GVHD in group G were significantly more than those in group E and group F (p < 0.001).

CONCLUSIONS

The leukemia relapse rate was highest in mice that were transplanted with CD(34)(+) cells alone. Those mice transfused with CD(3)(+) T lymphocyte in the graft higher than 10(8) cells died from the GVHD was significantly higher. The inclusive dosage of 5 x 10(7) CD(3)(+) T lymphocyte was enough to separate the GVHD from GVL.

Complete remission of tumour with interleukin 2 therapy in a patient with non-Hodgkin's lymphoma post allogeneic bone marrow transplant associated with polyclonal T-cell bone marrow lymphocytosis

A patient with low-grade non-Hodgkin's lymphoma (NHL) who relapsed shortly after an allogeneic bone marrow transplant (BMT) is reported. The patient was treated with interleukin 2 (IL-2), which resulted in a flare-up of graft-versus-host disease followed by disease control, with disappearance of peripheral lymphadenopathy. Sequential bone marrow testing showed the disappearance of bone marrow involvement with disease but occurrence of T-cell aggregates post IL-2 that were identified as polyclonal by molecular methods. The patient remains in complete remission 37 months following allogeneic BMT.

Peyer's patch is the essential site in initiating murine acute and lethal graft-versus-host reaction

Acute graft-versus-host disease (a-GVHD) is initiated primarily by immunologically competent cytotoxic T cells (CTLs) that express anti-host specificities. However, the host lymphoid compartment in which these precursor CTLs are initially stimulated remains unclear. Here we show that gut Peyer's patches (PPs) are required to activate anti-host CTL responses in a well characterized murine acute graft-versus-host reaction (a-GVHR) model, involving transfer of parent lymphocytes into F1 hybrid recipients. The a-GVHR was prevented when recruitment of donor T cells into PP was interrupted either by disrupting the gene encoding chemokine receptor CCR5 or by blocking integrin alpha(4)beta(7)-MAdCAM-1 (mucosal vascular addressin) interactions. Mice deficient for PPs failed to develop a-GVHD in two models of disease induction. Thus, blockade of CTL generation in PPs might offer new strategies for circumventing a-GVHD.

Donor T cell and host NK depletion improve the therapeutic efficacy of allogeneic bone marrow cell reconstitution in the nonmyeloablatively conditioned tumor-bearing host

Allogeneic bone marrow cell reconstitution of the nonmyeloablatively conditioned host has the advantage that it can be tolerated in suboptimal health conditions. However, the problem of graft versus host disease (GvHD) remains. Also, graft acceptance may become delicate, and HvGD may arise. We report here on advantages/disadvantages of host natural killer (NK) depletion and graft T cell depletion in fully allogeneic, healthy and solid tumor-bearing mice. NK depletion of the "healthy" host improved the survival rate, whereas graft T cell depletion was disadvantageous. In the tumor-bearing host, graft T cell depletion was beneficial when the host was NK-depleted. Host NK depletion facilitated B lymphopoiesis, repopulation of the thymus, expansion of donor cells, and tolerance induction. The disadvantage of graft T cell depletion in the "healthy" host was a result of delayed engraftment. Because in tumor-bearing mice, host but not graft hematopoiesis was strongly impaired, donor hematopoiesis dominated. Graft T cell depletion reduced GvHD but hardly interfered with engraftment. Importantly, graft-mediated tumor reactivity appeared late and was unimpaired when the graft was T cell-depleted. Thus, concomitant depletion of host NK and donor T cells is advantageous when approaching therapeutic treatment of solid tumors by allogeneic reconstitution of the nonmyeloablatively conditioned host.

Regulation of alloimmune responses (GvH reactions) in vitro by autologous donor bone marrow cell preparation used in clinical organ transplantation

BACKGROUND

Cadaver donor bone marrow cells (DBMC) are capable of a low-grade response to allogeneic stimulation in vitro, indicating their potential ability to cause graft versus host disease (GvHD). However, at this center, we have observed a lack of GvHD in kidney transplant recipients who received DBMC perioperatively. Therefore, we questioned whether an intrinsic immunoregulatory function of (subpopulations of) DBMC might play a role in this observation.

METHODS

In in vitro assays, DBMC was added to autologous splenic responder cells taking part in allogeneic mixed lymphocyte reaction (MLR) and cell-mediated lympholysis (CML) reactions.

RESULTS

When compared with autologous donor irradiated spleen cells as control modulators, DBMC significantly inhibited the CML, but to a much lesser extent than MLR, of autologous responding cells stimulated with allogeneic irradiated cells in a dose dependent manner. The down-regulation of CML responses was observed even in the presence of pharmacological concentrations FK506, mycophenolic acid, or cyclosporine-A. The inhibition could not be overcome by the addition of exogenous helper factors. Moreover, in contrast with findings previously reported from this laboratory of the in vitro inhibitory effect of DBMC on allogeneic responding cells in MLR and CML reactions to stimulating cells of the DBMC donor (allogeneic host versus graft inhibition), the following unique observations were made using DBMC inhibiting autologous reactions (GvH): (1) optimal restimulation of autologous responder cells in secondary cultures could not abrogate this inhibition; even activated responder cells could be inhibited by autologous DBMC, and (2) soluble factors were at least partially operative in this autologous (GvH) inhibition as indicated by experiments in transwells and by the CML inhibition caused by 50% supernatants from DBMC cultures.

CONCLUSION

These in vitro results indicate that DBMC treatment brings about a marked down-regulation of autologous immunocompetent cells in cytotoxicity reactions, partially at least through secreted soluble factor(s), (and in presence of immunosuppressive drugs in vivo) thereby preventing overt clinical GvHD.

The role of hematopoietic stem cells in the treatment of ovarian cancer

In recent years hematopoietic stem cells (HSC) have been the object of new research efforts and scientific advances. Therapeutic strategies have been set up using HSC for the treatment of solid tumors such as ovarian cancer. In this context different approaches have been proposed and clinically investigated. The "autologous" approach refers to the use of HSC as hematologic support to high-dose chemotherapy regimens, and to the use of HSC as an abundant source of dendritic cells for cancer vaccination protocols. Our institution has developed a long-term experience in high-dose chemotherapy with autologous HSC transplantation as first-line treatment of advanced ovarian cancer, and in the use of cytokines both for the HSC collection and for the post-transplantation hematopoietic recovery. Moreover, the "allogeneic" approach with HSC consists of the allogeneic transplantation with both myeloablative/standard or nonmyeloablative/reduced conditioning regimens, which has been proposed as a new adoptive immunotherapeutic treatment for different nonhematologic malignancies. Perspectives in the use of HSC in oncology comprise the possibility of an HSC ex vivo expansion, the use of umbilical cord blood HSC, and the development of future HSC-based gene-therapy programs.

Minor H antigens: genes and peptides

In this review, we describe the evidence from which the existence of non-MHC histocompatibility (H) antigens was deduced, the clinical setting of bone marrow transplantation in which they are important targets for T cell responses, and the current understanding of their molecular identity. We list the peptide epitopes, their MHC restriction molecules and the genes encoding them, of the human and murine minor H antigens now identified at the molecular level. Identification of the peptide epitopes allows T cell responses to these antigens following transplantation of MHC-matched, minor H-mismatched tissues to be enumerated using tetramers and elispot assays. This will facilitate analysis of correlations with HVG, GVH and GVL reactions in vivo. The potential to use minor H peptides to modulate in vivo responses to minor H antigens is discussed. Factors controlling immunodominance of T cell responses to one or a few of many potential minor H antigens remain to be elucidated but are important for making predictions of in vivo HVG, GVH and GVL responses and tailoring therapy after HLA-matched BMT and DLI.

Portal-venous gas unrelated to mesenteric ischemia

The aim of this study was to report on 8 patients with all different non-ischemic etiologies for portal-venous gas and to discuss this rare entity and its potentially misleading CT findings in context with a review of the literature. The CT examinations of eight patients who presented with intrahepatic portal-venous gas, unrelated to bowel ischemia or infarction, were reviewed and compared with their medical records with special emphasis on the pathogenesis and clinical impact of portal-venous gas caused by non-ischemic conditions. The etiologies for portal-venous gas included: abdominal trauma ( n=1); large gastric cancer ( n=1); prior gastroscopic biopsy ( n=1); prior hemicolectomy ( n=1); graft-vs-host reaction ( n=1); large paracolic abscess ( n=1); mesenteric recurrence of ovarian cancer superinfected with clostridium septicum ( n=1); and sepsis with Pseudomonas aeruginosa ( n=1). The clinical outcome of all patients was determined by their underlying disease and not negatively influenced by the presence of portal-venous gas. Although the presence of portal-venous gas usually raises the suspicion of bowel ischemia and/or intestinal necrosis, this CT finding may be related to a variety of non-ischemic etiologies and pathogeneses as well. The knowledge about these conditions may help to avoid misinterpretation of CT findings, inappropriate clinical uncertainty and unnecessary surgery in certain cases.

Minor H antigens: genes and peptides

In this review, we describe the evidence from which the existence of non-MHC histocompatibility (H) antigens was deduced, the clinical setting of bone marrow transplantation in which they are important targets for T-cell responses, and the current understanding of their molecular identity. We list the peptide epitopes of the human and murine minor H antigens now identified at the molecular level, their MHC restriction molecules and the genes encoding them. Identification of the peptide epitopes allows T-cell responses to these antigens following transplantation of MHC-matched, minor H-mismatched tissues to be enumerated using tetramers and elispot assays. This will facilitate analysis of correlations with host-versus-graft (HVG), graft-versus-host (GVH) and graft-versus-leukaemia (GVL) reactions in vivo. The potential to use minor H peptides to modulate in vivo responses to minor H antigens is discussed. Factors controlling immunodominance of T-cell responses to one or a few of many potential minor H antigens remain to be elucidated but are important for making predictions of in vivo HVG, GVH and GVL responses and tailoring therapy after HLA-matched bone marrow transplantation and donor lymphocyte infusion.

Peripheral regulation of graft-versus-host alloreactivity in mixed chimeric miniature swine

BACKGROUND

Despite the presence of circulating donor-derived T cells during the induction of mixed chimerism across MHC barriers in miniature swine, severe graft-versus-host disease was avoided in the majority of animals. In this study, we investigated the possible roles of recipient and donor lymphoid populations in the regulation of donor-anti-recipient alloreactivity.

METHODS

Mixed chimerism across a full MHC-mismatch barrier was established in miniature swine using a high-dose allogeneic peripheral blood stem cell protocol. Peripheral blood mononuclear cells from mixed chimeric swine were co-cultured with naïve donor-matched responders and naïve recipient-matched stimulators in mixed lymphocyte reactions.

RESULTS

Peripheral blood mononuclear cells from mixed chimeras inhibited donor-anti-recipient proliferation. This suppression was radioresistant to 25 Gy. Suppression of donor-anti-recipient alloreactivity was not observed in mixed lymphocyte co-cultures when donor-derived cells were added in the absence of recipient-derived cells.

CONCLUSIONS

These results suggest an association between the presence of an active and relatively radioresistant cell population, demonstrable in vitro, and the regulation of graft-versus-host disease across MHC barriers in mixed chimeric miniature swine.

Immune reconstitution in pediatric stem-cell transplantation

Hematopoietic stem-cell transplantation (HSCT) has successfully been used to cure many pediatric disorders. However, the immunologic alterations associated with transplantation result in profound immunodeficiencies in the transplant recipient, resulting in significant infectious morbidity and mortality. The precarious process of immune reconstitution in the transplant recipient is neither instantaneous nor complete, but influenced by multiple factors such as graft-versus-host disease (GVHD), conditioning regimen, patient age and underlying disease. Studies in pediatric HSCT have revealed unique attributes of immune recovery in pediatric transplant recipients. Future studies addressing these findings are needed to complement novel immunotherapies emerging from the field of transplant immunology.

Lichen planus-like eruption following autologous bone marrow transplantation for chronic myeloid leukaemia

A 47-year-old female treated with an autologous bone marrow transplant and cytotoxic chemotherapy developed a lichen planus-like eruption 12 months later. It involved the skin and oral mucosa, with the histological features of a lichenoid graft-versus-host reaction, including satellite cell necrosis. This eruption developed de novo. The eruption resolved with topical betamethasone valerate 0.1% cream despite the ongoing use of the immunomodulatory agent interferon-alpha2b. Such a reaction in an autologous setting has only been described once previously.

Non-myeloablative hematopoietic stem cell transplantation

Conventional approaches to allogeneic stem cell transplantation have used toxic high-dose conditioning therapy in attempts to eradicate underlying diseases and achieve allogeneic engraftment. Preclinical studies and clinical observations have shown that to achieve engraftment conditioning regimens could be markedly reduced in intensity with reduction in treatment toxicities. The use of potent pre- and postgrafting immunosuppression facilitated stable mixed hematopoietic chimerism in a preclinical canine model. The initial clinical experiences with attenuated conditioning regimens have shown promise as a modality to achieve human stem cell transplantation with an improved safety profile. This may allow offering potentially curative hematopoietic stem cell transplantation (HSCT) to a more representative patient population (older and sicker) who are currently not eligible for such therapy. Obtaining a state of mixed hematopoietic chimerism could prove curative of the disease phenotype of various nonmalignant disturbances of the hematopoietic and immune systems. On the other hand, patients with hematopoietic malignancy will likely require conversion to full donor hematopoeisis by virtue of graft-versus-host (GVH) reactions directed against both recipient hematopoiesis and underlying malignancy. The infusion of additional donor lymphocytes has been proposed by many groups to augment graft versus tumor responses, but most likely more specific strategies will need to be developed to improve efficacy and avoid nonspecific GVH reactions.

Total body irradiation-based regimen in the conditioning of patients submitted to haploidentical stem cell transplantation

BACKGROUND AND PURPOSE

To evaluate the efficacy and toxicity of a highly immuno- and myelo-suppressive conditioning regimen followed by the infusion of large numbers of T-cell-depleted mismatched haematopoietic stem cells in 43 high-risk acute leukaemia patients.

RESULTS

A high rate of engraftment (95%) and no graft-versus-host disease (GvHD) were observed. The 4-year probability of event-free survival was 0.25+/-0.09 for acute myeloid leukaemia and 0.17+/-0.07 for acute lymphoid leukaemia patients.

CONCLUSIONS

This study shows that the main obstacles limiting the use of mismatched transplants, i.e. GvHD and rejection, were overcome.

Bone marrow aplasia induced by passenger leukocytes from heart allografts

OBJECTIVE

Organ allografts contain passenger leukocytes that are transferred to the recipient with the transplantation, but their functional relevance to the recipient's immune system is still controversial.

MATERIALS AND METHODS

To clarify the functional capacity of passenger leukocytes, we attempted to enhance their effect in rat heart allograft recipients by selective depletion of recipient leukocytes using a monoclonal antibody (mAb) against a recipient-specific allotype of CD45 (RT7(a)).

RESULTS

Although antibody treatment of the recipient alone led to profound lymphopenia and reversible myelosuppression, additional transplantation of an major histocompatibility complex-incompatible heart graft from an RT7(b) donor led to lethal aplastic anemia in the recipients. This lethal effect was completely abrogated by postoperative anti-CD3 treatment of the recipient and was partially abrogated or delayed by depletion of passenger leukocytes through additional anti-RT7(b) antibody treatment of the recipient or gamma-irradiation of the graft.

CONCLUSIONS

The results suggest a role for both donor and recipient-type T cells for the induction of aplastic anemia in this model. The study shows that, under defined conditions, allogeneic passenger leukocytes in a heart graft can have a profound effect on the recipient's immune system and bone marrow.

Perichondrial chondrogenesis and periosteal osteogenesis by localized graft-vs-host reaction in mice

Localized GvH reaction produced by the subcutaneous injection of parental lymphoid cells into the ear lobe of F1 recipient mice results in local activation of perichondrial chondrogenesis. Similarly, when the GvH reaction was elicited in shanks, the periosteal membranes at the site of immune reaction were stimulated to proliferate and to produce new bone. However, syngeneic lymphocytes activated in vivo by Con A and untreated syngeneic spleen and bone marrow cells administered locally produced similar response of bone and cartilage. Thus the lymphocytes activated either in the course of GvH reaction or syngeneic lymphocytes grafted into heterotopic sites presumably release mediators capable to stimulate periosteal/perichondrial membranes.

Allogeneic or autologous stem cell transplantation (SCT) for relapsed and refractory Hodgkin's disease and non-Hodgkin's lymphoma: a single-centre experience

PURPOSE OF THE STUDY

The aim of the study was to evaluate which patient might benefit most from allogeneic stem cell transplantation (SCT) in the treatment of relapsed and/or refractory lymphoma.

PATIENTS AND METHODS

Thirty-eight consecutive lymphoma patients receiving either autologous (n = 24) or allogeneic (n = 14) stem cell grafts at our institution from 1986 to 1998 were retrospectively analysed regarding overall survival (OS), disease-free survival (DFS), transplant-related mortality (TRM), and relapse incidence (RI). Uni- and multivariate analyses were performed to identify patient characteristics predictive for outcome after SCT.

RESULTS

The probabilities of OS, DFS, TRM, and relapse were 57%, 51%, 29%, and 30% following autologous and 43%, 43%, 29%, and 38% following allogeneic SCT. Disease status (sensitive versus refractory) and the time interval between diagnosis and SCT were the most powerful predictive parameters for OS and TRM, whereas elevated serum LDH levels were signifcant in determining relapse.

CONCLUSIONS

In patients with elevated serum LDH levels and bone marrow involvement at the time of transplantation allogeneic was superior to autologous SCT and resulted in better outcome due to a lower relapse incidence strongly suggesting the existence of a graft-versus-lymphoma effect.

New strategies for bone marrow transplantation

Adoptive immunotherapy of hematologic malignancies and metastatic solid tumors by donor lymphocyte infusion following induction of host-versus-graft transplantation tolerance against can best be achieved following nonmyeloablative stem-cell transplantation (NST). Induction of mixed chimerism may represent the best approach for induction of transplantation tolerance to donor alloantigens. Thus NST may become the optimal approach for the treatment of nonmalignant diseases, where replacement of host with donor hematopoietic cells is indicated: for correction of genetic or stem cell deficiency diseases; as a platform for immunotherapy of autoimmune or infectious diseases; or for induction of tolerance to organ allografts.