Crucial role of timing of donor lymphocyte infusion in generating dissociated graft-versus-host and graft-versus-leukemia responses in mice receiving allogeneic bone marrow transplants

A murine model of minor histocompatibility antigen-mismatched bone marrow transplantation (BMT) was used to study the role of timing of donor lymphocyte infusion (DLI) in eliciting graft-versus-host (GVH) and graft-versus-leukemia (GVL) reactivity. We gave DLI at weeks 3 and 12 after BMT and related its ability to induce a GVL effect with (1) evolution of T cell chimeric status and (2) the extent to which DLI could elicit lymphohematopoietic GVH (LHGVH) reactivity. All mice remained free of GVH disease, but only week 3 DLI chimeras exhibited a significant GVL response when challenged with host-type leukemia cells. In these week 3 DLI chimeras, host-reactive T cells were found to proliferate in vivo (5- [and-6]-carboxyfluorescein diacetate, succinimidyl esther [CFSE]-labeled DLI inocula, TCR-Vbeta6(+) T-cell frequency) and T-cell chimerism rapidly converted from mixed into complete donor type, indicating the occurrence of LHGVH reactivity. In week 12 chimeras, DLI elicited none of the activities noted at week 3. Yet, in both instances, splenocytes, recovered following DLI, generated an equally strong antihost proliferative response in a mixed lymphocyte reaction, thereby arguing against a decisive role of regulatory cells. The lack of in vivo LHGVH reactivity after week 12 DLI was associated with a substantially increased level of pre-existing host-type T-cell chimerism. We conclude that elicitation of a GVL effect may require LHGVH reactivity and that the reason why timing of DLI was critical for obtaining LHGVH reactivity and the desired GVL effect may lie in the evolution of chimeric status. A possible direct involvement of residual host-type antigen-presenting cells in eliciting LHGVH reactivity after DLI should be studied using models that allow chimerism analysis in non-T-cell lineages.     

Association of natural killer cell immune recovery with a graft-versus-leukemia effect independent of graft-versus-host disease following allogeneic bone marrow transplantation

 There is good evidence that T lymphocytes play an important role in the graft-versus-leukemia (GVL) effect following allogeneic bone marrow transplantation (BMT) for hematologic malignancies. However, the role of natural killer (NK) cells in GVL is less clear. To further investigate a possible association of NK cells with GVL we studied 15 patients undergoing BMT for chronic myeloid leukemia (CML), correlating T-cell (CD4+ and CD8+) and NK-cell (CD16+56+) recovery with relapse and graft-versus-host disease (GVHD). Patients were studied on three occasions up to 9 months after BMT, for lymphocyte surface phenotype and for spontaneous and IL-2-stimulated (LAK cell) cytotoxic function. Circulating CD8+ and NK but not CD4+ cell numbers were significantly lower in five patients who relapsed compared with those remaining in remission after BMT (mean 0.03 vs 0.32×10⁹/l, p=0.002 for CD8+ cells; mean 0.03 vs 0.11×10⁹/l, p=0.002 for NK cells). There was no correlation of CD4+, CD8+, or NK cell numbers and development of grade-II or more acute GVHD. Spontaneous NK cytotoxic function rose to within the normal range in the first month after BMT. LAK function remained low during the study period. These results link NK cell recovery more closely with a GVL than with a GVH effect. Received: 1 May 1996/Accepted: 19 September 1996     

Chemotherapy and granulocyte colony stimulating factor-mobilized blood cell infusion followed by interferon-alpha for relapsed malignancy after allogeneic bone marrow transplantation

Background: Interferon‐α (IFN) is known to promote graft‐versus‐host disease (GVHD) after allogeneic bone marrow transplantation (allo BMT). This property may also be used to enhance a graft‐versus‐leukaemia effect (GVL) after donor leucocyte infusion (DLI), a mode of therapy increasingly offered to patients relapsing after allo BMT. Aim: The aims of the present study were to examine the efficacy and toxicity of IFN therapy administered after granulocyte colony‐stimulating factor (G‐CSF)‐stimulated blood cells given as DLI in patients with acute myeloid leukaemia (AML), chronic myeloid leukaemia (CML), acute lymphoblastic leukaemia (ALL), acute undifferentiated leukaemia (AUL) and multiple myeloma relapsing after allo BMT. Methods: Between October 1996 and September 1999, 27 patients (16 AML, four ALL, three CML, three multiple myeloma, one AUL) who relapsed after allo BMT were treated with chemotherapy followed by DLI, collected after G‐CSF stimulation in all but two cases. Subsequently, IFN was given to patients without significant GVHD or rapidly progressive disease. The outcome after DLI with regard to remission rate, disease‐free survival and GVHD was analysed. Results: Eighteen patients received IFN following DLI, 14 of whom developed significant GVHD (grade II–IV acute or extensive chronic); thereafter, GVHD resolved with cessation of IFN alone in four patients, but 10 required systemic immunosuppression. Twenty‐three patients were given chemotherapy and DLI as initial treatment of relapse; 10 achieved complete remission (CR), in four patients this was only after the onset of GVHD. The other four patients received chemotherapy and DLI as a consolidation of a chemotherapy‐induced remission. The CR was durable only in patients with CML (3 of 3) and AML (4 of 8). Conclusions: Treatment with IFN induced GVHD in the majority of patients receiving DLI. The induction of GVHD and GVL by this approach produced excellent results in patients with CML and modest results in AML, but appeared to be less effective in myeloma and ALL. (Intern Med J 2001; 31: 15–22)     

Donor lymphocyte infusions mediate superior graft-versus-leukemia effects in mixed compared to fully allogeneic chimeras: a critical role for host antigen-presenting cells

In mice, donor leukocyte infusion (DLI) given to established mixed allogeneic chimeras can mediate powerful graft-versus-host (GVH) reactions confined to the lymphohematopoietic system without inducing graft-versus-host disease (GVHD). In a clinical trial attempting to capture this approach to achieve graft-versus-leukemia/lymphoma (GVL) effects without GVHD, we have observed surprisingly powerful antitumor effects of DLI in patients achieving mixed chimerism after nonmyeloablative bone marrow transplantation. This observation led us to hypothesize that host antigen-presenting cells in mixed chimeras might be required to optimally present recipient antigens to the donor lymphocytes, leading to maximal graft-versus-tumor effects. To test this hypothesis, we established mixed and fully allogeneic hematopoietic chimeras in B6 mice and evaluated the effect of DLI on EL4 T-cell lymphoma. DLI administration to mixed chimeras produced dramatically improved leukemia-free survival compared to administration of DLI to full donor chimeras. DLI also converted mixed chimeras to full chimeras without causing GVHD. The magnitude of the GVL effect was dependent on the level of major histocompatibility complex class I expression on recipient hematopoietic cells in mixed chimeras. Thus, the induction of mixed chimerism followed by delayed DLI provides an approach to inhibiting GVHD that optimizes GVL effects.     

Granulocyte-colony stimulating factor promotes lung metastasis through mobilization of Ly6G+Ly6C+ granulocytes

Priming of the organ-specific premetastatic sites is thought to be an important yet incompletely understood step during metastasis. In this study, we show that the metastatic tumors we examined overexpress granulocyte-colony stimulating factor (G-CSF), which expands and mobilizes Ly6G+Ly6C+ granulocytes and facilitates their subsequent homing at distant organs even before the arrival of tumor cells. Moreover, G-CSF-mobilized Ly6G+Ly6C+ cells produce the Bv8 protein, which has been implicated in angiogenesis and mobilization of myeloid cells. Anti-G-CSF or anti-Bv8 antibodies significantly reduced lung metastasis. Transplantation of Bv8 null fetal liver cells into lethally irradiated hosts also reduced metastasis. We identified an unexpected role for Bv8: the ability to stimulate tumor cell migration through activation of one of the Bv8 receptors, prokineticin receptor (PKR)-1. Finally, we show that administration of recombinant G-CSF is sufficient to increase the numbers of Ly6G+Ly6C+ cells in organ-specific metastatic sites and results in enhanced metastatic ability of several tumors.     

Contribution of CD4+ and CD8+ T cells to graft-versus-host disease and graft-versus-leukemia reactivity after transplantation of MHC-compatible bone marrow.

A murine model of allogeneic bone marrow (BM) transplantation was used to determine the relative importance of CD4+ and CD8+ T cells in establishing donor T cell chimerism and in the development of graft-versus-host (GVH) and graft-versus-leukemia (GVL) reactivity. Mature donor T cells were essential for complete chimerism when host mice (AKR, H-2k) were conditioned with suboptimal irradiation (9 Gy = LD50). Transplantation of donor BM (B10.BR, H-2k) resulted in mixed chimerism, whereas mice given BM containing additional T cells developed into complete and stable chimeras. Depletion of T cell subsets was associated with an increase in the frequency of mixed chimerism. The incidence of lethal GVHD was dependent on the number of T cells added to the BM inoculum. Ex vivo depletion of CD4+ T cells eliminated GVH-associated mortality. Removal of CD8+ T cells had no effect on overall survival. In contrast to the GVH results, removal of either CD4+ or CD8+ T cells compromised GVL reactivity, indicating that an optimal GVL response required both CD4+ and CD8+ T cells. T cell-subset depletion did not interfere with the induction of donor-host tolerance in these chimeras and may have facilitated its development. The loss of GVH/GVL effector cells as a result of T cell depletion and the development of donor-host tolerance may act synergistically to prevent or suppress GVH and GVL reactivity.     

In vitro separation of host specific graft-versus-host and graft-versus-leukemia cytotoxic T cell activities.

The association of graft-versus-host disease (GVHD) with lower relapse rates following allogeneic bone marrow transplantation (BMT) in humans led us to analyse post HLA-identical BMT derived anti-host cytotoxic T cells (CTL) for their putative anti-leukemic activity. To establish whether graft-versus-host (GVH) and graft-versus-leukemia (GVL) activities are separate, CTL lines were generated at different time points post-BMT from three patients suffering from acute GVHD. These CTL lines, which exhibited lysis of host normal lymphocytes and neoplastic cells, were analysed at the clonal level. Three functionally different types of clones were characterized: clones directed at host specific minor Histocompatibility (mH) antigens which are shared by patient's peripheral blood lymphocytes (PBL) and leukemic cells; clones recognizing only host PBL but not host leukemic cells; and putative GVL clones directed at patient's neoplastic cells only. These data could explain the long controversies on dissection of GVH and GVL activities. Our results demonstrate that GVH and GVL activities can be dissected, while non-separable effector cells which exhibit both activities do exist as well.     

Generation of CD4+ cytotoxic T-lymphocyte clones from a patient with severe graft-versus-host disease after allogeneic bone marrow transplantation: implications for graft-versus-leukemia reactivity

HLA-identical bone marrow transplantation (BMT) is associated with both graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) reactivity. Different T-cell subsets from the bone marrow (BM) graft may be responsible for GVHD and GVL reactivity after BMT. In the etiology of GVHD, not only CD8+ but also CD4+ donor T lymphocytes may play an important role. Here we report a patient with chronic myeloid leukemia (CML) who was transplanted with the BM from his HLA- genotypically identical sister. After BMT there was complete engraftment, but the patient died because of acute GVHD grade III-IV in complete remission. Cytotoxic T-lymphocyte (CTL) lines were generated after BMT using the irradiated leukemic cells from the patient as stimulator cells and the donor-originated peripheral blood mononuclear cells, procured from the patient after BMT, as responder cells. The generated CTL lines showed specific lysis of the recipient lymphocytes and leukemic cells in a 51Cr release assay. Two types of CTL clones could be established from these CTL lines, both phenotypically CD4+. Clone type I showed male-specific HLA-DQ5-restricted lysis of the recipient lymphocytes, but not of the circulating relatively mature leukemic cells from the patient. This may be explained by the low HLA- DQ5 expression of the more mature CML cells. Clone type II showed HLA- DR2-restricted minor histocompatibility antigen-specific lysis of the recipient lymphocytes and leukemic cells. Both types of CTL clones showed antigen-specific cell-mediated growth inhibition of the recipient clonogenic leukemic precursor cells. These CD4+ CTL clones produced several activating cytokines including tumor necrosis factor alpha, interferon gamma, granulocyte-macrophage colony-stimulating factor (GM-CSF), and macrophage CSF. Our results illustrate that these CD4+ CTL clones may have induced GVHD directly by cytolysis and indirectly by activating cytokines. Because both types of CTL clones recognized the recipient leukemic progenitor cells, they may also contribute to GVL reactivity after BMT.     

Impact of pretransplant conditioning and donor T cells on chimerism, graft-versus-host disease, graft-versus-leukemia reactivity, and tolerance after bone marrow transplantation

Graft rejection, mixed chimerism, graft-versus-host disease (GVHD), leukemia relapse, and tolerance are interrelated manifestations of immunologic reactivity between donor and host cells that significantly affect survival after allogeneic bone marrow transplantation (BMT). In this report, a mouse model of BMT, in which the donor and host were compatible at the major histocompatibility complex (MHC), was used (1) to examine the interrelationship of pretransplant conditioning and T-cell content of donor BM with regard to lymphoid chimerism and GVHD and (2) to determine how these factors affected graft-versus-leukemia (GVL) reactivity and donor-host-tolerance. AKR (H-2k) host mice were administered optimal or suboptimal total body irradiation (TBI) as pretransplant conditioning followed by administration of BM cells from B10.BR (H-2k) donor mice with or without added spleen cells as a source of T lymphocytes. Transplanted mice were injected with a supralethal dose of AKR leukemia cells 20 and 45 days post-BMT to assess GVL reactivity in vivo. The pretransplant conditioning of the host and T-cell content of the donor marrow affected the extent of donor T-cell chimerism and the severity of GVH disease. GVL reactivity was dependent on transplantation of mature donor T cells and occurred only in complete chimeras. Transplantation of T-cell-deficient BM resulted in the persistence of host T cells, ie, incomplete donor T-cell chimerism, even when lethal TBI was used. Mixed chimerism was associated with a lack of GVL reactivity, despite the fact that similar numbers of donor T cells were present in the spleens of mixed and complete chimeras. In this model, moderate numbers of donor T cells facilitated complete donor T-cell engraftment, caused only mild GVHD, and provided a significant GVL effect without preventing the subsequent development of tolerance after conditioning with suboptimal TBI. In contrast, severe, often lethal, GVHD developed when the dose of TBI was increased, whereas tolerance and no GVH/GVL reactivity developed when the T-cell content of the marrow was decreased.     

Distinct graft-versus-leukemic stem cell effects of early or delayed donor leukocyte infusions in a mouse chronic myeloid leukemia model

Among hematologic neoplasms, chronic myeloid leukemia (CML) is exquisitely sensitive to graft-versus-leukemia (GVL) because patients relapsing after allogeneic hematopoietic stem-cell transplantation (alloHSCT) can be cured by donor leukocyte infusion (DLI); however, the cellular mechanisms and strategies to separate GVL from GVHD are unclear. We used a BCR-ABL1 transduction/transplantation mouse model to study the mechanisms of DLI in MHC-matched, minor histocompatibility antigen-mismatched allogeneic chimeras with CML-like leukemia, in which DLI can be administered at the time of transplantation (early) or after recovery of hematopoiesis (delayed). After early DLI, CML-like leukemia cannot be transferred into immunocompetent secondary recipients as soon as 4 days after primary transplantation, demonstrating that cotransplantation of T lymphocytes blocks the engraftment of BCR-ABL1-transduced stem cells. In contrast, in allogeneic chimeras with established CML-like leukemia, combined treatment with delayed DLI and the kinase inhibitor imatinib eradicates leukemia with minimal GVHD. The GVL effect is directed against minor histocompatibility antigens shared by normal and leukemic stem cells, and is mediated predominantly by CD8+ T cells, with minor contributions from CD5- splenocytes, including natural killer cells. These results define a physiologic model of adoptive immunotherapy of CML that will be useful for investigating the cellular and molecular mechanisms of GVL.     

Host MHC class II+ antigen-presenting cells and CD4 cells are required for CD8-mediated graft-versus-leukemia responses following delayed donor leukocyte infusions

Following bone marrow transplantation, delayed donor leukocyte infusions (DLIs) can induce graft-versus-leukemia (GVL) effects without graft-versus-host disease (GVHD). These antitumor responses are maximized by the presence of host hematopoietic antigen-presenting cells (APCs) at the time of DLI. Using a tumor-protection model, we demonstrate here that GVL activity following administration of DLIs to established mixed chimeras is dependent primarily on reactivity to allogeneic MHC antigens rather than minor histocompatibility or tumor-associated antigens. CD8(+) T-cell-dependent GVL responses against an MHC class II-negative tumor following delayed DLI require CD4(+) T-cell help and are reduced significantly when host APCs lack MHC class II expression. CD4(+) T cells primed by host APCs were required for maximal expansion of graft-versus-host reactive CD8(+) T cells but not their synthesis of IFN-gamma. In contrast, the GVL requirement for CD4(+) T-cell help was bypassed almost completely when DLI was administered to freshly irradiated recipients, indicating that the host environment is a major factor influencing the cellular mechanisms of GVL.     

Interferon-gamma suppresses T-cell proliferation to mitogen via the nitric oxide pathway during experimental acute graft-versus-host disease

The development of graft-versus-host disease (GVHD) is associated with long-lasting and profound deficits in immune function that lead to increased morbidity and mortality after bone marrow transplantation (BMT). We investigated a mechanism of T-cell immunodeficiency in response to mitogen or alloantigen in an experimental model of acute GVHD by analyzing the roles of two immunosuppressive moieties: interferon gamma (IFN-gamma) and nitric oxide (NO). Splenocytes from mice with GVHD did not proliferate either to the T-cell mitogen, concanavalin A (Con A), or to host alloantigens, but only mitogen- activated cultures produced increased levels of NO. The abrogation of NO synthesis with LG-mono-methyl-arginine (NMMA) restored mitogen- induced proliferation but not the response to host antigens. The mechanism of impared proliferation to mitogen was dependent on IFN- gamma because blockade of this cytokine in culture inhibited NO production and restored proliferation to Con A to levels similar to those in transplanted control mice without GVHD. NMMA did not substantially reduce IFN-gamma levels, demonstrating that NO acted distally to IFN-gamma in the pathway of immunosuppression in response to mitogen. Furthermore, the prevention of IFN-gamma production in vivo after allogeneic BMT, by transplantation of polarized type 2 donor T cells (secreting interleukin-4 but not IFN-gamma), also prevented NO production and restored splenocyte responses to mitogen. Our data demonstrate the existence of NO-dependent and NO-independent pathways involved in suppression of T-cell proliferation during acute GVHD. Excess NO synthesis appears to be one mechanism by which IFN-gamma induces immunodeficiency after allogeneic BMT.     

Donor T cell-derived TNF is required for graft-versus-host disease and graft-versus-tumor activity after bone marrow transplantation

Previous studies in murine bone marrow transplantation (BMT) models using neutralizing anti-tumor necrosis factor (TNF) antibodies or TNF receptor (TNFR)-deficient recipients have demonstrated that TNF can be involved in both graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL). TNF in these GVHD and GVL models was thought to be primarily produced by activated monocytes and macrophages, and the role of T cell-derived TNF was not determined. We used TNF(-/-) mice to study the specific role of TNF produced by donor T cells in a well-established parent-into-F1 hybrid model (C57BL/6J-->C3FeB6F1/J). Recipients of TNF(-/-) T cells developed significantly less morbidity and mortality from GVHD than recipients of wild-type (wt) T cells. Histology of GVHD target organs revealed significantly less damage in thymus, small bowel, and large bowel, but not in liver or skin tissues from recipients of TNF(-/-) T cells. Recipients of TNF(-/-) T cells which were also inoculated with leukemia cells at the time of BMT showed increased mortality from leukemia when compared with recipients of wt cells. We found that TNF(-/-) T cells do not have intrinsic defects in vitro or in vivo in proliferation, IFN-gamma production, or alloactivation. We could not detect TNF in the serum of our transplant recipients, suggesting that T cells contribute to GVHD and GVL via membrane-bound or locally released TNF.     

Histone deacetylase inhibitor suberoylanilide hydroxamic acid reduces acute graft-versus-host disease and preserves graft-versus-leukemia effect

Acute graft-versus-host disease (GVHD) and leukemic relapse are the two major obstacles to successful outcomes after allogeneic bone marrow transplantation (BMT), an effective therapy for hematological malignancies. Several studies have demonstrated that the dysregulation of proinflammatory cytokines and the loss of gastrointestinal tract integrity contribute to GVHD, whereas the donor cytotoxic responses are critical for graft-versus-leukemia (GVL) preservation. Suberoylanilide hydroxamic acid (SAHA) is currently in clinical trials as an antitumor agent; it inhibits the activity of histone deacetylases and at low doses exhibits antiinflammatory effects by reducing the production of proinflammatory cytokines. Using two well characterized mouse models of BMT, we have studied the effects of SAHA on GVHD severity and GVL activity. Administration of SAHA from day +3 to day +7 after BMT reduced serum levels of the proinflammatory cytokines and decreased intestinal histopathology, clinical severity, and mortality from acute GVHD compared with vehicle-treated animals. However, SAHA had no effect on donor T cell proliferative and cytotoxic responses to host antigens in vivo or in vitro. When mice received lethal doses of tumor cells at the time of BMT, administration of SAHA did not impair GVL activity and resulted in significantly improved leukemia-free survival by using two different tumor and donor/recipient combinations. These findings reveal a critical role for histone deacetylase inhibition in the proinflammatory events contributing to GVHD and suggest that this class of pharmacologic agents may provide a strategy to reduce GVHD while preserving cytotoxic T cell responses to host antigens and maintaining beneficial GVL effects.     

T-cell--depleted allogeneic bone marrow transplantation followed by donor lymphocyte infusion in patients with multiple myeloma: induction of graft-versus-myeloma effect

Previous trials of allogeneic bone marrow transplantation (BMT) in patients with multiple myeloma (MM) have demonstrated high response rates but also high transplantation-related mortality (TRM) and high relapse rates. Exploitation of this strategy remains of interest because donor lymphocyte infusions (DLIs) can induce a potent graft-versus-myeloma (GVM) effect. CD6 T-cell--depleted allogeneic BMT was combined with prophylactic CD4(+) DLI administered 6 to 9 months after BMT in an effort to reduce TRM and to induce a GVM response after BMT. Twenty-four patients with matched sibling donors and chemotherapy-sensitive disease underwent BMT. CD6 T-cell depletion of donor bone marrow was the sole method of graft-versus-host disease (GVHD) prophylaxis. GVHD after BMT was minimal, 1 (4%) grade III and 4 (17%) grade II GVHD. Fourteen patients received DLI, 3 in complete response and 11 with persistent disease after BMT. Significant GVM responses were noted after DLI in 10 patients with persistent disease, resulting in 6 complete responses and 4 partial responses. After DLI, 50% of patients developed acute (> or = II) or extensive chronic GVHD. Two-year estimated overall survival and current progression-free survival (PFS) for all 24 patients is 55% and 42%, respectively. The 14 patients receiving DLI had an improved 2-year current PFS (65%) when compared with a historical cohort of MM patients who underwent CD6-depleted BMT survived 6 months with no GVHD and did not receive DLI (41%) (P =.13). Although this study suggests that prophylactic DLI induces significant GVM responses after allogeneic BMT, only 58% of patients were able to receive DLI despite T-cell--depleted BMT. Therefore, less toxic transplantation strategies are needed to allow a higher proportion of patients to receive DLI and the benefit from the GVM effect after transplantation. (Blood. 2001;98:934-939)     

Dynamics in chimerism of T cells and dendritic cells in relapsed CML patients and the influence on the induction of alloreactivity following donor lymphocyte infusion

Donor lymphocyte infusion (DLI) after allogeneic SCT induces complete remissions in approximately 80% of patients with relapsed CML in chronic phase, but some patients do not respond to DLI. We studied absolute numbers of dendritic cell (DC) subsets and chimerism in T cells and two subsets of blood DCs (myeloid DCs (MDCs) and plasmacytoid DCs (PDCs)) in relation to DLI-induced alloreactivity. Based on T cell and DC chimerism, we identified three groups. Four patients were completely donor chimeric in T cells and DC subsets. These patients had an early stage of relapse, and three of the four patients attained complete molecular remission (CMolR) without significant GVHD. Six patients were completely donor in T cells and mixed chimeric in DC subsets. All patients entered CMolR, but this was associated with GVHD in four and cytopenia in three patients. Five patients had mixed chimerism in T cells and complete recipient chimerism in MDC; only two patients entered CMolR. Our data suggest that the combination of donor T cells and mixed chimerism in DC subsets induces a potent graft-versus-leukemia (GVL) effect in association with GVHD. DLI in patients with an early relapse and donor chimerism in both T cells and DC subsets results in GVL reactivity without GVHD.     

Separation of antileukemic effects from graft-versus-host disease in MHC-haploidentical murine bone marrow transplantation: participation of host immune cells

Allogeneic hematopoietic stem cell transplantation (HSCT) is associated with both graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) effects. In clinical studies of HLA-mismatched HSCT, strong GVL effects have been reported. In the present study, we addressed the mechanism of the GVL and GVH response using MHC-haploidentical murine bone marrow transplantation (BMT) models. Recipient BDF1 (H-2^b/d) mice received T cell-depleted bone marrow and spleen cells from B6C3F1 (H-2^b/k) or C57BL/6 (H-2^b) mice with or without P815 mastocytoma cells (H-2^d) after receiving lethal total body irradiation. B6C3F1 → BDF1 (hetero-to-hetero type) recipients showed more powerful antileukemic effects with less severe GVHD than C57BL/6 → BDF1 (parent-to-F1 type) recipients. Compared with C57BL/6 → BDF1 recipients, significantly higher in vitro cytotoxic activity against P815 cells was observed in B6C3F1 → BDF1 recipients. Significantly lower CXCR3 expression on donor T cells and higher interferon (IFN)-γ expression were considered to be associated with strong antileukemic effects with less severe GVHD in B6C3F1 → BDF1 recipients. Furthermore, host immune cells, especially natural killer cells and CD8⁺ T cells, were found to contribute remarkably to high IFN-γ production in B6C3F1 → BDF1 recipients. Thus, in MHC-haploidentical HSCT, host immune cells may change the balance between GVH and GVL response through IFN-γ production.     

Pre-emptive immunotherapy with CD8-depleted donor lymphocytes after CD34-selected allogeneic peripheral blood stem cell transplantation.

BACKGROUND AND OBJECTIVES: To maximize graft-versus-leukemia (GVL) effects while minimizing the risk of graft-versus-host disease (GVHD), we undertook a study of allogeneic CD34-selected peripheral blood stem cell (PBSC) transplantation followed by CD8-depleted donor lymphocyte infusion (DLI). DESIGN AND METHODS: Twenty-four patients with advanced hematologic malignancies were included. PBSC were collected in matched (N=16) or one-mismatch (N=8) related donors and CD34-selected. On day 60, donors donated lymphocytes that were CD8-depleted and separated into 3 aliquots containing 2 x 10(6), 1 x 10(7) and 5 x 10(7) CD3+ cells/kg (patients 1-13) or into 2 aliquots containing 1 x 10(7) and 5 x 10(7) CD3+ cells/kg (patients 14-24). The 1st aliquot was infused on day 60 and the other 1 (2) cryopreserved and infused on days 100 (and 140). RESULTS: An average of 100%, 100% and 84% of the scheduled dose could be administered in DLI 1, 2 and 3, respectively. Although the study group was at very high risk of GVHD, the actuarial incidence of grade II-IV acute GVHD was 28% (13% for HLA-identical siblings) with only 1 patient developing grade III-IV GVHD (after DLI). The actuarial 2-year probability of extensive chronic GVHD was similarly low (13% for all patients and 0% for HLA-identical siblings). Individual cases as well as a 30% relapse rate (0% for standard-risk patients versus 55% for high-risk patients) indicated preservation of the GVL effect. INTERPRETATION AND CONCLUSIONS: We conclude that allogeneic transplantation of CD34-selected PBSC followed by pre-emptive CD8-depleted DLI is feasible with rapid engraftment and minimizes the risk of severe GVHD. Large prospective trials are required to prove that it preserves the GVL effect fully.     

Interleukin 18 preserves a perforin-dependent graft-versus-leukemia effect after allogeneic bone marrow transplantation

We have recently shown that early administration of interleukin 18 (IL-18) after bone marrow transplantation (BMT) attenuates acute graft-versus-host disease (GVHD) in a lethally irradiated parent into F1 (B6-->B6D2F1) BMT model. In this study, we investigated whether IL-18 can maintain graft-versus-leukemia (GVL) effect in this context. B6D2F1 mice received transplants of T-cell-depleted (TCD) bone marrow (BM) and splenic T cells from either syngeneic (H2(b/d)) or allogeneic B6 (H2(b)) donors. Recipient mice were treated with recombinant murine IL-18 or the control diluent. Initial studies demonstrated that IL-18 treatment did not affect the proliferative responses or the cytolytic effector functions of T cells after BMT. In subsequent experiments, animals also received host-type P815 mastocytoma cells at the time of BMT. All syngeneic BM transplant recipients died from leukemia by day 18. The allogeneic BM transplant recipients effectively rejected their leukemia regardless of treatment and IL-18 significantly reduced GVHD-related mortality. Examination of the cytotoxic mechanisms with perforin-deficient donor T cells demonstrated that perforin is critical for the GVL effect. Taken together these data demonstrate that IL-18 can attenuate acute GVHD without impairing the in vitro cytolytic function or the in vivo GVL activity after allogeneic BMT.