Episodes Of Hemophagocytic Lymphohistiocytosis Research Articles

X-Linked Lymphoproliferative Syndrome: A Spectrum of Clinical and Immunological Profile and Novel Pathogenic Variants from Chandigarh, India

Introduction: X-linked lymphoproliferative syndrome (XLP) is a rare primary immune deficiency. Two types of XLP have been described: XLP-1 and XLP-2. Methods: We found 7 patients with XLP (3 had XLP-1 and 4 had XLP-2) after reviewing the data from Pediatric Immunodeficiency Clinic from 1997 to 2021. Results: Mean age at diagnosis was 3.8 years, and mean delay in diagnosis was 2.6 years. Five patients had recurrent episodes of infections. Four patients developed at least one episode of hemophagocytic lymphohistiocytosis (HLH) (2 with XLP-1 and 2 with XLP-2). Of these, 2 had recurrent HLH (both with XLP-2). Epstein-Barr virus (EBV) infection was detected in 2 (1 with XLP-1 and 1 with XLP-2). Both these patients had HLH. One child with XLP-2 had inflammatory bowel disease. Hypogammaglobulinemia was seen in 3 (2 with XLP-1 and 1 with XLP-2). Genetic analysis showed previously reported variants in 5, while 2 had novel variants (one in exon 7 of XIAP gene [c.1370dup p.Asn457Lysfs Ter16] and other had splice site variant in intron 1 of SH2D1A gene [c.138-2_138-1insG]). Episodes of HLH were managed with intravenous immunoglobulin (IVIg), methylprednisolone, oral prednisolone, cyclosporine, and rituximab. Inflammatory bowel disease was managed using oral prednisolone and azathioprine. One patient underwent haploidentical hematopoietic stem cell transplantation. One child with XLP-2 and WAS died because of fulminant pneumonia. Discussion/Conclusions: XLP should be considered as a strong possibility in any patient with features of HLH, repeated infections with hypogammaglobulinemia, persistent EBV infection, and early-onset IBD.

Salvage Therapy and Allogeneic Hematopoietic Cell Transplantation for the Severe Cytokine Storm Syndrome of Hemophagocytic Lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) can be considered as a severe cytokine storm syndrome disorder. HLH typically manifests as a life-threatening inflammatory syndrome characterized by fevers, cytopenias, hepatosplenomegaly, and various other accompanying manifestations such as coagulopathy, hepatitis or liver failure, seizures or altered mental status, and even multi-organ failure. Standard up-front treatments do not always bring HLH into remission or maintain adequate response, and salvage or alternative therapies are often needed. For patients with genetic diseases that cause HLH, curative allogeneic hematopoietic cell transplantation is usually offered to prevent future episodes of life-threatening HLH. Here, we will discuss the options and approaches for salvage therapy and hematopoietic cell transplantation for patients with HLH.

An analysis of reported cases of hemophagocytic lymphohistiocytosis (HLH) after COVID-19 vaccination

ABSTRACT Although COVID-19 vaccines are an effective public health tool to combat the global pandemic, serious adverse events, such as hemophagocytic lymphohistiocytosis (HLH), caused by them are a concern. In this systematic review, cases of HLH reported after COVID-19 vaccination have been examined to understand the relationship between the two and propose effective therapeutic strategies. Furthermore, ruxolitinib’s potential as a cytokine inhibitor and its affinity for CD25 were initially assessed through molecular docking, aiming to aid targeted HLH therapy. PubMed and Web of Science databases were searched for published individual case reports on the occurrence of HLH after the administration of any COVID-19 vaccine. A total of 17 articles (25 patients) were included in this qualitative analysis. Furthermore, molecular docking was employed to investigate the therapeutic potential of ruxolitinib for HLH after COVID-19 vaccination. The mean age of patients who developed HLH after COVID-19 vaccination was 48.1 years. Most HLH episodes occurred after the BNT162b2 mRNA COVID-19 vaccination (14/25 cases) and to an extent after the ChAdOx1 nCov‐19 vaccination (5/25 cases). Almost all affected patients received steroid and antibiotic therapy. Three patients died despite treatment because of esophagus rupture, neutropenic fever, bacteroides bacteremia, refractory shock, and encephalopathy and shock. Visual docking results of IL-2 Rα and ruxolitinib using the Discovery Studio 2019 Client software yielded a model score of 119.879. The findings highlight the importance of considering and identifying the adverse effects of vaccination and the possibility of using ruxolitinib for treating HLH after COVID-19 vaccination.

Elevated monocyte HLA-DR in pediatric secondary hemophagocytic lymphohistiocytosis: a retrospective study.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition, and its diagnosis may be challenging. In particular, some cases show close similarities to sepsis (fever, organ failure, and high ferritin), but their treatment, while urgent, differ: prompt broad-spectrum antibiotherapy for sepsis and immunosuppressive treatment for HLH. We questioned whether monocyte human leucocyte antigen (mHLA)-DR could be a diagnostic marker for secondary HLH (sHLH). We retrospectively reviewed data from patients with a sHLH diagnosis and mHLA-DR quantification. mHLA-DR data from healthy children and children with septic shock, whose HLA-DR expression is reduced, from a previously published study were also included for comparison. Six patients with sHLH had mHLA-DR quantification. The median level of monocyte mHLA-DR expression in patients with sHLH [79,409 antibodies bound per cell (AB/C), interquartile range (IQR) (75,734-86,453)] was significantly higher than that in healthy children and those with septic shock (29,668 AB/C, IQR (24,335-39,199), and 7,493 AB/C, IQR (3,758-14,659), respectively). Each patient with sHLH had a mHLA-DR higher than our laboratory normal values. Four patients had a second mHLA-DR sampling 2 to 4 days after the initial analysis and treatment initiation with high-dose corticosteroids; for all patients, mHLA-DR decreased to within or close to the normal range. One patient with systemic juvenile idiopathic arthritis had repeated mHLA-DR measurements over a 200-day period during which she underwent four HLH episodes. mHLA-DR increased during relapses and normalized after treatment incrementation. In this small series, mHLA-DR was systematically elevated in patients with sHLH. Elevated mHLA-DR could contribute to sHLH diagnosis and help earlier distinction with septic shock.

Insights into the Natural History and Treatment Outcomes of Hemophagocytic Lymphohistiocytosis (HLH): The into-HLH Registry

Purpose: Hemophagocytic Lymphohistiocytosis (HLH) is a complex, hyperinflammatory syndrome resulting from the interplay of genetic predisposition and various environmental factors. In the last 25 years, scientific insights and treatments have evolved substantially with novel targeted therapies. However, approximately 30% of patients do not respond to therapy despite available treatment options. Thus, there is an unmet need for a deeper understanding of the natural history, clinical/ etiologic diversity, complications, and treatment outcomes of HLH patients, specifically from North America. Therefore, we established a robust registry to better understand the natural history, treatment patterns, and outcomes of HLH syndrome. Methods: To address these knowledge gaps, we established a non-interventional, observational study with a dual-enrollment method for maximum engagement (NCT05277272) modeled after the ACCELERATE Castleman disease natural history registry. Patients are consented and enrolled in the study via the traditional Physician Driven Arm (PDA) and a Patient-Powered Arm (PPA), in which patients are directly recruited through the Registry's website (www.hlhregistry.org). The Registry is a collaboration between Cincinnati Children's Hospital Medical Center (the academic sponsor), Texas Children's Hospital, The North American Consortium for Histiocytosis (NACHO), and Sobi Inc. (the industry sponsor). Anticipated enrollment is > 200 patients with clinically suspected or confirmed HLH, including familial and all other subtypes of HLH. Medical records are acquired and abstracted by the INTO-HLH Registry Team (IHRT) at Cincinnati Children's Hospital Medical Center into pre-specified electronic case report forms (eCRF). HLH-related data is abstracted from initial disease presentation to diagnosis, through treatment until Hematopoietic Stem Cell Transplantation (HSCT) or end of HLH-directed treatments. Patients are followed for at least five years to assess short- and long-term outcomes. Discrete HLH episodes are captured separately. Physicians at the PDA sites perform minimal data abstraction reflecting their subjective narrative regarding patients' treatments and responses. In addition, the patients are offered to answer optional patient-reported outcomes questionnaires and participate in correlative biology studies. The INTO-HLH steering committee adjudicates specific diagnoses and reviews adverse treatment events and causes of mortality. Results: Enrollment is ongoing with pediatric patients with familial HLH and adult patients with other subtypes of HLH already consented. The primary objective of the research is to describe the natural history of patients with HLH, and the secondary objective is to describe treatment patterns, responses, and outcomes. In addition, health-related quality of life, disease-related health burden, and the relationship between biologic variability and clinical outcomes will be assessed as exploratory objectives. Conclusion: The INTO-HLH Registry aims to advance clinical understanding and improve treatment outcomes in patients with HLH. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Recurrent parvovirus B19 viremia resulting in two episodes of hemophagocytic lymphohistiocytosis

BackgroundHemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory condition with uncontrolled activation of lymphocytes and macrophages. Besides a primary (genetic) form, HLH can also be triggered by malignant, autoimmune and infectious diseases. HLH recurrences are rarely described, usually only in primary HLH. Parvovirus B19 (PVB19) Infection is one of the rare and rather benign causes of HLH. Since the infection usually results in long-lasting immunity, recurrent viremia is very uncommon.Case presentationWe report an unusual case of a young female with recurrent PVB19 infection that led to repeated episodes of HLH. The first episode occurred at the age of 25 years with a three-week history of high fever and nonspecific accompanying symptoms. The diagnosis of HLH was confirmed by HLH-2004 criteria and HScore, PVB19 viremia was detected as underlying cause. Following guideline-based therapy, the patient was symptom-free for one year, before similar symptoms recurred in a milder form. Again, PVB19 was detected and HLH was diagnosed according to HScore. After successful treatment and a nine-month symptom-free interval, a third phase of hyperinflammation with low PVB19 viremia occurred; this time, treatment with a corticosteroid and intravenous immunoglobulin was initiated before the presence of clear diagnostic criteria for HLH. No further events occurred in the following three years.ConclusionsIn the case of our patient, the recurrent viremia triggered three episodes of hyperinflammation, two of which were clearly diagnosed as HLH. To our knowledge, this is the first published case of recurrent HLH due to PVB19 infection. Therefore, the case gives new insights in triggering mechanisms for HLH.

Case Report: Characterizing the Role of the STXBP2-R190C Monoallelic Mutation Found in a Patient With Hemophagocytic Syndrome and Langerhans Cell Histiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory disorder. HLH can be considered as a threshold disease depending on the trigger and the residual NK-cell cytotoxicity. In this study, we analyzed the molecular and functional impact of a novel monoallelic mutation found in a patient with two episodes of HLH. A 9-month-old child was diagnosed at 2 months of age with cutaneous Langerhans cell histiocytosis (LCH). After successful treatment, the patient developed an HLH episode. At 16 month of age, the patient went through an HSCT losing the engraftment 5 months later concomitant with an HLH relapse. The genetic study revealed a monoallelic mutation in the STXBP2 gene (.pArg190Cys). We transfected COS7 cells to analyze the STXBP2-R190C expression and to test the interaction with STX11. We used the RBL-2H3 cell line expressing STXBP2-WT-EGFP or R190C-EGFP for degranulation assays. Mutation STXBP2-R190C did not affect protein expression or interaction with syntaxin-11. However, we have demonstrated that STXBP2-R190C mutation diminishes degranulation in the RBL-2H3 cell line compared with the RBL-2H3 cell line transfected with STXBP2-WT or nontransfected. These results suggest that STXBP2-R190C mutation acts as a modifier of the degranulation process producing a decrease in degranulation. Therefore, under homeostatic conditions, the presence of one copy of STXBP2-R190 could generate sufficient degranulation capacity. However, it is likely that early in life when adaptive immune system functions are not sufficiently developed, an infection may not be resolved with this genetic background, leading to a hyperinflammation syndrome and eventually develop HLH. This analysis highlights the need for functional testing of new mutations to validate their role in genetic susceptibility and to establish the best possible treatment for these patients.

Transfusion Dependence Is Common in Adults with Hemophagocytic Lymphohistiocytosis (HLH) and Is Associated with EBV Viremia

Introduction:HLH in adults is a fulminant, often fatal hyperinflammatory disorder that often mimics sepsis and is associated with significant cytopenias, primary and secondary infections, immunosuppression, and bleeding. The etiologies in adults are typically autoimmune disease or lymphoma. As a result, HLH patients are immunocompromised hosts who represent a distinct group of high blood product users. Importantly, the need for adequate blood product support can obligate care in tertiary or quaternary settings. The literature lacks sufficient description of transfusion need patterns and the factors associated with blood product use in HLH. This IRB approved resource utilization study investigates this unique group of patients' transfusion needs and seeks to identify factors associated significant cytopenias that result in transfusion dependence.Methods: We retrospectively identified and reviewed the charts of 59 HLH patients diagnosed between January 2012 and May 2017 at Stanford Health Care system. Patients were identified by search of the ICD9 code 288.4, ICD 10 76.1, 76.2 and associated keyword searches Hemophagocytic Syndromes in the EPIC electronic medical record system and by a similar keyword permutation search in PowerPath, the pathology department database. Data collected and evaluated included the patients' demographics, causes of HLH, transfusion requirements, primary and secondary infections, Charleston comorbidity index, SOFA score, times to diagnosis and therapy, HLH therapy, lengths of hospital stay, and survivorship. Data related to transfusion therapy was restricted to active HLH episodes only and was not collected after remission. Statistical analysis utilized Fisher exact test or 2 tailed t-test.Results: The median age of the patients was 52 (range 18-96; SD +/- 19). The majority of the patients had either malignancy or autoimmune disease: 56% had underlying malignancy with lymphoma in 88%; 22% had an underlying autoimmune disease. A concurrent infectious component was common and found in 17/33 of malignancy and 9/14 autoimmune patients. Eighty-five (85) % (50/59) of the patients received blood products, with the transfusion requirements per hospitalization as following, in units: PRBC , mean 7, median 4 (range 0-68); platelets, mean 7, median 2 (range 0-37); FFP mean 2, median 0 (range 0-13), and pooled cryoprecipitate mean 2, median 0 (range 0-13). Adult patients with EBV viremia (24/59) showed the highest rate of transfusion (92%), with a statistically significant increase in platelet and cryoglobulin usage amongst transfused patients (p = 0.008 and p = 0.04, respectively).Conclusions: This analysis finds that a high percentage of adult patients with HLH require transfusions. Our data suggests that adult HLH secondary to an infectious etiology, in particular EBV viremia, correlates with higher blood product usage. Further multi-center studies with larger number of patients are needed to further characterize and optimize transfusion therapy in the management of adults with HLH, as well as to establish the potential role of transfusion therapy of these immunocompromised hosts in the need to provide tertiary or quaternary care. DisclosuresNo relevant conflicts of interest to declare.

Difficult Balance Between EBV Treatment and Posttransplant Immunosuppression: A Successful Transplant in a Child With Recurrent Epstein-Barr Virus–Induced Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening clinical syndrome. HLH can be classified into 2 major forms: primary and secondary. Viral infections are frequently implicated in the onset of active HLH episodes. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative treatment for primary HLH and refractory/relapsed HLH after proper chemoimmunotherapy, although following immunosuppressive therapy may lead to infectious complications, including viral infections. We report a case of a 6-year-old boy with Epstein-Barr virus (EBV)-induced hemophagocytic lymphohistiocytosis. The patient underwent an allo-HSCT from a 10/10 HLA-matched unrelated donor. Because he received myeloablative and immunosuppressive treatment, another EBV reactivation occurred, as well as cytomegalovirus (CMV) reactivation. After antiviral therapy, on day +27, elimination of EBV and CMV was achieved. Repeated chimerism tests evaluated decreasing donor chimerism; graft-versus-host disease prophylaxis was reduced from day +32 and eventually withdrawn. Later on, the patient developed acute graft-versus-host disease (skin rush, gastrointestinal dysfunction). Immunosuppressive agents (methylprednisolone, cyclosporine) were applied once again, which led to an increase of CMV viremia and polyomavirus (BK virus) primary infection. Virus infection can induct a severe disorder, such as HLH, and recur after its treatment. We believe our case represents dynamic changes in immunologic reaction to viral infection, which depend on modifications in treatment after allo-HSCT. These observations underscore the importance and difficulty of balancing immunosuppressive therapy and infection control.

Griscelli Syndrome Type 2 Sine Albinism: Unraveling Differential RAB27A Effector Engagement.

Griscelli syndrome type 2 (GS-2) is an inborn error of immunity characterized by partial albinism and episodes of hemophagocytic lymphohistiocytosis (HLH). It is caused by RAB27A mutations that encode RAB27A, a member of the Rab GTPase family. RAB27A is expressed in many tissues and regulates vesicular transport and organelle dynamics. Occasionally, GS-2 patients with RAB27A mutation display normal pigmentation. The study of such variants provides the opportunity to map distinct binding sites for tissue-specific effectors on RAB27A. Here we present a new case of GS-2 without albinism (GS-2 sine albinism) caused by a novel missense mutation (Val143Ala) in the RAB27A and characterize its functional cellular consequences. Using pertinent animal cell lines, the Val143Ala mutation impairs both the RAB27A–SLP2-A interaction and RAB27A–MUNC13-4 interaction, but it does not affect the RAB27A–melanophilin (MLPH)/SLAC2-A interaction that is crucial for skin and hair pigmentation. We conclude that disruption of the RAB27A–MUNC13-4 interaction in cytotoxic lymphocytes leads to the HLH predisposition of the GS-2 patient with the Val143Ala mutation. Finally, we include a review of GS-2 sine albinism cases reported in the literature, summarizing their genetic and clinical characteristics.

A Novel BTK Gene Mutation in a Child With Atypical X-Linked Agammaglobulinemia and Recurrent Hemophagocytosis: A Case Report

X-linked agammaglobulinemia (XLA), caused by a mutation in the Bruton's tyrosine kinase (BTK) gene, is rarely reported in patients with recurrent hemophagocytic lymphohistiocytosis (HLH). This mutation leads to significantly reduced numbers of circulatory B cells and serum immunoglobulins in patients. Therefore, they exhibit repetitive bacterial infections since infancy, and immunoglobulin (Ig) replacement therapy is the primary treatment. HLH is a life-threatening condition with manifestations of non-remitting fever, hepatosplenomegaly, cytopenias, coagulopathy, lipid disorder, and multiple organ failure. It is caused by the immune dysregulation between cytotoxic T cells, NK cells, and histiocytes. The treatment is based on HLH-2004 protocol including immunotherapy, chemotherapy, supportive therapy, and stem cell transplantation. However, as we know more about the classification and pathophysiology of HLH, the treatment is modified. T-cell-directed immunotherapy is effective in patients with primary HLH, and strong immunosuppression is contraindicated in patients with severe ongoing infections or some primary immunodeficiency diseases (PIDs). Here, we report the case of a 7-year-old boy who presented with ecthyma gangrenosum and several episodes of pyogenic infections during childhood. At the age of 5 years, he exhibited cyclic HLH every 2–3 months. The remission of HLH episodes finally achieved after he received monthly Ig replacement therapy (400 mg/kg) at the 4th HLH. However, transient elevation of IgM was incidentally discovered after 6 cycles of monthly Ig replacement therapy. IgM-secreting multiple myeloma, Waldenström's macroglobulinemia, and lymphoma were excluded. The IgM levels then declined and returned to the normal range within a year. The patient and his parents received whole-genome sequencing analysis. It revealed a novel hemizygous c.1632-1G>A mutation in the BTK gene and XLA was diagnosed. XLA exhibits a spectrum of clinical and immunological presentations in patients. The identification of the mutation in the BTK gene contribute to an accurate diagnosis. Ig replacement therapy is the primary treatment for HLH in patients with XLA.

How Viruses Contribute to the Pathogenesis of Hemophagocytic Lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening, hyperinflammatory syndrome, characterized by the uncontrolled activation of macrophages and T cells, eliciting key symptoms such as persistent fever, hepatosplenomegaly, pancytopenia, hemophagocytosis, hyperferritinemia, and coagulopathy. Viral infections are frequently implicated in the onset of active HLH episodes, both in primary, genetic HLH as in the secondary, acquired form. Infections with herpesviruses such as Epstein–Barr virus and cytomegalovirus are the most common. In autoimmune diseases, a link between viral infections and autoreactive immune responses has been recognized for a considerable time. However, the mechanisms by which viruses contribute to HLH pathogenesis remain to be clarified. In this viewpoint, different factors that may come into play are discussed. Viruses, particularly larger DNA viruses such as herpesviruses, are potent modulators of the immune response. By evading immune recognition, interfering with cytokine balances and inhibiting apoptotic pathways, viruses may increase the host’s susceptibility to HLH development. In particular cases, a direct connection between the viral infection and inhibition of natural killer cell or T cell cytotoxicity was reported, indicating that viruses may create immunological deficiencies reminiscent of primary HLH.

Spectrum of Atypical Clinical Presentations in Patients with Biallelic PRF1 Missense Mutations

Perforin, encoded by PRF1, is a pore-forming protein crucial for lymphocyte cytotoxicity. Biallelic PRF1 nonsense mutations invariably result in early-onset hemophagocytic lymphohistiocytosis (HLH), termed familial HLH type 2 (FHL2). In contrast, biallelic PRF1 missense mutations may give rise to later-onset disease and more variable manifestations. We retrospectively searched our database for patients from families with siblings carrying biallelic PRF1 missense mutations where at least one sibling did not develop HLH, and for patients with biallelic PRF1 missense mutations and an atypical presentation of disease. We reviewed their clinical, genetic, and immunological characteristics. In all, we identified 10 such patients, including three sibling pairs with discordant manifestations. Interestingly, in two families, siblings of late-onset HLH patients developed Hodgkin lymphoma but no HLH. In a third family, one sibling presented with recurrent HLH episodes, whereas the other remains healthy. Of note, the affected sibling also suffered from systemic lupus erythematosus. Additional unrelated patients with biallelic PRF1 missense mutations were affected by neurological disease without classical signs of HLH, gastrointestinal inflammation as initial presentation of disease, as well as a hematological malignancy. Compared to early-onset FHL2 patients, the patients with an atypical presentation displayed a partial recovery of NK cell cytotoxicity upon IL-2 stimulation in vitro. Our findings substantiate and expand the spectrum of clinical presentations of perforin deficiency, linking PRF1 missense mutations to lymphoma susceptibility and highlighting clinical variability within families. PRF1 mutations should, therefore, be considered as a cause of several diseases disparate to HLH.

The syndrome of hemophagocytic lymphohistiocytosis in primary immunodeficiencies: implications for differential diagnosis and pathogenesis.

Hemophagocytic lymphohistiocytosis is a hyperinflammatory syndrome defined by clinical and laboratory criteria. Current criteria were created to identify patients with familial hemophagocytic lmyphohistiocytosis in immediate need of immunosuppressive therapy. However, these criteria also identify patients with infection-associated hemophagocytic inflammatory states lacking genetic defects typically predisposing to hemophagocytic lymphohistiocytosis. These patients include those with primary immunodeficiencies, in whom the pathogenesis of the inflammatory syndrome may be distinctive and aggressive immunosuppression is contraindicated. To better characterize hemophagocytic inflammation associated with immunodeficiencies, we combined an international survey with a literature search and identified 63 patients with primary immunodeficiencies other than cytotoxicity defects or X-linked lymphoproliferative disorders, presenting with conditions fulfilling current criteria for hemophagocytic lymphohistiocytosis. Twelve patients had severe combined immunodeficiency with <100/μL T cells, 18 had partial T-cell deficiencies; episodes of hemophagocytic lymphohistiocytosis were mostly associated with viral infections. Twenty-two patients had chronic granulomatous disease with hemophagocytic episodes mainly associated with bacterial infections. Compared to patients with cytotoxicity defects, patients with T-cell deficiencies had lower levels of soluble CD25 and higher ferritin concentrations. Other criteria for hemophagocytoc lymphohistiocytosis were not discriminative. Thus: (i) a hemophagocytic inflammatory syndrome fulfilling criteria for hemophagocytic lymphohistiocytosis can be the initial manifestation of primary immunodeficiencies; (ii) this syndrome can develop despite severe deficiency of T and NK cells, implying that the pathophysiology is distinct and not appropriately described as "lympho"-histiocytosis in these patients; and (iii) current criteria for hemophagocytoc lymphohistiocytosis are insufficient to differentiate hemophagocytic inflammatory syndromes with different pathogeneses. This is important because of implications for therapy, in particular for protocols targeting T cells.

Immunologic Difference between Hypersensitivity to Mosquito Bite and Hemophagocytic Lymphohistiocytosis Associated with Epstein-Barr Virus Infection

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening, virus-triggered immune disease. Hypersensitivity to mosquito bite (HMB), a presentation of Chronic Active Epstein-Barr Virus infection (CAEBV), may progress to HLH. This study aimed to investigate the immunologic difference between the HMB episodes and the HLH episodes associated with EBV infection. Immunologic changes of immunoglobulins, lymphocyte subsets, cytotoxicity, intracellular perforin and granzyme expressions, EBV virus load and known candidate genes for hereditary HLH were evaluated and compared. In 12 HLH episodes (12 patients) and 14 HMB episodes (4 patients), there were both decreased percentages of CD4+ and CD8+ and increased memory CD4+ and activated (CD2+HLADR+) lymphocytes. In contrast to HMB episodes that had higher IgE levels and EBV virus load predominantly in NK cells, those HLH episodes with virus load predominantly in CD3+ lymphocyte had decreased perforin expression and cytotoxicity that were recovered in the convalescence period. However, there was neither significant difference of total virus load in these episodes nor candidate genetic mutations responsible for hereditary HLH. In conclusion, decreased perforin expression in the HLH episodes with predominant-CD3+ EBV virus load is distinct from those HMB episodes with predominant-NK EBV virus load. Whether the presence of non-elevated memory CD4+ cells or activated lymphocytes (CD2+HLADR+) increases the mortality rate in the HLH episodes remains to be further warranted through larger-scale studies.

Specificity of cytokine abnormalities in HLH

Hemophagocytic lymphohistiocytosis (HLH) is both under-recognized and over-diagnosed currently. Despite the use of the revised criteria for diagnosis, established by the Histiocyte Society in 2004, it seems that patients with severe infections, as well as patients with severe underlying rheumatologic and oncologic conditions receiving modern therapies (in whom HLH, or macrophage activation syndrome, can indeed occur), can meet criteria without a convincing “fit” for the clinician (Pediatr Blood Cancer 2007;48:124-31). On the other hand, especially early in the course in previously healthy younger children, HLH sometimes seems to be the “best diagnosis” even though laboratory criteria are not met fully. Accuracy of diagnosis is critical because therapy for HLH is either extremely helpful in abrogating an abnormal inflammatory response if the diagnosis is correct, or extremely harmful in impeding an appropriate response if the diagnosis is incorrect, especially when infection is the sole or predominant pathology.In a particularly robust study, Xu et al evaluated 756 consecutive patients with fever hospitalized in the Hematology/Oncology Unit of the Children's Hospital of Zhejiang University School of Medicine between 2005 and 2010, categorized the etiologies of fever, and also studied three control groups of 202 patients with hematology/oncology conditions without fever, 100 healthy children, and 85 previously healthy children with confirmed bacterial sepsis. Multiplex Th1/Th2 cytokine kit assay was used to measure serum concentrations of defined interleukins (IL), tumor necrosis factors, and interferon.The 71 episodes of HLH showed a highly discriminating cytokine pattern of uniquely highly elevated IFN-γ level (94% sensitivity and 97% specificity for HLH using a cutoff point of 100 pg/mL) and IL-10 level, but only modestly elevated IL-6 level. Combined use of IFN-γ level >75 pg/mL plus IL-10 >60 pg/mL had sensitivity of 93% and specificity of 99% for HLH.The authors point out limitations of the study, as well as the heterogeneity of HLH itself, which probably encompasses multiple disorders, with a variety of etiologies and triggers, and a spectrum of severity. There is no question, however, that these results can help clinicians having to make weighty decisions and, with validation, can be considered by consensus groups for inclusion in diagnostic criteria for HLH.Article page 984▶ Hemophagocytic lymphohistiocytosis (HLH) is both under-recognized and over-diagnosed currently. Despite the use of the revised criteria for diagnosis, established by the Histiocyte Society in 2004, it seems that patients with severe infections, as well as patients with severe underlying rheumatologic and oncologic conditions receiving modern therapies (in whom HLH, or macrophage activation syndrome, can indeed occur), can meet criteria without a convincing “fit” for the clinician (Pediatr Blood Cancer 2007;48:124-31). On the other hand, especially early in the course in previously healthy younger children, HLH sometimes seems to be the “best diagnosis” even though laboratory criteria are not met fully. Accuracy of diagnosis is critical because therapy for HLH is either extremely helpful in abrogating an abnormal inflammatory response if the diagnosis is correct, or extremely harmful in impeding an appropriate response if the diagnosis is incorrect, especially when infection is the sole or predominant pathology. In a particularly robust study, Xu et al evaluated 756 consecutive patients with fever hospitalized in the Hematology/Oncology Unit of the Children's Hospital of Zhejiang University School of Medicine between 2005 and 2010, categorized the etiologies of fever, and also studied three control groups of 202 patients with hematology/oncology conditions without fever, 100 healthy children, and 85 previously healthy children with confirmed bacterial sepsis. Multiplex Th1/Th2 cytokine kit assay was used to measure serum concentrations of defined interleukins (IL), tumor necrosis factors, and interferon. The 71 episodes of HLH showed a highly discriminating cytokine pattern of uniquely highly elevated IFN-γ level (94% sensitivity and 97% specificity for HLH using a cutoff point of 100 pg/mL) and IL-10 level, but only modestly elevated IL-6 level. Combined use of IFN-γ level >75 pg/mL plus IL-10 >60 pg/mL had sensitivity of 93% and specificity of 99% for HLH. The authors point out limitations of the study, as well as the heterogeneity of HLH itself, which probably encompasses multiple disorders, with a variety of etiologies and triggers, and a spectrum of severity. There is no question, however, that these results can help clinicians having to make weighty decisions and, with validation, can be considered by consensus groups for inclusion in diagnostic criteria for HLH. Article page 984▶ Diagnostic Accuracy of a Specific Cytokine Pattern in Hemophagocytic Lymphohistiocytosis in ChildrenThe Journal of PediatricsVol. 160Issue 6PreviewThe study goal was to determine the diagnostic accuracy of a specific cytokine pattern including interferon-gamma (IFN-γ), interleukin (IL)-10, and IL-6 for hemophagocytic lymphohistiocytosis (HLH) in febrile children. Full-Text PDF

Diagnostic Accuracy of a Specific Cytokine Pattern in Hemophagocytic Lymphohistiocytosis in Children

The study goal was to determine the diagnostic accuracy of a specific cytokine pattern including interferon-gamma (IFN-γ), interleukin (IL)-10, and IL-6 for hemophagocytic lymphohistiocytosis (HLH) in febrile children. In this prospective study, 756 patients with fever admitted to a hematology-oncology unit were enrolled. The causes of fever were documented and the serum cytokines, including IFN-γ, tumor necrosis factor-alpha (TNF-α), IL-10, IL-6, IL-4, and IL-2, were determined using cytometric bead array techniques. Of 1474 episodes of fever that were analyzed, 71 episodes of HLH manifested a specific cytokine pattern of highly increased levels of IFN-γ (median level: 1088.5 pg/mL) and IL-10 (623.5 pg/mL) but a moderately increased level of IL-6 (51.1 pg/mL). IL-6 was predominantly increased to varied extents in patients in the sepsis group (244.6 pg/mL) and the nonsepsis infection group (34.7 pg/mL). The diagnostic accuracy of IFN-γ and IL-10 for HLH was 99.5% and 92.8%, respectively. By applying the cutoff point of 100 pg/mL, IFN-γ had a sensitivity of 94.4% and a specificity of 97.2% for HLH. When using the criteria of IFN-γ >75 pg/mL and IL-10 >60 pg/mL, the specificity reached 98.9% and the sensitivity was 93.0%. The specific cytokine pattern of markedly elevated levels of IFN-γ and IL-10 with only modestly elevated IL-6 levels has high diagnostic accuracy for HLH and may be a useful approach to differentiate HLH from infection.

X-Linked Lymphoproliferative Syndrome and Common Variable Immunodeficiency May Not Be Differentiated bySH2D1AandXIAP/BIRC4Genes Sequence Analysis

The X-linked lymphoproliferative syndrome (XLP) is a rare, inherited immunodeficiency characterized by recurrent episodes of hemophagocytic lymphohistiocytosis, hypogammaglobulinemia, and/or lymphomas. Recently, X-linked inhibitor of apoptosis (XIAP/BIRC4) gene defects, in families with XLP but without SH2D1A gene defects, has been defined. The distinction from primary immunodeficiencies with a defined genetic cause is mandatory. A six-year-old male patient was admitted with the complaints of persistent general lymphadenopathy, for two years had fever, bilateral cervical multiple microlymphadenopathy, hepatic/splenic enlargement with laboratory findings as decreased serum immunoglobulins, negative EBV VCA IgM (viral capsid antigen) and anti-EBV EA (antibody to early D antigen), positive EBV VCA IgG (viral capsid antigen) and EBV EBNA (antibody to nuclear antigen). SH2D1A gene analysis was negative. XIAP/BIRC4 sequencing revealed two novel single nucleotide variants (exon 7, 1978G > A, and 1996T > A) in the 3′UTR of the gene in both patient and mother which were not disease causing. XIAP protein expression was found to be normal. The clinical and laboratory resemblance, no gene mutations, and normal XIAP protein expression led us to think that there may be another responsible gene for XLP. The patient will to be followed up as CVID until he presents new diagnostic signs or until the identification of a new gene.

Pediatric acute lymphoblastic leukemia complicated by secondary hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) may be familial or secondary to infections, malignancies, metabolic disorders. Infectious causes are mostly viral and EBV is the mostly frequently seen etiologic agent. In this case, we report a child with acute lymphoblastic leukemia (ALL), who had three episodes of secondary HLH, possibly due to two different viral etiologies, namely CMV and RSV together with her malignancy, during her induction-consolidation treatment.

Perforin gene mutations in adult-onset hemophagocytic lymphohistiocytosis

Perforin gene (PRF1) mutations cause the primary form of hemophagocytic lymphohistiocytosis (HLH). We report a genetic defect of PRF1 in a 62-year-old Japanese man with recurrent episodes of HLH. Sequencing of PRF1 from both peripheral blood mononuclear cells and nail clippings showed compound heterozygous mutation, including deletion of two base pairs at codons 1090 and 1091 (1090-1091delCT) and guanine-to-adenine conversion at nucleotide position 916 (916GAEA). Although primary HLH has been detected in infants and children, genetic mutation of PRF1 or other genes should be considered a differential diagnosis of HLH even in the elderly.