Bone Marrow Transplantation (2008) 42, S47–S50; doi:10.1038/bmt.2008.283

The use of reduced-intensity stem cell transplantation in haemophagocytic lymphohistiocytosis and Langerhans cell histiocytosis

N Cooper1, K Rao1, N Goulden1, D Webb1, P Amrolia1 and P Veys1

1Department of Bone Marrow Transplantation, Great Ormond Street Hospital for Children NHS Trust, London, UK

Correspondence: Dr P Veys, Department of Bone Marrow Transplantation, Great Ormond Street Hospital for Children NHS Trust, Great Ormond Street, London WC1N 3JH, UK. E-mail:



Allogeneic stem cell transplant is curative for haemophagocytic lymphohistiocytosis (HLH) and refractory Langerhans cell histiocytosis (LCH). However, patients frequently have significant pre-transplant morbidity and there is high TRM. Because HLH is caused by immune dysregulation, we surmised that a reduced-intensity conditioned (RIC) regimen might be sufficient for cure, while decreasing the TRM. In 2006, we reported the outcome of 12 patients treated with RIC SCT from a matched family/unrelated or haploidentical donor. Here we discuss the update of these patients, including a total of 25 patients treated with RIC SCT for HLH and three for LCH. Twenty-one of the twenty-five patients with HLH (84%) are alive and well with remission at a median of 36 months from SCT. Mortality included pneumonitis (n=3) and hepatic rupture (n=1). All three patients treated with RIC SCT for LCH remain alive and in remission at a median of 5.1 years from SCT. Seven of twenty-four survivors (one with LCH) have mixed chimerism but remain disease-free. These data are supported by other groups including 100% survival in seven patients with HLH and 78% survival of nine patients with LCH. In summary, RIC compares favourably with conventional SCT with long-term disease control in surviving patients with both HLH and LCL, despite a significant incidence of mixed chimerism.


HLH, histiocytosis, LCH, SCT, reduced-intensity conditioning



Primary haemophagocytic lymphohistiocytosis (HLH) is a disease of childhood presenting with fever, hepatosplenomegaly and pancytopenia.1, 2 It is characterized by a selective deficiency of cellular cytotoxicity with hyperactivation of T cells and macrophages.3, 4, 5 A number of genetic abnormalities have been described,6, 7, 8, 9, 10, 11 which suggest that a deficiency of triggering T cell apoptosis may be responsible for the pathological features.

Patients with HLH may achieve remission with immunomodulation including epipodophyllin and steroids with or without CsA.10, 12 However, the only curative option is allo-SCT.13, 14 Patients often have significant pre-transplant morbidity and require intensive cardiorespiratory support pre-SCT. This toxicity results in a high TRM with conventional intensity conditioning, mostly from non-infectious pulmonary toxicity and veno-occlusive disease. In the HLH94 study, the TRM was 30%,15 with a 3-year overall survival of 71% following a matched related donor transplant, 70% for matched unrelated, 54% for mismatched unrelated donor and 50% for those with a haploidentical donor.

Langerhans cell histiocytosis (LCH) is a different disorder where CD1a+LCH cells are arrested in an immature, partially activated stage, also causing a cytokine storm type syndrome. There is a spectrum of symptoms with those at high risk (very young children with extensive disease and organ dysfunction) having a very poor prognosis. In particular, patients who do not respond within 6 weeks of conventional therapy or relapse early in the course of their disease have a poor prognosis with conventional chemotherapy. The DAH-HX studies describe a probability of survival at 5 years of only 0.11±0.10 for non-responders,16 and in LCH-I and LCH-II, 5-year survival was only 20–34% in patients who failed to respond after 2 cycles of chemotherapy.17, 18 SCT can provide a cure for these patients.19 However, patients typically have multi-organ involvement with high pre-transplant morbidity and consequently high TRM.

Following our experience, in children with primary immunodeficiencies, that reduced-intensity conditioning (RIC) may decrease the TRM from SCT,20 we hypothesized that SCT with RIC might be sufficient to restore normal immune regulation and hence cure HLH and LCH while decreasing the TRM. In 2006, we published data on 12 patients treated with an RIC SCT.21 We report here the update of this series to include a total of 25 patients. We also report three children with LCH whom we have treated with RIC SCT.



Patients HLH

Twenty-five consecutive patients with primary HLH at Great Ormond Street Hospital underwent SCT from an unrelated (fully matched unrelated donor (MUD), n=8; 1 antigen-mismatched unrelated donor, n=11) or phenotypically matched family (n=2) or haploidentical (n=4) donor using RIC between June 1999 and January 2008. Seven patients had underlying primary immunodeficiencies, one child had Down's syndrome and nine had mutations in the perforin gene. Genetic abnormalities and pre-transplant co-morbidities are shown in Table 1. Patients were prospectively enrolled, and there were no formal entry criteria. Patients were initially chosen on the clinician's judgment that TRM was likely to be unacceptably high with conventional conditioning because of significant coexisting morbidity. More recently, owing to our good overall survival, all patients regardless of comorbidities became eligible. All patients had previously received HLH 94 protocol and 22 were in CR at the time of transplant.

Preparative regimen, transplantation and supportive care HLH

Patients were conditioned with fludarabine 30mg/m2 × 5 (days −7 to −3) and melphalan 140mg/m2 (day −2) in the patients receiving matched family/unrelated donor transplants or 125mg/m2 (day −1) in the patients receiving haploidentical grafts. Patients receiving matched family/unrelated donor transplants received serotherapy with Campath-1H 0.2mg/kg × 5 (days −8 to −4) and those receiving haploidentical transplants received antithymocyte globulin 5mg/kg × 5 (days −5 to −1) together with busulphan 4mg/kg × 2 (days −9 to −8) for additional myelosuppression. One patient received a modified RIC-Haplo protocol with addition of thiotepa (10mg/kg) to fludarabine/melphalan and OKT3 instead of antithymocyte globulin (Bader P, personal communication). Two patients underwent minimal intensity conditioning. One who was ventilated at the time of transplant received fludarabine 30mg/m2 × 3 (days −4 to −2) and 2Gy TBI in a single fraction, and the other patient received fludarabine 120mg/m2, CY 30mg/m2, Campath IH and two anti-CD45 MoAbs. Grafts were T-replete marrow (matched family donor/MUD) or PBSCs (mismatched unrelated donor) and G-CSF mobilized CD34 selected or CD3/CD19 depleted PBSCs (CliniMACs) for the haploidentical donors. GVHD and antimicrobial prophylaxis were as described earlier.20

Analysis of chimerism

Engraftment was assessed on the peripheral blood using VNTR analysis with multiple informative alleles. Lineage specific chimerism analysis was performed after selection of CD3/CD15/CD56/CD19-positive cells using the MACs system (Miltenyi Biotec, GmbH, Bergisch Gladbach, Germany).



Toxicity and Survival HLH

Twenty-one of twenty-five (84%) children are alive and in CR at a median of 36 months from transplant (range 2–105 months) with Lansky scores of 90–100%. There were four TRMs from CMV pneumonitis (n=1), multifactorial pneumonitis following T cell sequestration and CMV disease on the background of previous pulmonary HLH (n=1), para-influenza pneumonitis (n=1) and hepatic rupture post-transjugular liver biopsy (n=1). No patients developed veno-occlusive disease. Nine patients had CMV reactivation and nine reactivated EBV.

Engraftment and chimerism

All patients engrafted at a median of 14 days to neutrophil engraftment and a median of 16 days to an unsupported platelet count >20 × 109/l. All patients had 100% donor cells at engraftment. Six of the twenty-one survivors subsequently developed mixed chimerism. Chimerism was stable after 6 months post-SCT. No patient rejected their grafts or relapsed. No patient has received lymphocyte infusions for management of mixed chimerism.

Immune reconstitution

Seventeen patients are alive with greater than 14 months follow-up. All of those assessed have achieved normal T cell levels and function, as assessed by PHA stimulation index, at a median of 7.5 months from SCT. One patient with X-linked lymphoproliferative syndrome had decreased natural killer T (CD3+CD56+) cells before transplant, which increased to normal levels post-transplant (2.9 × 105/l–2.08 × 106/l) and remains in remission. All nine patients with less than 14 months follow up (eight with <6 months follow-up) remain lymphopenic.

Further published studies of RIC SCT in patients with HLH are limited. An abstract presented at the Histiocyte Society Meeting 2007 (Vaughn et al.22) describes 100% survival in 10 children with HLH (7) or X-linked lymphoproliferative syndrome (3) treated with a Campath/fludarabine/melphalan RIC SCT. Six patients developed mixed chimerism, with four receiving repeated T cell infusions. All 10 are alive and well and remain in remission at a median of 10 months.


We have treated three patients with LCH with RIC SCT at Great Ormond Street Hospital between 2002 and 2008. Two had failed to respond to standard chemotherapy and one had an early relapse of LCH. Patients were aged 3, 18 and 24 months and received matched sibling donor-SCT (n=1) or MUD-SCT (n=2). All received Campath-H1 0.2mg/kg/day × 4, fludarabine 30mg/m2 × 5 and melphalan 140mg/m2 (day −2). All three remain alive and well 6 months, 5.1 and 6 years from transplant. One patient has mixed chimerism with 70% donor whole blood, >99% granulocytes, 60% mononuclear cells and 50% DCs and remains in remission. In a larger series, Steiner and co-workers described nine patients treated with RIC-SCT for refractory LCH. Their regimen included fludarabine in all patients, melphalan in eight patients, TLI in six patients, TBI in two patients, antithymocyte globulin in five patients and Campath 1H in four patients. Seven of nine patients are alive and in remission at a median of 390 days from SCT, including one with graft failure and autologous reconstitution.23



Our results with an RIC SCT in patients with HLH and LCH and significant pre-SCT morbidity are encouraging. Only one further patient has died from the 13 patients with HLH treated since our first publication in 2006.21 The overall survival data continue to compare favourably with historical data, particularly for patients receiving mismatched SCT (Table 2). In our group, 7 of 8 patients (87%) transplanted from a MUD and 9 of 11 (82%) transplanted from an HLA-mismatched donor survive in CR, compared with corresponding figures of 70 and 54% in the HLH 94 study.15 As reported earlier, viral reactivations remain frequent with the immunosuppressive RIC.20 However, only 2 of 25 patients died directly of infectious causes.

Six surviving HLH patients and one LCH patient remain in long-term remission despite being mixed chimeras. All had high-level donor T-cell engraftment. As discussed earlier by us, these data suggest that the presence of donor T-cells is sufficient to restore normal immunoregulation, prevent hypercytokinaemia and macrophage activation; and that myeloablation is not critical for cure of HLH or LCH, although the data for the latter disease are more limited. A multinational study is underway under the auspices of the Histiocyte Society to examine the role of RIC SCT in refractory LCH (Scott Baker, personal communication).

Given these results from our updated cohort and similar results from other centres, we would recommend RIC SCT in patients with HLH and refractory LCH particularly with organ dysfunction but also for standard risk patients. We have noted earlier a higher incidence of rejection in patients with immunodeficiency, transplanted from a matched sibling donor using the Campath/fludarabine/melphalan protocol, reflecting the reduced donor versus host alloreactivity. Given the risk of rejection (which may predispose to relapse24) in such patients, we would recommend conventional intensity conditioning in these patients at present, unless precluded by significant pre-SCT morbidity. In addition to the lower TRM, we predict that the incidence of end-organ damage, infertility and growth retardation may be lower than with conventional intensity conditioning, although demonstrating that this will require longer-term follow-up.


Conflict of interest

Nichola Cooper and Paul Veys have received grant funding that is not relevant to this paper. The remaining authors have declared no financial interests.



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