Kai Lehmberg

A prospective evaluation of degranulation assays in the rapid diagnosis of familial hemophagocytic syndromes.

Familial hemophagocytic lymphohistiocytosis (FHL) is a life-threatening disorder of immune regulation caused by defects in lymphocyte cytotoxicity. Rapid differentiation of primary, genetic forms from secondary forms of hemophagocytic lymphohistiocytosis (HLH) is crucial for treatment decisions. We prospectively evaluated the performance of degranulation assays based on surface up-regulation of CD107a on natural killer (NK) cells and cytotoxic T lymphocytes in a cohort of 494 patients referred for evaluation for suspected HLH. Seventy-five of 77 patients (97%) with FHL3-5 and 11 of 13 patients (85%) with Griscelli syndrome type 2 or Chediak-Higashi syndrome had abnormal resting NK-cell degranulation. In contrast, NK-cell degranulation was normal in 14 of 16 patients (88%) with X-linked lymphoproliferative disease and in 8 of 14 patients (57%) with FHL2, who were identified by diminished intracellular SLAM-associated protein (SAP), X-linked inhibitor of apoptosis protein (XIAP), and perforin expression, respectively. Among 66 patients with a clinical diagnosis of secondary HLH, 13 of 59 (22%) had abnormal resting NK-cell degranulation, whereas 0 of 43 had abnormal degranulation using IL-2-activated NK cells. Active disease or immunosuppressive therapy did not impair the assay performance. Overall, resting NK-cell degranulation below 5% provided a 96% sensitivity for a genetic degranulation disorder and a specificity of 88%. Therefore, degranulation assays allow a rapid and reliable classification of patients, benefiting treatment decisions.

Hemophagocytic syndromes — An update

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome and not an independent disease. HLH represents the extreme end of a severe uncontrolled hyperinflammatory reaction that can occur in many underlying conditions. Genetic forms of HLHs are due to defects in transport, processing and function of cytotoxic granules in natural killer cells and cytotoxic T lymphocytes, and are not restricted to manifestation in childhood. Acquired forms of HLH are encountered in infections, autoinflammatory and autoimmune diseases, malignancies, acquired immune deficiency. Functional tests allow for differentiation between genetic and acquired HLH. Treatment aims at suppressing hypercytokinemia and eliminating activated and infected cells. It includes immunomodulatory and immunosuppressive agents, cytostatics, T-cell and cytokine antibodies. In genetic HLH cure can only be achieved with hematopoietic stem cell transplantation. Reduced-intensity conditioning regimens have considerably improved survival.

Clinical Features, Treatment, and Outcome of Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis: A Multinational, Multicenter Study of 362 Patients

To describe the clinical, laboratory, and histopathologic features, current treatment, and outcome of patients with macrophage activation syndrome (MAS) complicating systemic juvenile idiopathic arthritis (JIA).

X-linked inhibitor of apoptosis (XIAP) deficiency: the spectrum of presenting manifestations beyond hemophagocytic lymphohistiocytosis.

X-linked inhibitor of apoptosis (XIAP) deficiency caused by mutations in BIRC4 was initially described in patients with X-linked lymphoproliferative syndrome (XLP) who had no mutations in SH2D1A. In the initial reports, EBV-associated hemophagocytic lymphohistiocytosis (HLH) was the predominant clinical phenotype. Among 25 symptomatic patients diagnosed with XIAP deficiency, we identified 17 patients who initially presented with manifestations other than HLH. These included Crohn-like bowel disease (n=6), severe infectious mononucleosis (n=4), isolated splenomegaly (n=3), uveitis (n=1), periodic fever (n=1), fistulating skin abscesses (n=1) and severe Giardia enteritis (n=1). Subsequent manifestations included celiac-like disease, antibody deficiency, splenomegaly and partial HLH. Screening by flow cytometry identified 14 of 17 patients in our cohort. However, neither genotype nor protein expression nor results from cell death studies were clearly associated with the clinical phenotype. Only mutation analysis can reliably identify affected patients. XIAP deficiency must be considered in a wide range of clinical presentations.

Recent advances in the diagnosis and treatment of hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening disease of severe hyperinflammation caused by uncontrolled proliferation of activated lymphocytes and macrophages secreting high amounts of inflammatory cytokines. It is a frequent manifestation in patients with predisposing genetic defects, but can occur secondary to various infectious, malignant, and autoimmune triggers in patients without a known genetic predisposition. Clinical hallmarks are prolonged fever, cytopenias, hepatosplenomegaly, and neurological symptoms, but atypical variants presenting with signs of chronic immunodeficiency are increasingly recognized. Impaired secretion of perforin is a key feature in several genetic forms of the disease, but not required for disease pathogenesis. Despite progress in diagnostics and therapy, mortality of patients with severe HLH is still above 40%. Reference treatment is an etoposide-based protocol, but new approaches are currently explored. Key for a favorable prognosis is the rapid identification of an underlying genetic cause, which has been facilitated by recent immunological and genetic advances. In patients with predisposing genetic disease, hematopoietic stem cell transplantation is performed increasingly with reduced intensity conditioning regimes. Current research aims at a better understanding of disease pathogenesis and evaluation of more targeted approaches to therapy, including anti-cytokine antibodies and gene therapy.

Hemophagocytic lymphohistiocytosis: pathogenesis and treatment.

Hemophagocytic lymphohistiocytosis (HLH) is not an independent disease but rather a life-threatening clinical syndrome that occurs in many underlying conditions and in all age groups. HLH is the consequence of a severe, uncontrolled hyperinflammatory reaction that in most cases is triggered by an infectious agent. Persistent stimulation of lymphocytes and histiocytes results in hypercytokinemia, leading to the characteristic symptoms of HLH. Genetic defects in familial HLH and in immunodeficiency syndromes associated with albinism affect the transport, processing, and function of cytotoxic granules in natural killer cells and cytotoxic T lymphocytes. This leads to defective killing of target cells and a failure to contract the immune response. The defects are increasingly found also in adolescents and adults. Acquired HLH occurs in autoinflammatory and autoimmune diseases (macrophage activation syndrome) and in patients with iatrogenic immunosuppression or with malignancies, but also in otherwise healthy persons with infections. Treatment of HLH aims at suppressing hypercytokinemia and eliminating the activated and infected cells. In genetic HLH, hematopoietic stem cell transplantation (HSCT) is needed for the correction of the immune defect. Treatment modalities include immunosuppressive, immunomodulatory, and cytostatic drugs; T-cell antibodies; and anticytokine agents. Using immunochemotherapy, familial HLH, which had been invariably fatal, has become a curable disease with more than 50% survivors. Reduced intensity conditioning for HSCT, which is associated with less transplantation-related mortality, will further improve cure rates.

Distinct mutations in STXBP2 are associated with variable clinical presentations in patients with familial hemophagocytic lymphohistiocytosis type 5 (FHL5)

Familial hemophagocytic lymphohistiocytosis (FHL) is a genetically determined hyperinflammatory syndrome caused by uncontrolled immune response mediated by T-lymphocytes, natural killer (NK) cells, and macrophages. STXBP2 mutations have recently been associated with FHL5. To better characterize the genetic and clinical spectrum of FHL5, we analyzed a cohort of 185 patients with suspected FHL for mutations in STXBP2. We detected biallelic mutations in 37 patients from 28 families of various ethnic origins. Missense mutations and mutations affecting 1 of the exon 15 splice sites were the predominant changes detectable in this cohort. Patients with exon 15 splice-site mutations (n = 13) developed clinical manifestations significantly later than patients with other mutations (median age, 4.1 year vs 2 months) and showed less severe impairment of degranulation and cytotoxic function of NK cells and CTLs. Patients with FHL5 showed several atypical features, including sensorineural hearing deficit, abnormal bleeding, and, most frequently, severe diarrhea that was only present in early-onset disease. In conclusion, we report the largest cohort of patients with FHL5 so far, describe an extended disease spectrum, and demonstrate for the first time a clear genotype-phenotype correlation.

2016 Classification Criteria for Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis: A European League Against Rheumatism/American College of Rheumatology/Paediatric Rheumatology International Trials Organisation Collaborative Initiative

To develop criteria for the classification of macrophage activation syndrome (MAS) in patients with systemic juvenile idiopathic arthritis (JIA).

Allogeneic hematopoietic cell transplantation for XIAP deficiency: an international survey reveals poor outcomes

There have been no studies on patient outcome after allogeneic hematopoietic cell transplantation (HCT) in patients with X-linked inhibitor of apoptosis (XIAP) deficiency. To estimate the success of HCT, we conducted an international survey of transplantation outcomes. Data were reported for 19 patients. Seven patients received busulfan-containing myeloablative conditioning (MAC) regimens. Eleven patients underwent reduced intensity conditioning (RIC) regimens predominantly consisting of alemtuzumab, fludarabine, and melphalan. One patient received an intermediate-intensity regimen. Survival was poor in the MAC group, with only 1 patient surviving (14%). Most deaths were from transplantation-related toxicities, including venoocclusive disease and pulmonary hemorrhage. Of the 11 patients who received RIC, 6 are currently surviving at a median of 570 days after HCT (55%). Preparative regimen and HLH activity affected outcomes, and of RIC patients reported to be in remission from HLH, survival is 86% (P = .03). We conclude that MAC regimens should not be used for patients with XIAP deficiency. It is possible that the loss of XIAP and its antiapoptotic functions contributes to the high incidence of toxicities observed with MAC regimens. RIC regimens should be pursued with caution and, if possible, efforts should be made to ensure HLH remission before HCT in these patients.

Diagnostic evaluation of patients with suspected haemophagocytic lymphohistiocytosis.

Haemophagocytic lymphohistiocytosis (HLH) is a life‐threatening hyperinflammatory syndrome characterized by severely disturbed immune homeostasis. It can affect all age groups. Diagnostic evaluation of the patient with suspected HLH has to address three main questions: (i) does the patient have HLH? There is no simple diagnostic test, but a number of clinical and laboratory criteria define this clinical syndrome. (ii) Can a trigger be identified? A variety of infections, malignant or autoimmune diseases can contribute to the disturbed immune homeostasis with important consequences for treatment. (iii) Does the patient suffer from a genetic disease predisposing to HLH? Recent advances in the understanding of the genetic and pathophysiological basis of HLH have enabled a better and more rapid answer to this question, which is relevant for prognosis and the decision to perform haematopoietic stem cell transplantation. This review summarizes the current diagnostic approach to the patient with HLH.