Improved outcome in haemophagocytic lymphohistiocytosis after bone marrow transplantation from related and unrelated donors: a single-centre experience of 12 patients

Second Allogeneic Hematopoietic Stem Cell Transplantation for Hemophagocytic Syndrome with Engraftment Failure

This study aims to assess the efficacy of second allogeneic hemopoietic stem cell transplantation (allo-HSCT) for treating hemophagocytic syndrome with first engraftment failure. Among a total of 35 patients who underwent allo-HSCT between June 2015 and July 2021 for HLH, 10 patients who underwent a second HSCT following graft rejection were retrospectively analyzed. Various factors, such as the treatment course and outcome, the remission status, donor selection, and the conditioning regimen of patients before second allo-HSCT, were scrutinized for transplant-related complications and transplant-related mortality, as well as transplant outcomes. All the subjects have achieved complete donor engraftment, in which the neutrophils and platelets engraftment occurred in a median time of 12 d (range 10–19 d) and 24 d (range 11–97 d), respectively. Among the selected subjects, 20% of patients are diseased due to transplant-related thrombotic microangiopathy. Further, 90% of patients are diagnosed with aGVHD, in which 3 of them with grade I aGVHD, one patient with grade II aGVHD, two patients with grade III GVHD, and three patients with localized chronic GVHD. Moreover, 70% of patients showed signs of combined viral infections. Despite the complex symptoms, the overall survival rate is around 80%, with transplant-related mortality and the incidence of post-transplant GVHD of 20% and 60%, respectively. Together, our findings indicated that the second allo-HSCT showed great potential in treating hemophagocytic syndrome with engraftment failure.

Hemophagocytic Lymphohistiocytosis Complicated by Acute Respiratory Distress Syndrome and Multiorgan Failure

Hemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening condition that is characterized by an overactive response of the immune system with excessive production of proinflammatory cytokines. Initial presentation of this condition often mimics and overlaps with many diseases including infections, sepsis, and multiorgan failure syndrome, which makes diagnosis the diagnosis of HLH challenging. Herein is described a case of a patient who developed acute respiratory distress syndrome and multiple organ failure related to HLH in a setting of probable viral pneumonia. The diagnosis was established based on laboratory and bone marrow biopsy findings. This patient was treated with the standard chemotherapy regimen of intravenous dexamethasone, etoposide in addition to intrathecal methotrexate for central nervous system involvement.

Lentiviral Gene Therapy for Familial Hemophagocytic Lymphohistiocytosis Type 3, Caused by UNC13D Genetic Defects

Familial hemophagocytic lymphohistiocytosis type 3 (FHL3) is a rare disease caused by mutations to the UNC13D gene and the subsequent absence or decreased activity of the Munc13-4 protein. Munc13-4 is essential for the exocytosis of perforin and granzyme containing granules from cytotoxic cells. Without it, these cells are able to recognize an immunological insult but are unable to execute their cytotoxic functions. The result is a hyperinflammatory state that, if left untreated, is fatal. At present, the only curative treatment is hematopoietic stem cell transplantation (HSCT), but eligibility and response to this treatment are largely dependent on the ability to control inflammation before HSCT. In this study, we describe an optimized lentiviral vector that can restore Munc13-4 expression and degranulation capacity in both transduced FHL3 patient T cells and transduced hematopoietic stem cells from the FHL3 (Jinx) disease model.

Stem cell transplantation for children with hemophagocytic lymphohistiocytosis: results from the HLH-2004 study

We report the largest prospective study thus far on hematopoietic stem cell transplantation (HSCT) in hemophagocytic lymphohistiocytosis (HLH), a life-threatening hyperinflammatory syndrome comprising familial/genetic HLH (FHL) and secondary HLH. Although all patients with HLH typically need intensive anti-inflammatory therapy, patients with FHL also need HSCT to be cured. In the international HLH-2004 study, 187 children aged <18 years fulfilling the study inclusion criteria (5 of 8 diagnostic criteria, affected sibling, or molecular diagnosis in FHL-causative genes) underwent 209 transplants (2004-2012), defined as indicated in patients with familial/genetic, relapsing, or severe/persistent disease. Five-year overall survival (OS) post-HSCT was 66% (95% confidence interval [CI], 59-72); event-free survival (EFS) was 60% (95% CI, 52-67). Five-year OS was 81% (95% CI, 65-90) for children with a complete response and 59% (95% CI, 48-69) for those with a partial response (hazard ratio [HR], 2.12; 95% CI, 1.06-4.27; P = .035). For children with verified FHL (family history/genetically verified, n = 134), 5-year OS was 71% (95% CI, 62-78) and EFS was 62% (95% CI, 54-70); 5-year OS for children without verified FHL (n = 53) was significantly lower (52%; 95% CI, 38-65) (P = .040; HR, 1.69; 95% CI, 1.03-2.77); they were also significantly older. Notably, 20 (38%) of 53 patients without verified FHL had natural killer cell activity reported as normal at diagnosis, after 2 months, or at HSCT, suggestive of secondary HLH; and in addition 14 (26%) of these 53 children had no evidence of biallelic mutations despite having 3 or 4 FHL genes analyzed (natural killer cell activity not analyzed after 2 months or at HSCT). We conclude that post-HSCT survival in FHL remains suboptimal, and that the FHL diagnosis should be carefully investigated before HSCT. Pretransplant complete remission is beneficial but not mandatory to achieve post-HSCT survival. This trial was registered at www.clinicaltrials.gov as #NCT00426101.

Targeted busulfan-based reduced-intensity conditioning and HLA-matched HSCT cure hemophagocytic lymphohistiocytosis

Reduced-intensity/reduced-toxicity conditioning and allogeneic T-cell replete hematopoietic stem cell transplantation are curative in patients with hemophagocytic lymphohistiocytosis (HLH). Unstable donor chimerism (DC) and relapses are clinical challenges . We examined the effect of a reduced-intensity conditioning regimen based on targeted busulfan to enhance myeloid DC in HLH. The European Society for Bone and Marrow Transplantation-approved reduced-intensity conditioning protocol comprised targeted submyeloablative IV busulfan, IV fludarabine, and serotherapy comprising IV alemtuzumab (0.5-0.8 mg/kg) for unrelated-donor and IV rabbit anti-T-cell globulin for related-donor transplants. We assessed toxicity, engraftment, graft-versus-host disease (GHVD), DC in blood cell subtypes, and overall survival/event-free survival. Twenty-five patients from 7 centers were treated (median age, 0.68 year). The median total dose and cumulative area under the curve of busulfan was 13.1 mg/kg (6.4-26.4) and 63.1 mg/L × h (48-77), respectively. Bone marrow, peripheral blood stem cell, or cord blood transplants from HLA-matched related (n = 7) or unrelated (n = 18) donors were administered. Donor cells engrafted in all patients (median: neutrophils d+20/platelets d+28). At last follow-up (median, 36 months; range, 8-111 months), the median DC of CD15+ neutrophils, CD3+ T cells, and CD16+56+ natural killer cells was 99.5% (10-100), 97% (30-100), and 97.5% (30-100), respectively. Eight patients (32%) developed sinusoidal obstruction syndrome, resolving after defibrotide treatment. The 3-year overall survival and event-free survival rates were both 100%. None of the patients developed acute grade III to IV GHVD. Limited chronic GVHD was encountered in 4%. This regimen achieves excellent results with stable DC in patients with HLH.

Impact of graft-versus-host disease on the clinical outcome of allogeneic hematopoietic stem cell transplantation for non-malignant diseases

The impact of acute and chronic graft-versus-host disease (GVHD) on clinical outcomes was retrospectively analyzed in 960 patients with non-malignant diseases (NMD) who underwent a first allogeneic hematopoietic stem cell transplantation (HSCT). Grade III-IV acute GVHD (but not grade I-II) was significantly associated with a lower rate of overall survival (OS), and higher non-relapse mortality (NRM) than that seen in patients without acute GVHD. Extensive (but not limited) GVHD was significantly associated with a lower OS rate and higher NRM than that seen in patients without chronic GVHD. Any grade of acute (but not chronic) GVHD was significantly associated with a lower incidence of relapse and a lower proportion of patients requiring a second HSCT or donor lymphocyte infusion for graft failure or mixed chimerism, but its impact on OS was almost negligible. Acute GVHD was significantly associated with lower OS rates in all disease groups, whereas chronic GVHD was significantly associated with lower OS rates in the primary immunodeficiency and histiocytosis groups. In conclusion, acute and chronic GVHD, even if mild, was associated with reduced OS in patients receiving HSCT for NMD and effective strategies should, therefore, be implemented to minimize GVHD.

Early onset lysosomal acid lipase deficiency presenting as secondary hemophagocytic lymphohistiocytosis: Two infants treated with sebelipase alfa

Two unrelated infants were diagnosed with and initially treated for hemophagocytic lymphohistiocytosis (HLH), but progressed to cholestasis and liver failure. Early onset lysosomal acid lipase deficiency (EO-LAL-D) was suspected due to lymphocytes with cytoplasmic vacuolation and/or adrenal calcifications and confirmed by enzymatic and genetic analysis. Enzyme replacement therapy with sebelipase alfa was implemented, but both children died, despite initial improvement. Since this inborn error of metabolism progresses rapidly in infants, early diagnosis is crucial, and appropriate treatment should be started as soon as possible. The authors suggest that the diagnosis of EO-LAL-D should be considered in infants with symptoms of HLH.

Treatment dilemmas in asymptomatic children with primary hemophagocytic lymphohistiocytosis

Asymptomatic carriers (ACs) of pathogenic biallelic mutations in causative genes for primary hemophagocytic lymphohistiocytosis (HLH) are at high risk of developing life-threatening HLH, which requires allogeneic hematopoietic stem cell transplantation (HSCT) to be cured. There are no guidelines on the management of these asymptomatic patients. We analyzed the outcomes of pairs of index cases (ICs) and subsequently diagnosed asymptomatic family members carrying the same genetic defect. We collected data from 22 HSCT centers worldwide. Sixty-four children were evaluable. ICs presented with HLH at a median age of 16 months. Seven of 32 ICs died during first-line therapy, and 2 are alive after chemotherapy only. In all, 23/32 underwent HSCT, and 16 of them are alive. At a median follow-up of 36 months from diagnosis, 18/32 ICs are alive. Median age of ACs at diagnosis was 5 months. Ten of 32 ACs activated HLH while being observed, and all underwent HSCT: 6/10 are alive and in complete remission (CR). 22/32 ACs remained asymptomatic, and 6/22 have received no treatment and are in CR at a median follow-up of 39 months. Sixteen of 22 underwent preemptive HSCT: 15/16 are alive and in CR. Eight-year probability of overall survival (pOS) in ACs who did not have activated HLH was significantly higher than that in ICs (95% vs 45%; P = .02), and pOS in ACs receiving HSCT before disease activation was significantly higher than in ACs receiving HSCT after HLH activation (93% vs 64%; P = .03). Preemptive HSCT in ACs proved to be safe and should be considered.

Macrophage Activation Syndrome

Hemophagocytic lymphohistiocytosis (HLH), or termed macrophage activation syndrome (MAS) when associated with rheumatic disorders, is a frequently fatal complication of infections, rheumatic disorders, and hematopoietic malignancies. Clinically, HLH/MAS is a life-threatening condition that is usually diagnosed among febrile hospitalized patients (children and adults) who commonly present with unremitting fever and a shock-like multiorgan dysfunction scenario. Laboratory studies reveal pancytopenia, elevated liver enzymes, elevated markers of inflammation (ESR, CRP), hyperferritinemia, and features of coagulopathy. In about 60% of cases, excess hemophagocytosis (macrophages/histiocytes engulfing other hematopoietic cell types) is noted on biopsy specimens from the bone marrow, liver, lymph nodes, and other organs. HLH/MAS has been hypothesized to occur when a threshold level of inflammation has been achieved, and genetic and environmental risk factors are believed to contribute to the hyperinflammatory state. A broad variety of infections, from viruses to fungi to bacteria, have been identified as triggers of HLH/MAS, either in isolation or in addition to an underlying inflammatory disease state. Certain infections, particularly by members of the herpesvirus family, are the most notorious triggers of HLH/MAS. Treatment for infection-triggered MAS requires therapy for both the underlying infection and dampening of the hyperactive immune response.

Confirmed efficacy of etoposide and dexamethasone in HLH treatment: long-term results of the cooperative HLH-2004 study

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome comprising familial/genetic HLH (FHL) and secondary HLH. In the HLH-94 study, with an estimated 5-year probability of survival (pSu) of 54% (95% confidence interval, 48%-60%), systemic therapy included etoposide, dexamethasone, and, from week 9, cyclosporine A (CSA). Hematopoietic stem cell transplantation (HSCT) was indicated in patients with familial/genetic, relapsing, or severe/persistent disease. In HLH-2004, CSA was instead administered upfront, aiming to reduce pre-HSCT mortality and morbidity. From 2004 to 2011, 369 children aged <18 years fulfilled HLH-2004 inclusion criteria (5 of 8 diagnostic criteria, affected siblings, and/or molecular diagnosis in FHL-causative genes). At median follow-up of 5.2 years, 230 of 369 patients (62%) were alive (5-year pSu, 61%; 56%-67%). Five-year pSu in children with (n = 168) and without (n = 201) family history/genetically verified FHL was 59% (52%-67%) and 64% (57%-71%), respectively (familial occurrence [n = 47], 58% [45%-75%]). Comparing with historical data (HLH-94), using HLH-94 inclusion criteria, pre-HSCT mortality was nonsignificantly reduced from 27% to 19% (P = .064 adjusted for age and sex). Time from start of therapy to HSCT was shorter compared with HLH-94 (P =020 adjusted for age and sex) and reported neurological alterations at HSCT were 22% in HLH-94 and 17% in HLH-2004 (using HLH-94 inclusion criteria). Five-year pSu post-HSCT overall was 66% (verified FHL, 70% [63%-78%]). Additional analyses provided specific suggestions on potential pre-HSCT treatment improvements. HLH-2004 confirms that a majority of patients may be rescued by the etoposide/dexamethasone combination but intensification with CSA upfront, adding corticosteroids to intrathecal therapy, and reduced time to HSCT did not improve outcome significantly.

Hematopoietic cell transplantation for hemophagocytic lymphohistiocytosis: recent advances and controversies

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory clinical syndrome of uncontrolled immune response which results in hypercytokinemia due to underlying primary or secondary immune defect. A number of genetic defects in transport, processing and function of cytotoxic granules which result in defective granule exocytosis and cytotoxicity of cytotoxic T lymphocytes (CTL) and natural killer (NK) cells have been well identified at the cellular and molecular level. Important advances have been made during the last 20 years in the diagnosis and treatment of HLH. The Histiocyte Society has proposed diagnostic guideline using both clinical and laboratory findings in HLH-2004 protocol, and this has been modified partly in 2009. HLH used to be a fatal disease, but the survival of HLH patients has improved to more than 60% with the use of chemoimmunotherapy combined with hematopoietic cell transplantation (HCT) over the past 2 decades. However, HCT is still the only curative option of treatment for primary HLH and refractory/relapsed HLH after proper chemoimmunotherapy. The outcome of HCT for HLH patients was also improved steadily during last decades, but HCT for HLH still carries significant mortality and morbidity. Moreover, there remain ongoing controversies in various aspects of HCT including indication of HCT, donor selection, timing of HCT, conditioning regimen, and mixed chimerism after HCT. This review summarized the important practical issues which were proven by previous studies on HCT for HLH, and tried to delineate the controversies among them.

Hemophagocytic syndrome in children and adults

Hemophagocytic syndrome, also known as hemophagocytic lymphohistiocytosis (HLH), is a heterogenic syndrome, which leads to an acute, life-threatening inflammatory reaction. HLH occurs both in children and adults, and can be triggered by various inherited as well as acquired factors. Depending on the etiology, HLH can be divided into genetic (i.e., primary) and acquired (i.e., secondary) forms. Among genetic HLH forms, one can distinguish between familial HLH and other genetically conditioned forms of HLH. Acquired HLH can be typically triggered by infections, autoimmune diseases, and malignancies. The most common symptoms of HLH are unremitting fever, splenomegaly, and peripheral blood cytopenia. Some severely ill patients present with central nervous system involvement. Laboratory tests reveal hyperferritinemia (often >10,000 μg/L), increased serum concentration of soluble receptor α for interleukin-2 (>2,400 U/L), hypertriglyceridemia, hypofibrinogenemia, coagulopathy, hyponatremia, hypoproteinemia, and elevated liver transaminases and bilirubin. Prognosis in HLH is very serious. Genetic HLH is always lethal if adequate therapy is not administered. Similarly, severe acquired cases often lead to death without appropriate treatment. Since HLH can be encountered by various specialists in the medical field, basic knowledge of this entity such as diagnostic criteria and treatment should be familiar to all physicians.

Hemophagocytic lymphohistiocytosis: review of etiologies and management

Hemophagocytic lymphohistiocytosis (HLH) covers a wide array of related life-threatening conditions featuring ineffective immunity characterized by an uncontrolled hyperinflammatory response. HLH is often triggered by infection. Familial forms result from genetic defects in natural killer cells and cytotoxic T-cells, typically affecting perforin and intracellular vesicles. HLH is likely under-recognized, which contributes to its high morbidity and mortality. Early recognition is crucial for any reasonable attempt at curative therapy to be made. Current treatment regimens include immunosuppression, immune modulation, chemotherapy, and biological response modification, followed by hematopoietic stem-cell transplant (bone marrow transplant). A number of recent studies have contributed to the understanding of HLH pathophysiology, leading to alternate treatment options; however, much work remains to raise awareness and improve the high morbidity and mortality of these complex conditions.

Risk for complications in patients with hemophagocytic lymphohistiocytosis who undergo hematopoietic stem cell transplantation: myeloablative versus reduced-intensity conditioning regimens

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative option for patients with primary hemophagocytic lymphohistiocytosis (HLH) and for patients with secondary HLH who fail to respond to therapy. Advances in HSCT and supportive care measures have resulted in improved patient outcomes and decreased treatment-related mortality. Despite the overall improvement in outcome, HLH patients who undergo HSCT using myeloablative conditioning regimens are still at significant risk for complications. The HLH-94 study conducted by the Histiocyte Society reported a 30% TRM with increased pulmonary and hepatic complications. Recently, the use of reduced-intensity conditioning (RIC) regimens has shown favorable outcomes when compared to conventional HSCT and lower rate of acute complications. In this review we compare the potential complications of myeloablative and RIC regimens for HSCT in HLH patients.

Increased complications and morbidity in children with hemophagocytic lymphohistiocytosis undergoing hematopoietic stem cell transplantation

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is the only curative option for patients with primary hemophagocytic lymphohistiocytosis (HLH) and for patients with secondary HLH who fail to respond to therapy.

METHODS

Retrospective study of HSCT for HLH with focus on complications and outcome.

RESULTS

Eighteen children (10 males), with a median age of 1.2 yr (5 months-16 yr), received HSCT for HLH. Fourteen children had primary HLH. Four children underwent transplant while not in remission. Sixteen received myeloablative and two received reduced intensity conditioning regimen. A high incidence of complications was found: 13 (72%) children had 22 episodes of culture-proven infections; seven (38%) had hepatic veno-occlusive disease; nine (50%) developed respiratory complications; and nine (50%) required intensive care unit admission. Eight children had acute graft-versus-host disease (GVHD), and three developed chronic GVHD. Three patients died from multi-organ failure before day +100, and another patient died from pulmonary hemorrhage after day 100. Three patients failed to engraft (two developed recurrent HLH and died from complications after a second HSCT). Three of four children not in remission at the time of transplantation died. Actuarial survival at three yr was 61%.

CONCLUSION

HSCT for HLH carries significant risks with high infection, organ dysfunction, and ICU admissions rates.

Reduced-intensity conditioning haematopoietic cell transplantation for haemophagocytic lymphohistiocytosis: an important step forward

Haemophagocytic lymphohistiocytosis (HLH) is a life-threatening immunodeficiency characterized by severe systemic hyper-inflammatory responses to infectious or other triggers of the immune system. In many patients, the underlying cause of HLH is a genetic defect leading to defective CD8(+) T cell and natural killer cell granule-mediated cytotoxicity. The treatment of HLH consists principally of immune suppression followed by allogeneic haematopoietic cell transplantation (HCT) to cure the underlying defect and prevent relapse of HLH. Initial treatment regimens consist of steroids coupled with either etoposide or antithymocyte globulin, ± ciclosporin. Complete responses are observed in only 50-75% of patients and even after a complete response, relapse and death still occur. The only definitive, long-term cure for patients with genetic forms of HLH is allogeneic HCT. Unfortunately, allogeneic HCT for patients with HLH is often complicated by critical illness, extensive organ involvement, active infections, or refractory HLH. For these reasons, patients are unusually prone to developing transplant-related toxicities and complications. In recent years, great strides have been made with regard to the care and transplantation of patients with HLH. Here we review the current state of the treatment of patients with HLH with allogeneic HCT, highlighting the important steps forward that have been made with reduced-intensity conditioning.

Successful treatment of recurrent malignancy-associated hemophagocytic lymphohistiocytosis with a modified HLH-94 immunochemotherapy and allogeneic stem cell transplantation

Acquired hemophagocytic lymphohistiocytosis (HLH) triggered by a known or still to be recognized malignancy is a life-threatening hyperinflammatory syndrome due to massive cytokine release from activated lymphocytes and macrophages. Malignancy-associated HLH (M-HLH) often impedes adequate treatment of malignancy and has the worst outcome compared with any other form of HLH. The incidence of M-HLH is unknown, and there are no published treatment recommendations addressed to this HLH form. Here, we report the case of a young woman with recurrent ALK1-positive anaplastic large T-cell lymphoma and M-HLH successfully treated with a modified HLH-94 protocol, allogeneic stem cell transplantation (alloSCT) and donor lymphocyte infusion (DLI). More than 3 years after DLI, the patient is alive, in complete remission from her malignancy and HLH-free, although suffering from extensive chronic graft-versus-host disease. AlloSCT and, if needed, DLI performed to consolidate remission of malignancy and HLH may have a curative impact on both entities. We propose that when discussing possible treatment options for patients with M-HLH, alloSCT should be considered in eligible individuals.

The outcome of hematopoietic stem cell transplantation in Korean children with hemophagocytic lymphohistiocytosis

Chemoimmunotherapy-based treatments have improved the survival of patients with HLH, but outcomes of the patients are still unsatisfactory. We report here the outcome of Korean children with HLH who underwent HSCT, which was analyzed from the data of a nation-wide HLH registry. Retrospective nation-wide data recruitment for the pediatric HLH patients diagnosed between 1996 and 2008 was carried out by the Histiocytosis Working Party of the Korean Society of Hematology. Nineteen patients who received HSCT among the total of 148 enrolled children with HLH were analyzed for the transplant-related variables and events. The probability of five-yr survival after HSCT was 73.3% with a median follow-up of 57. Two months compared to 54.3% for the patients who were treated with chemoimmunotherapy only (p = 0.05). The reasons for HSCT were active disease after eight wk of initial treatment (n = 9), relapsed disease (n = 5), and FHL (n = 5). Fourteen patients are currently alive without disease after HSCT, four patients died of treatment-related events (infection in two and graft failure in two) at early post-transplant period, and one patient died of relapse at one yr post transplantation. The survival of patients who were transplanted because of active disease after eight wk of initial treatment was worse compared to those patients who had inactive state at that time (60.6% vs. 100%, respectively, p = 0.06). Of the four patients who received transplants using cord blood, three died of graft failure (n = 2) and relapse (n = 1). The five-yr probability of survival after HSCT according to the donor type was 85.7% for the MRDs (n = 6), 87.5% for the MUDs (n = 8), and 40% for the MMUDs (n = 5) (p = 0.03). Other variables such as age, CNS involvement at the time of diagnosis, the etiology of HLH (familial or secondary), and the conditioning regimens had no influence on the five-yr OS of the HLH patients who underwent HSCT. HSCT improved the survival of the patients who had familial, relapsed, or severe and persistent SHLH in the Korean nation-wide HLH registry. Although numbers were small, these results are similar to other reports in the literature. The disease state after initial treatment, the stem cell source of the transplant, and the donor type were the important prognostic factors that affected the OS of the HLH patients who underwent HSCT.

STXBP2 mutations in children with familial haemophagocytic lymphohistiocytosis type 5

BACKGROUND

Familial haemophagocytic lymphohistiocytosis (FHL) is a rare immune deficiency with uncontrolled inflammation; the clinical course usually starts within the first years of life, and is usually fatal unless promptly treated and then cured with haematopoietic stem cell transplant. FHL is caused by genetic mutations resulting in defective cell cytotoxicity; three disease related genes have been identified to date: perforin, Munc13-4 and syntaxin-11. A fourth gene, STXBP2, has been identified very recently as responsible for a defect in Munc18-2 in FHL-5.

AIMS

To describe the result of the screening of families with HLH and previously unassigned genetic defects.

METHODS

Patients with HLH diagnosed according to current diagnostic criteria, and who lacked mutations in the PRF1, Munc13-4, and STX11 genes were sequenced for mutations in STXBP2. Functional study was performed when material was available.

RESULTS

Among the 28 families investigated, 4 (14%) with biallelic STXBP2 mutations were identified. They originated from Italy, England, Kuwait and Pakistan. The p.Pro477Leu resulting from c.1430C>T, and p.Arg405Gln resulting from the single c.1214G>A nucleotide change are known, while we contribute two novel mutations: p.Glu132Ala resulting from c.395A>C, and p.Gly541Ser, resulting from c.1621G>A. The detrimental effect of the p.Gly541Ser mutation was documented biochemically and functionally in NK and CD8 cells. Additional polymorphisms are also described.

CONCLUSION

These data expand current knowledge on the genetic heterogeneity of FHL and suggest that patients with FHL5 may have different results in degranulation assays under different conditions.

Hematopoietic stem cell transplantation for familial hemophagocytic lymphohistiocytosis and Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis in Japan

BACKGROUND

Post-transplant outcomes of hemophagocytic lymphohistiocytosis (HLH) patients were analyzed in Japan where Epstein-Barr virus (EBV)-associated severe forms are problematic.

METHODS

Fifty-seven patients (43 familial HLH [12 FHL2, 11 FHL3, 20 undefined], 14 EBV-HLH) who underwent stem cell transplantation (SCT) between 1995 and 2005 were enrolled based on the nationwide registration.

RESULTS

Fifty-seven patients underwent 61 SCTs, including 4 consecutive SCTs. SCTs were employed using allogeneic donors in 93% of cases (allo 53, twin 1, auto 3). Unrelated donor cord blood transplantation (UCBT) was employed in half of cases (21 FHL, 7 EBV-HLH). Reduced intensity conditioning was used in 26% of cases. The 10-year overall survival rates (median +/- SE%) were 65.0 +/- 7.9% in FHL and 85.7 +/- 9.4% in EBV-HLH patients, respectively. The survival of UCBT recipients was >65% in both FHL and EBV-HLH patients. Three out of four patients were alive with successful engraftment after second UCBT. FHL patients showed a poorer outcome due to early treatment-related deaths (<100 days, seven patients) and a higher incidence of sequelae than EBV-HLH patients (P = 0.02). The risk of death for FHL patients having received an unrelated donor bone marrow transplant was marginally higher than that for a related donor SCT (P = 0.05) and that for UCBT (P = 0.07).

CONCLUSIONS

EBV-HLH patients had a better prognosis after SCT than FHL patients. FHL patients showed either an equal or better outcome even after UCBT compared with the recent reports. UCB might therefore be acceptable as an alternate SCT source for HLH patients, although the optimal conditioning remains to be determined.

UNC13D is the predominant causative gene with recurrent splicing mutations in Korean patients with familial hemophagocytic lymphohistiocytosis

BACKGROUND

Familial hemophagocytic lymphohistiocytosis is a fatal disease characterized by immune dysregulation from defective function of cytotoxic lymphocytes. Three causative genes have been identified for this autosomal recessive disorder (PRF1, UNC13D, and STX11). We investigated the molecular genetics of familial hemophagocytic lymphohistiocytosis in Korea.

DESIGN AND METHODS

Pediatric patients who fulfilled the HLH-2004 criteria were recruited from the Korean Registry for Histiocytosis. Molecular genetic studies were performed on the patients' DNA samples by direct sequencing of all coding exons and flanking sequences of PRF1, UNC13D, and STX11.

RESULTS

Forty patients were studied and familial hemophagocytic lymphohistiocytosis mutations were identified in nine; eight patients had UNC13D mutations (89%) and one had a mutation in PRF1. No patient had a STX11 mutation. Notably, four patients had only one UNC13D mutant allele, suggesting that the other mutation was missed by conventional direct sequencing. All UNC13D mutations were deleterious in nature. One known splicing mutation, c.754-1G>C, was recurrent, accounting for 58% of all the mutant alleles (7/12). Five UNC13D mutations were novel (p.Gln98X, p.Glu565SerfsX7, c.1993-2A>G, c.2367+1G>A, and c.2954+5G>A). The one patient with PRF1 mutation was homozygous for a frameshift mutation (p.Leu364GlufsX93), which was previously reported to be the most frequent PRF1 mutation in Japan.

CONCLUSIONS

This is the first investigation on the molecular genetics of familial hemophagocytic lymphohistiocytosis in Korea. The data showed that UNC13D is the predominant causative gene in the Korean population. The identification of mutations missed by conventional sequencing would better delineate the mutation spectrum and help to establish the optimal molecular diagnostic strategy for familial hemophagocytic lymphohistiocytosis in Korea, which might need an RNA-based screening strategy.

Patients with early relapse of primary hemophagocytic syndromes or with persistent CNS involvement may benefit from immediate hematopoietic stem cell transplantation

Primary hemophagocytic syndromes represent a group of rare immunodeficiencies, which are characterized by development of life-threatening systemic inflammatory manifestations, so-called accelerated phases. Immunosuppressive therapies are only temporarily effective to control this complication and the prognosis is dismal unless treated by hematopoietic SCT (HSCT). At present, optimal modalities of this potentially curative approach remain incompletely defined. In this study, we analyzed our experience in 18 patients with primary hemophagocytic syndromes treated since 1984 in our center by HSCT. Ten of these patients had previously developed accelerated phases and were in remission at the time of HSCT, whereas five patients had findings of active disease, with two cases in early phases of recurrences of less than 2 weeks duration and three cases with persistent central nervous system disease, whereas three patients had never experienced accelerated phases. In the group with active disease, four of five patients are long-term survivors and are well, whereas one patient died of CMV pneumonia. This outcome compares favorably with results in patients transplanted in remission, where 6 of 10 are long-term survivors. Our findings indicate that HSCT can have a favorable prognosis even in patients with active disease of primary hemophagocytic syndrome.

Pre- and post-natal treatment of hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare autosomal recessive disorder of infancy and childhood that is invariably fatal if not treated. We report on the first patient to receive post-natal HSCT for HLH after receiving in utero chemotherapy for disease stabilization.

Hemophagocytic lymphohistiocytosis and other hemophagocytic disorders

Hemophagocytic disorders result when critical regulatory pathways responsible for the natural termination of immune/inflammatory responses are disrupted or overwhelmed. Hemophagocytic disorders reflect pathologic defects that alter the normal crosstalk between innate and adaptive immune responses, and compromise homeostatic removal of cells that are superfluous or dangerous to the organism. Although hemophagocytic disorders are considered rare, increased awareness of these conditions has led to more frequent diagnoses, more rapid initiation of life-saving treatments, and new insights into the molecules and pathways involved in natural immune down-regulation. Furthermore, improved understanding of the immunologic abnormalities revealed by hemophagocytic disorders informs potential new treatments for life-threatening multisystem organ dysfunction related to sepsis in the intensive care unit setting and severe cases.

[Viral form of hemophagocytic syndrome with erythrodermal clinical picture--case report]

INTRODUCTION

Hemophagocytic syndrome is patophysiological entity with proliferation and over-activation of macrophages, with hemophagocytosis and production of proinflammatory cytokines. It arises as hereditary forms, or acquired, during viral, autoimmune or malignant diseases, and is usually a disorder with fulminant course and high incidence of lethal outcome. The precise mechanism is not resolved; it is a consequence of cytokine storm generated by over-activated T cells and macrophages, due to defects in T cellular cytototoxic function and inadequate down-regulation of immune response.

CASE REPORT

A male patient, 26 years old, previously healthy, is presented. Generalized exfoliative dermatitis and lymphadenomegalia had lasted for half a year before admission to the hospital. Hemophagocytosis in lymph gland histology was diagnostic, with T cellular immunohistochemical profile CD3+, CD5-, CD8/-, CD43+/-, CD45RO+, bcl-2+, and numerous CD68+ histiocytes. Apart from elevated titer of Adenovirus serology, other laboratory findings and bone marrow histology were within normal limits. Two weeks of oral antibiotic and topical skin corticosteroid therapy were followed by a rapid improvement of clinical features. Residual skin lesions, linear petechia and flares of pale pink erythema used to recur for the next half a year. During the follow up, two years later there was no lymph gland enlargement, skin rash, or other signs.

DISCUSSION

The diagnosis of virus-associated hemophagocytic syndrome with mild clinical course and seemingly spontaneous improvement was established, although it did not fulfill all proposed diagnostic criteria. It is possible that it increased the clinical awareness for these mild forms in immune-competent patients could account for the improved recognition of atypical cases with favorable outcome.

Fatal sibling cases of familial hemophagocytic lymphohistiocytosis (FHL) with MUNC13-4 mutations: case reports

The authors report here sibling cases of familial hemophagocytic lymphohistiocytosis (FHL) type 3 that took fatal courses despite intensive treatment. The older brother achieved remission by immunochemotherapy, but a central nervous system lesion occurred before the introduction of allogeneic hematopoietic stem cell transplantation (allo-HSCT). The patient died on day +1 of allo-HSCT due to progression of the disease. The younger brother developed symptoms of hemophagocytic lymphohistiocytosis mimicking neonatal hemochromatosis at birth. He died without a chance to receive allo-HSCT. Both siblings showed low natural killer cell (NK) activity and the compound heterozygous Munc13-4 gene mutations 1596+1 and 1723insA were identified postmortem in the younger brother. With recent progress in the molecular diagnosis of FHL, prompt and most appropriate therapeutic measures should be introduced to improve the prognosis of FHL patients.

Hemophagocytic lymphohistiocytosis and related disorders

PURPOSE OF REVIEW

The rate of diagnosis of hemophagocytic lymphohistiocytosis, a genetically heterogeneous and, frequently, rapidly fatal autosomal recessive disorder of immune regulation, is increasing worldwide. Awareness has grown through the Histiocyte Society and the publication of newly-recognized genetic causes. I summarize current knowledge regarding the pathophysiology, diagnosis and treatment of hemophagocytic lymphohistiocytosis.

RECENT FINDINGS

Genetic defects leading to life-threatening hemophagocytic syndromes have recently been described. Two autosomal recessive gene defects underlie 40-50% of primary (familial) cases worldwide: perforin, the major immune cytotoxic protein, and MUNC 13-4, a protein involved in exocytosis of perforin-bearing cytotoxic granules during apoptosis. Related autosomal recessive defects of secretory cytotoxic lysosomes - LYST 1 (Chediak-Higashi syndrome), Rab27A (Griscelli syndrome), and X-linked lymphoproliferative disorder - also carry a very high risk of fatal hemophagocytic lymphohistiocytosis. Concurrently, treatment protocols involving multiagent immunomodulatory therapy followed by allogeneic hematopoeitic cell transplantation have been tested. With immunomodulatory treatment, 75% of children with hemophagocytic lymphohistiocytosis are symptomatically improved after 2 months of therapy. Disease-free survival after allogeneic hematopoeitic cell transplantation currently ranges from 50 to 70%.

SUMMARY

Bench and clinical research have advanced understanding of the pathophysiology of hemophagocytic lymphohistiocytosis and related disorders, and significantly improved clinical outcomes during the past decade.

HLH-2004: Diagnostic and therapeutic guidelines for hemophagocytic lymphohistiocytosis

In HLH-94, the first prospective international treatment study for hemophagocytic lymphohistiocytosis (HLH), diagnosis was based on five criteria (fever, splenomegaly, bicytopenia, hypertriglyceridemia and/or hypofibrinogenemia, and hemophagocytosis). In HLH-2004 three additional criteria are introduced; low/absent NK-cell-activity, hyperferritinemia, and high-soluble interleukin-2-receptor levels. Altogether five of these eight criteria must be fulfilled, unless family history or molecular diagnosis is consistent with HLH. HLH-2004 chemo-immunotherapy includes etoposide, dexamethasone, cyclosporine A upfront and, in selected patients, intrathecal therapy with methotrexate and corticosteroids. Subsequent hematopoietic stem cell transplantation (HSCT) is recommended for patients with familial disease or molecular diagnosis, and patients with severe and persistent, or reactivated, disease. In order to hopefully further improve diagnosis, therapy and biological understanding, participation in HLH studies is encouraged.

Familial and acquired hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition of severe hyperinflammation caused by the uncontrolled proliferation of activated lymphocytes and histiocytes secreting high amounts of inflammatory cytokines. Cardinal signs and symptoms are prolonged fever, hepatosplenomegaly and pancytopenia. Characteristic biochemical markers include elevated triglycerides, ferritin and low fibrinogen. HLH occurs on the basis of various inherited or acquired immune deficiencies. Impaired function of natural killer (NK) cells and cytotoxic T-cells (CTL) is shared by all forms of HLH. Genetic HLH occurs in familial forms (FHLH) in which HLH is the primary and only manifestation, and in association with the immune deficiencies Chédiak-Higashi syndrome 1 (CHS 1), Griscelli syndrome 2 (GS 2) and x-linked lymphoproliferative syndrome (XLP), in which HLH is a sporadic event. Most patients with acquired HLH have no known underlying immune deficiency. Both acquired and genetic forms are triggered by infections, mostly viral, or other stimuli. HLH also occurs as a complication of rheumatic diseases (macrophage activation syndrome) and of malignancies. Several genetic defects causing FHLH have recently been discovered and have elucidated the pathophysiology of HLH. The immediate aim of therapy in genetic and acquired HLH is suppression of the severe hyperinflammation, which can be achieved with immunosuppressive/immunomodulatary agents and cytostatic drugs. Patients with genetic forms have to undergo stem cell transplantation to exchange the defective immune system with normally functioning immune effector cells. In conclusion, awareness of the clinical symptoms and of the diagnostic criteria of HLH is crucial in order not to overlook HLH and to start life-saving therapy in time.

Mutation spectrum in children with primary hemophagocytic lymphohistiocytosis: molecular and functional analyses of PRF1, UNC13D, STX11, and RAB27A

Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal-recessive disease that affects young children. It presents as a severe hyperinflammatory syndrome with activated macrophages and T lymphocytes. Mutations in the perforin 1 gene (PRF1) were found in FHL-2 in 15-50% of all cases. Defective granule exocytosis caused by mutations in the hMunc13-4 gene (UNC13D) has been described in FHL-3. FHL-4 patients have mutations in STX11, a t-SNARE involved in intracellular trafficking. We analyzed a large group of 63 unrelated patients with FHL of different geographic origins (Turkey:32; Germany:23; others:8) for mutations in STX11, PRF1, and UNC13D. We identified mutations in 38 samples (20 in PRF1, 12 in UNC13D, and six in STX11). Of 32 patients from Turkey, 14 had mutations in PRF1, six had mutations in UNC13D, and six had mutations in STX11. The mutation Trp374X in PRF1 was found in 12 patients from Turkey and was associated with a very early onset of the disease below the age of 3 months in all cases. In contrast, three of 23 and four of 23 patients from Germany, and three of eight and two of eight from other origins showed mutations in PRF1 and UNC13D, respectively, but none in STX11. Thus, FHL-2, FHL-3, and FHL-4 account for 80% of the HLH cases of Turkish origin, and for 30% of German patients. Furthermore, we identified mutations in RAB27A in three patients with FHL-related Griscelli syndrome type 2. In functional studies using a mammalian two-hybrid system we found that missense mutations Ala87Pro in Rab27a and Leu403Pro in hMunc13-4 each prevented the formation of a stable hMunc13-4/Rab27a complex in vitro. Our findings demonstrate extensive genetic and allelic heterogeneity in FHL and delineate an approach for functionally characterizing missense mutations in RAB27A and UNC13D.

Novel Munc13-4 mutations in children and young adult patients with haemophagocytic lymphohistiocytosis

Familial haemophagocytic lymphohistiocytosis (FHL) is a genetically heterogeneous disorder characterised by constitutive defects in cellular cytotoxicity resulting in fever, hepatosplenomegaly and cytopenia, and the outcome is fatal unless treated by chemoimmunotherapy followed by haematopoietic stem-cell transplantation. Since 1999, mutations in the perforin gene giving rise to this disease have been identified; however, these account only for 40% of cases. Lack of a genetic marker hampers the diagnosis, suitability for transplantation, selection of familial donors, identification of carriers, genetic counselling and prenatal diagnosis. Mutations in the Munc13-4 gene have recently been described in patients with FHL. We sequenced the Munc13-4 gene in all patients with haemophagocytic lymphohistiocytosis not due to PRF1 mutations. In 15 of the 30 families studied, 12 novel and 4 known Munc13-4 mutations were found, spread throughout the gene. Among novel mutations, 2650C-->T introduced a stop codon; 441del A, 532del C, 3082del C and 3226ins G caused a frameshift, and seven were mis sense mutations. Median age of diagnosis was 4 months, but six patients developed the disease after 5 years of age and one as a young adult of 18 years. Involvement of central nervous system was present in 9 of 15 patients, activity of natural killer cells was markedly reduced or absent in 13 of 13 tested patients. Chemo-immunotherapy was effective in all patients. Munc13-4 mutations were found in 15 of 30 patients with FHL without PRF1 mutations. Because these patients may develop the disease during adolescence or even later, haematologists should include FHL2 and FHL3 in the differential diagnosis of young adults with fever, cytopenia, splenomegaly and hypercytokinaemia.

Fetal and neonatal histiocytoses

PURPOSE

The histiocytoses are a group of disorders of the monophagocytic system having a variety of clinical and pathological findings. They occur less often during the perinatal period than later in life. Their biologic behavior, response to therapy, and histologic types are not the same.

METHODS

The study consisted of 221 fetuses and neonates collected from the literature and from personal files.

RESULTS

Langerhans' cell histiocytosis (LCH), the hemophagocytic lymphohistiocytoses (HLH), and juvenile xanthogranuloma (JXG), in order of rank, were the main histiocytoses occurring in the perinatal period. HLH accounted for the highest mortality (74%) followed by disseminated LCH (52%) and JXG (11%). All neonates with LCH and JXG limited to the skin and/or subcutaneous tissue survived with or without treatment.

CONCLUSIONS

This study suggests that there is an increased incidence of spontaneous regression of certain histiocytic lesions in neonates as compared to older individuals. Cutaneous forms JXG and LCH had the highest incidence of regression followed by infection associated HLH.

Hematopoietic stem cell transplantation in hemophagocytic lymphohistiocytosis: a single-center report of 48 patients

OBJECTIVES

Familial hemophagocytic lymphohistiocytosis (FHLH) is a genetically determined disorder characterized by the early onset of fever, hepatosplenomegaly, central nervous system disease, thrombocytopenia, coagulation disorders, and hemophagocytosis. It is caused by genetic defects that impair T cell-mediated and natural cytotoxicity. Chemotherapy- or immunotherapy-based treatments can achieve remission. Hematopoietic stem cell transplantation (HSCT), however, is the only curative option, but optimal modalities and long-term outcome are not yet well known.

METHODS

We retrospectively analyzed the outcome of HSCT that was performed in 48 consecutive patients who had FHLH and were treated in a single center between 1982 and 2004.

RESULTS

The overall survival was 58.5% with a median follow-up of 5.8 years and extending to 20 years. A combination of active disease and haploidentical HSCT had a poor prognosis because in this situation, HLH disease is more frequently associated with graft failure. Twelve patients received 2 transplants because of graft failure (n = 7) or secondary graft loss that led to HLH relapse (n = 5). Transplant-related toxicity essentially consisted in veno-occlusive disease, which occurred in 28% of transplants and was associated with young age, haploidentical transplantation, and the use of antithymocyte globulin (ATG) in the conditioning regimen. A sustained remission was achieved in all patients with a donor chimerism > or = 20% of leukocytes. Long-term sequelae were limited, because only 2 (7%) of 28 patients experienced a mild neurologic disorder.

CONCLUSIONS

This survey demonstrates the long-term efficacy of HSCT as a cure of FHLH. HSCT preserves quality of life. It shows that HSCT should be performed as early as a complete remission has been achieved. Additional studies are required to improve the procedure and reduce its toxic effects.

Review of hemophagocytic lymphohistiocytosis (HLH) in children with focus on Japanese experiences

Hemophagocytic lymphohistiocytosis (HLH) is characterized by fever and hepatosplenomegaly associated with pancytopenia, hypertriglyceridemia and hypofibrinogenemia. Increased levels of cytokines and impaired natural killer activity are biological markers of HLH. HLH can be classified into two distinct forms, including primary HLH, also referred to as familial hemophagocytic lymphohistiocytosis (FHL), and secondary HLH. Although FHL is an autosomal recessive disorder typically occurring in infancy, it is important to clarify that the disease may also occur in older patients. It is now considered that FHL is a disorder of T-cell function; moreover, clonal proliferation of T lymphocytes is observed in a few FHL patients, and cytotoxicity of these T lymphocytes for target cells is usually impaired. In 1999, perforin gene (PRF1) mutation was identified as a cause of 20-30% of FHL (FHL2) cases. In Japan, two specific mutations of PRF1 were also detected. Furthermore, in 2003, MUNC13-4 mutations were identified in some non-FHL2 patients (FHL3). Identification of other genes responsible for remaining cases is a major concern. Hematopoietic stem cell transplantation (HSCT) has been established as the only accepted curative therapy for FHL. Thus, appropriate diagnosis and prompt treatment with HSCT are necessary for FHL patients. Genetic analysis for PRF1 and MUNC13-4 and functional assay of cytotoxic T lymphocytes are recommended to be performed in each patient. In those patients displaying impaired cytotoxic function but lacking genetic defects, samples should be employed for identification of unknown genes. In the near future, an entire pathogenesis should be clarified in order to establish appropriate therapies including immunotherapy, HSCT and gene therapy.

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.

Haematopoietic stem cell transplantation in haemophagocytic lymphohistiocytosis

Haemophagocytic lymphohistiocytosis (HLH) poses major therapeutic challenges, and the primary inherited form, familial haemophagocytic lymphohistiocytosis (FHL), is usually fatal. We evaluated, including Cox regression analysis, survival in 86 children (29 familial) that received HLH-94-therapy (etoposide, dexamethasone, ciclosporin) followed by allogeneic stem cell transplantation (SCT) between 1995 and 2000. The overall estimated 3-year-survival post-SCT was 64% [confidence interval (CI) = +/-10%] (n = 86); 71 +/- 18% in those patients with a matched related donor (MRD, n = 24), 70 +/- 16% with a matched unrelated donor (MUD, n = 33), 50 +/- 24% with a family haploidentical donor (haploidentical, n = 16), and 54 +/- 27% with a mismatched unrelated donor (MMUD, n = 13). After adjustment for potential confounding factors, estimated odds ratios (OR) for mortality were 1.93 (CI =0.61-6.19) for MUD, 3.31 (1.02-10.76) for haploidentical, and 3.01 (0.91-9.97) for MMUD, compared with MRD. In children with active disease after 2-months of therapy (n = 43) the OR was 2.75 (1.26-5.99), compared with inactive disease (n = 43). In children with active disease at SCT (n = 37), the OR was 1.80 (0.80-4.06) compared with inactive disease (n = 49), after adjustment for disease activity at 2-months. Mortality was predominantly transplant-related. Most HLH patients survived SCT using MRD or MUD, and survival with partially mismatched donors was also acceptable. Patients that responded well to initial pretransplant-induction therapy fared best, but some persisting HLH activity should not automatically preclude performing SCT.

Allogeneic bone marrow transplantation for children with histiocytic disorders: use of TBI and omission of etoposide in the conditioning regimen

The histiocytoses are rare disorders of antigen-processing phagocytic or antigen-presenting cells. Allogeneic bone marrow transplantation (BMT) can be curative of these disorders. We report a series of five children with Langerhans cell histiocytosis (n=2) or hemophagocytic lymphohistiocytosis (n=3), who received allogeneic BMT with a total body irradiation (TBI)-containing regimen (TBI, cytarabine, and cyclophosphamide) at our institution between 1995 and 2000. One of these patients received busulfan, cyclophosphamide, and etoposide for the first of two BMTs. All grafts except one (a matched sibling-donor graft) were T-cell-depleted grafts from unrelated donors. All received cyclosporine graft-versus-host disease (GvHD) prophylaxis; the recipient of the matched sibling graft also received methotrexate. Three patients engrafted at a median of 24 days after transplantation. The patient who did not receive TBI experienced primary graft failure and recurrent disease. After the TBI-containing conditioning regimen was given, a second transplant engrafted on day +17. One patient with concurrent myelodysplastic syndrome died of toxicity on day +33 without evidence of engraftment. No acute or chronic GvHD was observed. Four patients survive disease-free, a median of 63 months after transplantation, all with Lansky performance scores of 100. We conclude that a conditioning regimen containing TBI but not etoposide is effective in allogeneic BMT for children with histiocytic diseases.

Successful engraftment and stable full donor chimerism after myeloablation with thiotepa, fludarabine, and melphalan and CD34-selected peripheral allogeneic stem cell transplantation in hemophagocytic lymphohistiocytosis

Allogeneic hematopoietic stem cell transplantation (HSCT) represents the only curative option for primary hemophagocytic lymphohistiocytosis (HLH), a rare disease of infants and young children, characterized by recurrent fever, hepatosplenomegaly, and cytopenia. We report a case of successful engraftment and stable full-donor chimerism in a patient with HLH who underwent peripheral allogeneic CD34-selected HSCT. The donor was his 1-antigen-HLA-mismatched grandmother. After a conditioning regimen based on the combination of thiotepa, fludarabine, melphalan, and rabbit antilymphocyte serum, the patient received a megadose of 26.3 x 10(6)/kg of CD34(+) peripheral blood cells. Neutrophil (>0.5 x 10(9)/L) and platelet (>50 x 10(9)/L) engraftment was observed on days +16 and +12, respectively, and the patient was discharged home on day +24. No acute or chronic GVHD was observed. Infectious complications were the main causes of re-hospitalization in the first year after transplantation, but no significant morbidity was observed thereafter. Thirty-two months after HSCT, the patient is alive and well, still in complete clinical remission of his underlying disease with a durable engraftment, normal NK activity and full donor chimerism. This case suggests that a fludarabine-based conditioning regimen and CD34-selected peripheral allogeneic HSCT may be a feasible option in case of unavailability of a fully HLA-matched related or unrelated donor.

Biology and treatment of familial hemophagocytic lymphohistiocytosis: importance of perforin in lymphocyte-mediated cytotoxicity and triggering of apoptosis

Familial hemophagocytic lymphohistiocytosis (FHL) is, without treatment, an invariably fatal disease of infancy and early childhood characterized by fever, hepatosplenomegaly, pancytopenia, and a widespread accumulation of T-lymphocytes and macrophages. During recent years, the diagnosis and the survival as well as the understanding of the disease have improved dramatically. Recent studies suggest that FHL is caused by impaired lymphocyte-mediated cytotoxicity and defective triggering of apoptosis, and that the symptoms are mediated by a pro-inflammatory hypercytokinemia. Moreover, specific genetic alterations, mutations in the perforin gene, have been revealed in FHL patients. Perforin, which normally is secreted from cytotoxic T-lymphocytes and natural killer (NK) cells upon conjugation between effector and target cells, is able to insert into the membrane of the target cell. It there polymerizes to form a cell death-inducing pore through which toxic granzymes may enter the cell and trigger apoptosis. The establishment of perforin deficiency as a cause of the rapidly fatal disease FHL has demonstrated the essential role of perforin in human immune homeostasis.

Outcome for children after failed transplant for primary haemophagocytic lymphohistiocytosis

Primary haemophagocytic lymphohistiocytosis is a rare disorder of childhood, which is usually fatal without allogeneic stem cell transplantation (SCT). For children who lack a matched family or closely matched unrelated donor, SCT using haploidentical parental stem cells has been used, but is associated with an increased risk of graft failure. The most appropriate subsequent management for those children who survive after graft rejection is currently unclear. We report the outcome for three such children. After a period of disease quiescence lasting 4 months to 8 years, disease recurrence and subsequent death occurred in each case. Accordingly, a second SCT is recommended.

Liver involvement in childhood histiocytic syndromes

The histiocytic syndromes of childhood are disorders of the reticuloendothelial system with variable clinical manifestations. Included among them are Langerhans cell histiocytosis and hemophagocytic lymphohistiocytosis. This discussion will be restricted to these two disorders. Liver disease in these conditions is common. Langerhans cell histiocytosis is characterized by the abnormal clonal proliferation of the macrophage-derived Langerhans cell. Liver involvement at diagnosis has management and prognostic significance. In a subgroup of patients, sclerosing cholangitis develops, which may lead to end-stage liver disease requiring liver transplantation. Hemophagocytic lymphohistiocytosis is a disease of abnormally activated macrophages that can involve multiple organ systems, including the liver. Differentiation between this disorder and other causes of pediatric liver disease is critical, because treatment strategies include chemotherapy, immunosuppression, and frequently bone marrow transplantation.

Recent developments in the management of haemophagocytic lymphohistiocytosis

Over the past two decades, the underlying pathophysiology of haemophagocytic lymphohistiocytosis (HLH) (synonyms: haemophagocytic syndrome, macrophage activation syndrome) has been well recognised. Cytokine storm plays a major role, which derives from an inappropriate immune reaction caused by proliferating and activated T-cell or natural killer (NK) cells associated with macrophage activation and inadequate apoptosis of immunogenic cells. Many biological parameters reflecting activity of disease or response to treatment have been identified, in particular, serum ferritin has been confirmed to be one of the markers for HLH. The common types of HLH consist of non-hereditary (acquired) infection-associated disease such as Epstein-Barr virus (EBV)-haemophagocytic lymphohistiocytosis (HLH) and hereditary (familial) disease such as FHL, in which, at the molecular level, dysfunctional perforin was clarified. Regarding the therapeutic strategies, prompt differential diagnosis of underlying disease is essential and choice of treatment should be based on the risk (low or high) of prognosis, where either cyclosporin A, steroids or iv. immunoglobulin (IVIG) may be indicated as initial treatment for low-risk patients, with etoposide-containing regimens for high-risk patients. Significant improvement of prognosis has been obtained by incorporating intensive supportive care at the disease onset and prompt introduction of immunosuppressants to control cytokine storm. Subsequent immunochemotherapy and haemopoietic stem cell transplantation have contributed significantly to further improve survival of hereditary and refractory HLH patients.

Familial hemophagocytic lymphohistiocytosis: too little cell death can seriously damage your health

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare and fatal disease of early childhood characterized by a non-malignant accumulation of activated T lymphocytes and histiocytes in the reticuloendothelial system. Moreover, immune system derangement, with prominent hypercytokinemia and low or absent cytotoxic T and natural killer (NK) cell activity, is a consistent feature of this autosomal recessive disorder. Recent work has demonstrated that the degree of spontaneous caspase activation in FHL lymphocytes is attenuated in vitro whereas Fas-mediated caspase activation and apoptosis induction remains unmitigated, and FHL can thus be distinguished from the related chronic disorder of immune regulation termed autoimmune lymphoproliferative syndrome or ALPS. However, subsequent studies have identified mutations in the gene encoding perforin, a cytotoxic granule constituent required for apoptotic killing of target cells, in a number of FHL patients. Hence, the underlying defect in FHL may be conceived of as a lack of apoptosis triggering within the immune system, rather than apoptosis resistance per se. These observations represent an important step in our understanding of the pathogenesis of FHL and also serve to emphasize the pivotal role of cellular (perforin-based) cytotoxicity in the regulation of immune homeostasis.