Durable graft‐versus‐leukaemia effects without donor lymphocyte infusions – results of a phase II study of sequential T‐replete allogeneic transplantation for high‐risk acute myeloid leukaemia and myelodysplasia

Allogeneic haematopoietic stem‐cell transplantation remains the only curative treatment for relapsed/refractory acute myeloid leukaemia (AML) and high‐risk myelodysplasia but has previously been limited to patients who achieve remission before transplant. New sequential approaches employing T‐cell depleted transplantation directly after chemotherapy show promise but are burdened by viral infection and require donor lymphocyte infusions (DLI) to augment donor chimerism and graft‐versus‐leukaemia effects. T‐replete transplantation in sequential approaches could reduce both viral infection and DLI usage. We therefore performed a single‐arm prospective Phase II clinical trial of sequential chemotherapy and T‐replete transplantation using reduced‐intensity conditioning without planned DLI. The primary endpoint was overall survival. Forty‐seven patients with relapsed/refractory AML or high‐risk myelodysplasia were enrolled; 43 proceeded to transplantation. High levels of donor chimerism were achieved spontaneously with no DLI. Overall survival of transplanted patients was 45% and 33% at 1 and 3 years. Only one patient developed cytomegalovirus disease. Cumulative incidences of treatment‐related mortality and relapse were 35% and 20% at 1 year. Patients with relapsed AML and myelodysplasia had the most favourable outcomes. Late‐onset graft‐versus‐host disease protected against relapse. In conclusion, a T‐replete sequential transplantation using reduced‐intensity conditioning is feasible for relapsed/refractory AML and myelodysplasia and can deliver graft‐versus‐leukaemia effects without DLI.     

Mixed chimera converted into full donor chimera with powerful graft-versus-leukemia effects but no graft-versus-host disease after non T cell-depleted HLA-mismatched peripheral blood stem cell transplantation

Instead of donor T cell depletion, we used CTLA4 and TJU103 (a small organic compound believed to block CD4 binding to MHC II molecule of APC) to block donor T lymphocyte activation in vitro before infusion, and mycophenolate mofetil to control the activity of lymphocytes of the recipient. We successfully treated a patient with an HLA-mismatched graft without donor T cell depletion. Mixed chimerism was observed 30 days and 60 days after transplantation. STR-PCR showed that 28% and 62% of blood mononuclear cells (MNC) were donor derived at day +30 and day +60, respectively. Mixed chimerism converted into full donor chimerism, when 99.7% of the MNC in the recipient were donor derived after three courses of DLI. A powerful GVL effect related to mixed chimerism was observed. No acute GVHD occurred, only grade II chronic GVHD occurred 6 months after transplant. Based on this case, we suggest that: (1) stable mixed chimerism can be intentionally established across HLA barriers without donor T cell depletion; (2) mixed chimerism can be converted into full donor chimerism by DLI; (3) mixed chimerism induced with this approach can be associated with a very powerful GVL effect, and these may be enhanced by DLI, without severe GVHD.     

Graft-versus-host-reactive donor CD4 cells can induce T cell-mediated rejection of the donor marrow in mixed allogeneic chimeras prepared with nonmyeloablative conditioning

Murine mixed hematopoietic chimerism can be achieved following nonmyeloablative conditioning with cyclophosphamide, T cell-depleting monoclonal antibodies, and thymic irradiation. Donor lymphocyte infusions (DLIs) 35 days after bone marrow transplantation (BMT) convert mixed to full donor chimerism and mediate graft-versus-lymphoma effects without graft-versus-host disease. We evaluated the role of T-cell subsets in DLIs in converting mixed to full donor chimerism in a fully major histocompatibility complex-mismatched strain combination. Whereas DLIs administered on day 35 converted 100% of mixed chimeras to full donor chimerism, conversion was less frequent when either CD4 or CD8 cells were depleted, indicating that both subsets contribute to the conversion. Surprisingly, administration of CD8-depleted DLIs led to complete loss of donor chimerism in a high proportion (54%) of recipients compared with CD4-plus CD8-depleted DLIs (15%) or CD4-depleted DLIs (0%) (P <.05). DLIs administered at early time points after BMT (eg, day 21) also precipitated rejection of donor marrow by recipient alphabeta T cells, in association with donor CD4 cell expansion and high production of interleukin 2 (IL-2), IL-4, and interferon-gamma. Thus, DLIs can paradoxically induce marrow rejection by residual host alphabeta T cells. These results have implications for the timing of and use of subset depletion of DLIs in recipients of nonmyeloablative transplants.     

Mixed chimerism in SCT: conflict or peaceful coexistence?

Stem cell transplants that follow both myeloablative and non-myeloablative conditioning regimens can result in states of mixed chimerism, which can be stable over time. With widespread availability of Y chromosome FISH in sex-mismatched transplantation and DNA-based methodologies for analysis of chimerism in other donor-recipient pairs, further insights have been gained regarding the implications of the mixed chimeric state. In transplants performed for inherited and acquired marrow failure disorders, disease status can be improved with only 10-20% donor cells, and it appears that stable mixed chimerism at that level is an acceptable outcome often leading to a state of tolerance, but an increasing level of recipient cells often precedes graft rejection. In transplants performed for malignant conditions, increasing levels of mixed chimerism may indicate disease relapse, but some cases with stable levels of mixed chimerism have been compatible with prolonged remission states. Understanding when mixed chimerism is an indication of secondary graft failure or impending graft rejection vs a state of tolerance and ongoing propensity for the establishment of a graft-vs-tumor effect is often difficult with currently available technologies and immunologic assays. The ability to understand the implication of mixed chimerism of multiple cell lineages and of varied lymphocyte subsets will remain important areas for future research to best harness the immunologic and other therapeutic benefits of allogeneic transplantation.Bone Marrow Transplantation (2008) 42, 297-310; doi:10.1038/bmt.2008.212; published online 28 July 2008.     

异基因造血干细胞移植后的嵌合状态分析

目的研究异基因外周血造血干细胞移植（allo-PBSCT）后T淋巴细胞和粒细胞嵌合状态与疾病复发、移植物被排斥和移植物抗宿主病（GVHD）等的关系.方法21例HLA完全相合allo-PBSCT患者,流式细胞仪分选出外周血粒细胞、T淋巴细胞,分别进行短串联重复片段（STR）-PCR扩增.结果移植后7 d时17/21例患者T淋巴细胞的植入程度高于粒细胞,供者嵌合比例（DC）分别为60%（15%～76%）和0%（0%～40%）.除去移植后28 d复发且T淋巴细胞一直为混合嵌合（MC）1例,其余20例T淋巴细胞达到完全嵌合（CDC）的中位时间是21（14～102）d,粒细胞为14 d.T淋巴细胞比粒细胞更早植入,但达到CDC的时间较粒细胞晚.7例在疾病复发或移植物被排斥时,T淋巴细胞比粒细胞更早出现DC的下降,其中4例患者仅表现为T淋巴细胞出现DC的下降,而全骨髓细胞和粒细胞仍为CDC或无明显下降,骨髓象检查未见异常.而在减量、停用免疫抑制剂或供者淋巴细胞输注后,治疗有效的4例患者T淋巴细胞逐渐由MC变为CDC,并有3例在转变过程中出现急性GVHD.结论allo-PBSCT后进行白细胞亚群,尤其是T淋巴细胞的嵌合状态检测可以比全血或全骨髓样本更早发现供者细胞的植入、疾病复发或移植物被排斥,及时采取相应的免疫干预措施,提高移植成功率.     

Expansion of recipient‐derived antiviral T cells may influence donor chimerism after allogeneic stem cell transplantation

Donor chimerism (DC) analysis is an important marker in the hematopoietic stem cell transplant follow‐up. Here, we present evidence for a possible relationship of infectious complications and declines in DC. We analyzed the DC in patients experiencing cytomegalovirus (CMV) reactivation. In addition, in some patients chimerism analyses of T‐cell subsets were performed. CMV‐specific cytotoxic T‐lymphocytes (CMV‐CTL) were monitored using human leukocyte antigen‐restricted multimer staining. Interestingly, CMV reactivation was accompanied by changes in DC in 11 of 67 patients transplanted. For example, DC declined in a cord blood recipient, in both total leukocytes and CD4 and CD8 T‐cell subsets upon CMV reactivation. The latter was controlled after only 5 days through expanding CMV‐CTL of 96% recipient origin, according to chimerism analysis of CMV‐CTL (enriched beyond 50%). In another patient, transplanted after reduced‐intensity conditioning from a DQB1 mismatched, CMV seronegative donor, incipient CMV reactivation was completely aborted by CMV‐CTL of recipient origin. However, at the same time, mixed chimerism dropped from 51% to 0% donor type, resulting in late graft rejection. Our data indicate that chimerism analyses in subset populations lead to a better understanding of declining total leukocyte chimerism. Furthermore, recipient‐derived CMV‐CTL may be able to control CMV reactivation after reduced‐intensity conditioning. We speculate that autologous CMV‐CTL may be instrumental to overcome recurrent CMV reactivations, especially in patients transplanted from CMV‐seronegative donors. In addition, the expansion of recipient‐derived CMV‐CTL may contribute to both, graft failure or to conversion to full DC.     

Treatment of graft failure with TNI‐based reconditioning and haploidentical stem cells in paediatric patients

Graft failure is a life‐threatening complication after allogeneic haematopoietic stem cell transplantation (HSCT). We report a cohort of 19 consecutive patients (median age: 8·5 years) with acute leukaemias (n = 14) and non‐malignant diseases (n = 5) who experienced graft failure after previous HSCT from matched (n = 3) or haploidentical donors (n = 16) between 2003 and 2012. After total nodal irradiation (TNI)‐based reconditioning combined with fludarabine, thiotepa and anti‐T cell serotherapy, all patients received T cell‐depleted peripheral blood stem cell grafts from a second, haploidentical donor. Median time between graft failure and retransplantation was 14 d (range 7–40). Sustained engraftment (median: 10 d, range 9–32) and complete donor chimerism was observed in all evaluable patients. 5 patients additionally received donor lymphocyte infusions. Graft‐versus‐host disease (GvHD) grade II and III occurred in 1 patient each (22%); no GvHD grade IV was observed. 2 patients had transient chronic GvHD. The regimen was well tolerated with transient interstitial pneumonitis in one patient. Treatment‐related mortality after one year was 11%. Event‐free survival and overall survival 3 years after retransplantation were 63% and 68%. Thus, a TNI‐based reconditioning regimen followed by transplantation of haploidentical stem cells is an option to rescue patients with graft failure within a short time span and with low toxicity.     

Targeted pretransplant host lymphocyte depletion prior to T-cell depleted reduced-intensity allogeneic stem cell transplantation

Mixed chimaerism and graft rejection are higher after reduced-intensity allogeneic stem cell transplantation (RIST) with T-cell depleted (TCD) allografts. As host immune status before RIST affects engraftment, we hypothesized that targeted depletion of host lymphocytes prior to RIST would abrogate graft rejection and promote donor chimaerism. Lymphocyte-depleting chemotherapy was administered at conventional doses to subjects prior to RIST with the intent of decreasing CD4(+) counts to <0.05 x 10(9)cells/l. Subjects (n = 18) then received reduced-intensity conditioning followed by ex vivo TCD human leucocyte antigen-matched sibling allografts. All evaluable patients (n = 17) were engrafted; there were no late graft failures. At day +28 post-RIST, 12 patients showed complete donor chimaerism. Mixed chimaerism in the remaining five patients was associated with higher numbers of circulating host CD3(+) cells (P = 0.0032) after lymphocyte-depleting chemotherapy and was preferentially observed in T lymphoid rather than myeloid cells. Full donor chimaerism was achieved in all patients after planned donor lymphocyte infusions. These data reflect the importance of host immune status prior to RIST and suggest that targeted host lymphocyte depletion facilitates the engraftment of TCD allografts. Targeted lymphocyte depletion may permit an individualized approach to conditioning based on host immune status prior to RIST.     

Early host CD8 T-cell recovery and sensitized anti-donor interleukin-2-producing and cytotoxic T-cell responses associated with marrow graft rejection following nonmyeloablative allogeneic bone marrow transplantation

OBJECTIVE: We developed a nonmyeloablative conditioning regimen for allogeneic bone marrow transplantation (BMT) followed by donor lymphocyte infusions (DLI) for treatment of chemotherapy refractory malignancies. Although the majority of patients who receive this regimen achieve lasting mixed or full allogeneic chimerism, approximately 30% show initial mixed chimerism followed by loss of the donor graft. These patients recover host hematopoiesis without significant cytopenias. To assess the role of immunologic rejection in graft loss, we compared T-cell recovery and in vitro alloresponses in six patients who lost their marrow graft to that in 16 concurrent patients with sustained donor chimerism. PATIENTS AND METHODS: Conditioning included pretransplant cyclophosphamide (150-200 mg/kg), thymic irradiation (700 cGy), and pre- and post-transplant equine antithymocyte globulin (ATG; ATGAM). HLA-identical related donor BMT was followed by DLI at approximately day 35 in patients without graft-vs-host disease. RESULTS: The group with transient chimerism showed significantly increased circulating host T-cell (median 416 cells/mm(3) vs 10 cells/mm(3), p<0.05) and CD8 T-cell numbers (354 cells/mm(3) vs 71 cells/mm(3), p<0.05) compared to the group with stable mixed or full donor chimerism within the first 100 days post-BMT. All DLI recipients who lost chimerism following DLI had greater than 80% recipient T cells at the time of DLI, whereas those with persistent chimerism had <60% host T cells. Graft rejection was associated with the development of a sensitized anti-donor bulk cytotoxic T-lymphocyte (CTL) response in 4 of 6 evaluated patients, compared to only 1 of 10 evaluated patients with sustained chimerism (p<0.05). Additionally, 3 of 5 evaluated transient chimeras showed high anti-donor CTL precursor frequencies in limiting dilution assays, and 3 of 4 evaluated transient chimeras showed high anti-donor interleukin-2 (IL-2)-producing T-helper (T(H)) cell frequencies. High anti-donor T(H) or cytotoxic T-lymphocyte precursors were not detected in sustained chimeras. CONCLUSION: These data indicate that loss of chimerism in patients receiving this nonmyeloablative regimen is due to immune-mediated rejection. This rejection appears to bemediated by recovering recipient cytolytic CD8(+) cells as well as IL-2-producing recipient T(H) cells. These data are the first to demonstrate sensitization of recipient anti-donor IL-2-producing cells in association with human marrow allograft rejection.     

Recombinant IL‐7/HGFβ hybrid cytokine separates acute graft‐versus‐host‐disease from graft‐versus‐tumour activity by altering donor T cell trafficking

Given that donor T cells from a transplant contribute both the desired graft‐versus‐tumour (GVT) effect and detrimental graft‐versus‐host disease (GVHD), strategies to separate GVHD and GVT activity are a major clinical goal. We have previously demonstrated that in vivo administration of a recombinant (r)IL‐7/HGFβ hybrid cytokine, consisting of interleukin‐7 (IL‐7, IL7) and the β‐chain of hepatocyte growth factor (HGFβ), significantly inhibits the growth of cancer cells in murine tumour models. The antit‐umour effect of rIL‐7/HGFβ is related to a marked infiltration T cells in the tumour tissues. We have also shown that GVHD was not induced in rIL‐7/HGFβ‐treated T cell‐depleted allogeneic haematopoietic stem cell transplantation (HSCT) recipients. We show here that, in T cell‐replete allogeneic HSCT murine models, rIL‐7/HGFβ attenuated acute GVHD (aGVHD), while promoting GVT activity. This was related to an alteration of donor T cell trafficking, with an increased infiltration of donor T cells into tumour tissues and the lympho‐haematopoietic system but decreased number of the T cells in the GVHD target organs. Therefore, rIL‐7/HGFβ may offer a new tool to alleviate aGVHD while prompting GVT, and to study the molecular regulation of T cell trafficking.     

Treosulfan‐based conditioning regimen for allogeneic haematopoietic stem cell transplantation in children with sickle cell disease

Although allogeneic haematopoietic stem cell transplantation (HSCT) still represents the only consolidated possibility of cure for sickle cell disease (SCD) patients, its use has been limited by the risk of morbidity and mortality associated with conventional myeloablative therapy. The introduction of treosulfan to replace busulfan in conditioning regimens has recently been explored by virtue of its lower toxicity profile. We report our experience with a treosulfan/thiotepa/fludarabine conditioning for human leucocyte antigen (HLA)‐matched sibling or unrelated donor‐HSCT in 15 children with SCD, and compare patient outcomes with those of a historical cohort (15 patients) given a busulfan‐based regimen. Engraftment was achieved in 28 out of 30 patients (93%), with one case of graft failure in either group. The conditioning regimen was well tolerated in both groups, with no cases of grade III‐IV regimen‐related toxicity. The 7‐year overall survival (OS) and disease‐free survival (DFS) for the whole cohort were 100% and 93%, respectively, with a 93% DFS in both busulfan and treosulfan groups. No SCD‐related adverse events occurred after engraftment in patients with complete or mixed donor chimerism. This retrospective analysis suggests that a treosulfan‐based conditioning regimen is able to ensure engraftment with excellent OS/DFS and low regimen‐related toxicity in patients with SCD.     

Mixed chimerism and graft failure following conditioning with the fludarabine and cyclophosphamide nonablative regimen; conversion to full donor chimerism

Twenty-one patients with hematologic malignancies were treated with the fludarabine (120-125 mg/m(2)) and cyclophosphamide (120 mg/kg) nonmyeloablative conditioning regimen. Graft versus host disease (GVHD) and graft rejection prophylaxis was with tacrolimus and mycophenolate mofetil. Thirteen of the 21 patients (62%) had mixed chimerism (< or = 90% donor cells) at day 60 and 11 (52%) of these patients had mixed chimerism which persisted until day 100. Immunosuppression was discontinued in 12 of 13 patients and two of them converted to full chimerism by day 100. Eight patients received a donor lymphocyte infusion (DLI) and five of them converted to full donor chimerism with DLI alone. Two patients were given GM-CSF in addition to a DLI with conversion to full donor chimerism. Three patients (14%) had graft failure requiring a second transplant using fludarabine (125 mg/m(2)) and melphalan (140 mg/m(2)). With a median followup of 2.8 years, 15 patients are alive - one with disease and 14 with no disease. Two patients died of acute GVHD, one of chronic GVHD, and three due to progressive disease. We conclude that the nonmyeloablative fludarabine/cyclophosphamide regimen results in a significant incidence of mixed chimerism and graft rejection but is well tolerated. We suggest a more intense regimen, such as fludarabine and melphalan, be used in patients with a high risk of early disease progression to establish early engraftment and graft versus tumor effect.     

Successful T-cell-depleted,related haploidentical peripheral blood stem cell transplantation in a patient with Fanconi anaemia using a fludarabine-based preparative regimen without radiation

Haematopoietic stem cell transplantation (HSCT) represents the treatment of choice for severe bone marrow failure in patients with Fanconi anaemia (FA). When the donor is a compatible relative, the chance of being cured with an allograft is in the order of 70%. However, for FA children lacking an HLA-identical sibling, the results of HSCT from an alternative donor are less satisfactory because of a higher risk of graft rejection, graft-versus-host-disease (GVHD) and regimen-related toxicity. We report on a 12-year-old girl with FA, who was treated by T-cell-depleted (TCD) peripheral blood HSCT from her haploidentical uncle, using a novel fludarabine-based preparative regimen without radiation. She had rapid engraftment with no toxicity and no GVHD. Progressive recovery of both numbers of lymphocyte and of proliferative response to polyclonal activators occurred over time. At 18 months after transplantation, she is well with 100% donor chimerism and has recovered normal immune function.     

Transient familial haemophagocytic lymphohistiocytosis reactivation post-CD34 haematopoietic stem cell transplantation

Familial haemophagocytic lymphohistiocytosis (FHLH) is a genetic disorder caused by defective lymphocyte cytotoxicity, resulting in impaired lymphocyte homeostasis and macrophage infiltration of solid tissues and bone marrow, with extensive haemophagocytosis. It is invariably fatal unless treated by allogeneic haematopoietic stem cell transplantation (HSCT). In a retrospective analysis of 11 cases of FHLH, transplanted in one centre between January 1999 and December 2003, it was found that host T cell expansion occurred early after HSCT in a setting of a viral infection (cytomegalovirus and Epstein-Barr virus respectively) in two cases who received T cell-depleted HSCT. Transient recurrence of clinical and biological manifestations of FHLH was observed, despite evidence for donor cell engraftment. Secondary development of donor T cells led to stable mixed chimaerism and sustained remission of FHLH. Detection of host-derived T cells soon after HSCT in a patient with FHLH should thus not mistakenly be taken as a manifestation of graft rejection.     

Clinical relevance of recipient leukocyte infusion as antitumor therapy following nonmyeloablative allogeneic hematopoietic cell transplantation

OBJECTIVE: Graft-versus-leukemia effects of donor lymphocytes have been considered to be central to the therapeutic benefit of nonmyeloablative allogeneic hematopoietic cell transplantation (HCT) for malignant diseases. Surprisingly, some patients who reject donor grafts following nonmyeloablative HCT have sustained remissions of advanced, chemorefractory hematologic malignancies. In murine mixed chimeras prepared with nonmyeloablative conditioning, we previously showed that recipient leukocyte infusions (RLIs) induce loss of donor chimerism and mediate antitumor responses against host-type tumors. We assessed the clinical relevance of our mouse model. METHODS: Mixed chimeric mice were generated by a nonmyeloablative protocol and some of them received host-derived tumor cells and/or RLIs or donor lymphocyte infusion (DLI). We examined chimerism, graft-versus-host disease (GVHD), and tumor survival. RESULTS: RLI is still effective when the leukocytes are obtained from tumor-bearing mice. Established mixed chimerism is required prior to the induced rejection to achieve maximum antitumor effects. The antitumor effects of RLI are not dependent on a specific donor strain or conditioning protocol. In contrast to DLI, RLI leads to donor cell rejection without the risk of GVHD. CONCLUSION: Together, these data reinforce the clinical potential of RLI therapy as a new HCT strategy that does not carry the risk of GVHD.     

Treatment of lymphoma relapses after allogeneic hematopoietic stem cell transplantation with intensive chemotherapy followed by infusion of hematopoietic stem cell from the original donor

Five lymphoma patients relapsed from allogeneic hematopoietic stem cell transplantation (HSCT). Three patients who received myeloablative conditioning had full donor chimerism at relapse, whereas two who received nonmyeloablative conditioning had partially or completely lost the graft. All received mini-BEAM [carmustine (BCNU), etoposide, cytarabine (AraC), melphalan], followed by infusion of HSC (four peripheral blood, one marrow) from the initial donor. Neutropenia and thrombocytopenia were brief, and full donor chimerism was established in all cases. There were four complete and one partial remissions. Graft-versus-host disease occurred in three cases, all with full donor chimerism at relapse. Two patients died subsequently of disease relapse or progression. Another two patients died from fungal infection, one of whom was still in remission at death. One patient had remained in remission 47 months after treatment. Mini-BEAM/HSC is an effective treatment for lymphoma relapses after allogeneic HSCT, but optimal strategies of remission consolidation and prevention of treatment-related complications are needed to improve outcome.     

A comparative study of reduced dose alemtuzumab in matched unrelated donor and related donor reduced intensity transplants

In vivo T cell depletion with 100 mg alemtuzumab prevents graft‐versus‐host disease (GVHD) in reduced intensity conditioned transplants but is associated with delayed immune reconstitution, a higher risk of infection and relapse. De‐escalation studies have shown that a reduced dose of 30 mg is as effective as 100 mg in preventing GVHD in matched related donor (MRD) transplants. Dose reduction in matched unrelated donor (MUD) transplants is feasible but the comparative efficacy of alemtuzumab in this setting is not known and opinions vary widely concerning the optimal level of GVHD prophylaxis that should be achieved. Through retrospective analysis we made an objective comparison of MUD transplants receiving an empirically reduced dose of 60 mg, with MRD transplants receiving a 30 mg dose. We observed proportionate levels of alemtuzumab according to dose but an inverse relationship with body surface area particularly in MRD transplants. MUD transplants experienced more acute and chronic GVHD, higher T cell chimerism, more sustained use of ciclosporin and less need for donor lymphocyte infusion than MRD transplants. Thus, doubling the dose of alemtuzumab to 60 mg did not provide equivalent prevention of GVHD after MUD transplant although there was no difference in non‐relapse mortality or survival compared with MRD transplants.     

Lack of utility of chimerism studies obtained 2-3 months after myeloablative hematopoietic cell transplantation for ALL

Lineage-specific chimerism studies are commonly obtained at several time points after nonmyeloablative hematopoietic cell transplantation to assess the tempo and degree of engraftment, and to monitor graft rejection. For patients who receive myeloablative transplants, the value of frequent chimerism analyses using sensitive molecular techniques is less certain. In this study, a retrospective analysis was performed to assess the transplant outcome of 89 adult patients with ALL who had chimerism studies of unfractionated BM cells or peripheral blood subsets performed approximately 80 days after transplantation. These patients received unmanipulated, myeloablative transplants using either HLA-identical or HLA-mismatched, related or unrelated donor stem cells. Incomplete donor engraftment was present only in the CD3(+) peripheral blood T cells in a small percentage of patients. There was no correlation of mixed chimerism with transplant outcome. Routine 'day 80' chimerism studies in this group of patients who receive intensive, myeloablative conditioning regimens are not recommended.Bone Marrow Transplantation (2008) 42, 271-274; doi:10.1038/bmt.2008.155; published online 26 May 2008.     

Acute polymyositis after donor lymphocyte infusion

Polymyositis usually occurred along with other manifestations of chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT) had been reported. However, polymyositis with a sole manifestation of acute GVHD following donor lymphocyte infusion (DLI) is rare. We reported a 45-yr-old man of acute lymphoid leukemia post-allogeneic HSCT 6 months developed acute polymyositis after DLI. He did not develop any symptoms, signs of acute or chronic GVHD following allogeneic HSCT, despite withdraw of immuosuppresive agents, cyclosporin A (CsA). As the DNA-STR of bone marrow analysis showed mixed chimerism, he received the DLI for remission on May 16, 2002. Acute polymyositis developed following DLI 22 d later. The clinical presentation of polymyositis is compatible with a manifestation of acute GVHD following DLI. It also responds to the treatment of steroid and CsA.     

Neonatal bone marrow transplantation of ADA-deficient SCID mice results in immunologic reconstitution despite low levels of engraftment and an absence of selective donor T lymphoid expansion

Adenosine deaminase (ADA)–deficient severe combined immune deficiency (SCID) may be treated by allogeneic hematopoietic stem cell transplantation without prior cytoreductive conditioning, although the mechanism of immune reconstitution is unclear. We studied this process in a murine gene knockout model of ADA-deficient SCID. Newborn ADA-deficient pups received transplants of intravenous infusion of normal congenic bone marrow, without prior cytoreductive conditioning, which resulted in long-term survival, multisystem correction, and nearly normal lymphocyte numbers and mitogenic proliferative responses. Only 1% to 3% of lymphocytes and myeloid cells were of donor origin without a selective expansion of donor-derived lymphocytes; immune reconstitution was by endogenous, host-derived ADA-deficient lymphocytes. Preconditioning of neonates with 100 to 400 cGy of total body irradiation before normal donor marrow transplant increased the levels of engrafted donor cells in a radiation dose–dependent manner, but the chimerism levels were similar for lymphoid and myeloid cells. The absence of selective reconstitution by donor T lymphocytes in the ADA-deficient mice indicates that restoration of immune function occurred by rescue of endogenous ADA-deficient lymphocytes through cross-correction from the engrafted ADA-replete donor cells. Thus, ADA-deficient SCID is unique in its responses to nonmyeloablative bone marrow transplantation, which has implications for clinical bone marrow transplantation or gene therapy.