Congenital and Acquired Neutropenia

Chronic neutropenia in childhood: experience of a tertiary center

OBJECTIVE

To assess the prevalence of chronic neutropenia (CN) and the clinical profile of patients with CN aged up to 18 years, followed in the pediatric hematology, rheumatology, or immunology outpatient clinic of a tertiary medical center from May 1, 2018, to 30 April 2019.

METHODS

Retrospective observational study carried out by collecting data from the patient's medical charts. CN was defined as absolute neutrophil count (ANC) below 1.5 × 109/L lasting over three months. Autoimmune neutropenia (AIN) was defined by clinical criteria and an over twofold increase in ANC after glucocorticoid stimulation. AIN was considered secondary when associated with autoimmune or immunoregulatory disorders. Wilcoxon and Fisher's exact tests were used to compare variables; the significance level was 5 %.

RESULTS

A total of 1,039 patients were evaluated; 217 (20 %) presented CN. Twenty-one (2 %) had AIN, classified as primary in 57 % of the cases. The average age at the onset of symptoms was 38.6 months. During follow-up, patients had 4.2 infections on average; frequency was higher among patients with secondary AIN (p = 003). Isolated neutropenia occurred in 43 % of the patients with AIN. Neutropenia resolved in eight (38 %) of the 21 patients with AIN within 19.6 months on average. Eight patients with secondary AIN met the criteria for Inborn Errors of Immunity.

CONCLUSION

AIN prevalence was 2 %. Most cases were first evaluated by a pediatric immunologist or rheumatologist rather than a pediatric hematologist. This study highlights the need for a multidisciplinary approach involving a pediatric immunologist, rheumatologist, and hematologist.

Screening for ELANE, HAX1 and GFI1 gene mutations in children with neutropenia and clinical characterization of two novel mutations in ELANE gene

BACKGROUND

Congenital neutropenia is a rare disease. Recurrent infections since young age are the presentation. The most common mutation causing severe congenital neutropenia (SCN) and cyclic neutropenia (CyN) is the ELANE gene. The objectives of this study were to screen the three common genetic mutations of ELANE, HAX1 and GFI1 in children with chronic neutropenia and to describe the clinical characteristics of children who had the mutations.

METHODS

Infants having ANC < 1,000/cu mm or children aged > 1 year having ANC < 1,500/cu mm at least 3 times in 3 months were enrolled in the study. Patients who had acquired neutropenia due to infection, immune deficiency, or drugs were excluded. The ELANE gene was first studied; and if mutations were not identified, the HAX1 and GFI1 genes were further examined.

RESULTS

A total of 60 patients were enrolled in the study. The median (range) age, ratio of female to male, ANC, and last follow-up age were 9.2 (0.5-45.2) months, 1:1.2, 248 (0-1,101) /cu mm, and 19.9 (3.5-202.3) months, respectively. Infections were noted in 67.3% of all patients. ELANE gene mutation was found in only four patients (6.7%), and the rest (56 patients) showed no mutations in the HAX1 and GFI1 genes. In patients without mutations, 66.0% had normal ANC during the follow-up, with a median (range) age for normal ANC of 19.8 (4.0-60.0) months. Two novel mutations p. Ala79del (c.234_236del) and p. Val197GlufsTer18 (c.589_590insAGGCCGGC) were identified, and they respectively cause SCN and CyN. Patients with the two novel mutations presented with several episodes of infection, including pneumonia, sepsis, abscess, otitis media, and gum infection.

CONCLUSION

The genetic screening for ELANE, HAX1, and GFI1 gene mutations in 60 patients with chronic neutropenia could identify four patients (6.7%) with ELANE gene mutation and two novel mutations, p. Ala79del in exon 3 and p. Val197GlufsTer18 in exon 4 causing SCN; and CyN, respectively.

Diagnosis and management of neutropenia in children: The approach of the Study Group on Neutropenia and Marrow Failure Syndromes of the Pediatric Italian Hemato-Oncology Association (Associazione Italiana Emato-Oncologia Pediatrica - AIEOP)

Neutropenia refers to a group of diseases characterized by a reduction in neutrophil levels below the recommended age threshold. The present study aimed to review the diagnosis and management of neutropenia, including a diagnostic toolkit and candidate underlying genes. This study also aimed to review the progress toward the definition of autoimmune and idiopathic neutropenia rising in infancy or in late childhood but without remission, and provide suggestions for efficient diagnostics, including indications for the bone marrow and genetic testing. The management and treatment protocols for common and unique presentations are also reviewed, providing evidence tailored to a single patient.

Dysfunction of immune system in the development of large granular lymphocyte leukemia

OBJECTIVES

Large granular lymphocyte (LGL) leukemia is a rare type of lymphoproliferative disease caused by clonal antigenic stimulation of T cells and natural killer (NK) cells.

METHODS

In this review, we focus on the current knowledge of the immunological dysfunctions associated with LGL leukemia and the associated disorders coexistent with this disease. Novel therapeutic options targeting known molecular mechanisms are also discussed.

RESULTS AND DISCUSSION

The pathogenesis of LGL leukemia involves the accumulation of gene mutations, dysregulated signaling pathways and immunological dysfunction. Mounting evidence indicated that dysregulated survival signaling pathways may be responsible for the immunological dysfunction in LGL leukemia including decreased numbers of neutrophils, dysregulated signal transduction of NK cells, abnormal B-cells, aberrant CD8+ T cells, as well as autoimmune and hematological abnormalities.

CONCLUSION

A better understanding of the immune dysregulation triggered by LGL leukemia will be beneficial to explore the pathogenesis and potential therapeutic targets for this disease.

Patients immunodéprimés, quel pathogène pour quel déficit immunitaire ? (en dehors de l’infection à VIH)

Le nombre de patients immunodéprimés ne cesse d’augmenter en raison de l’amélioration du pronostic global du cancer et de l’utilisation croissante d’immunosuppresseurs tant en transplantation qu’au cours des maladies auto-immunes. Les infections sévères restent la première cause d’admission en réanimation dans cette population et sont dominées par les atteintes respiratoires. On distingue les déficits primitifs, volontiers révélés dans l’enfance, des déficits secondaires (médicamenteux ou non), les plus fréquents. Dans tous les cas, les sujets sont exposés à des infections inhabituelles de par leur fréquence, leur type et leur sévérité. À côté des pyogènes habituels, les infections opportunistes et la réactivation d’infections latentes font toute la complexité de la démarche diagnostique. Celle-ci doit être rigoureuse, orientée par le type de déficit, les antécédents, les prophylaxies éventuelles et la présentation clinicoradiologique. Elle permettra seule de guider le traitement probabiliste et les examens étiologiques, l’absence de diagnostic étant associée à une mortalité élevée.

Quantitative Simulations Predict Treatment Strategies Against Fungal Infections in Virtual Neutropenic Patients

The condition of neutropenia, i.e., a reduced absolute neutrophil count in blood, constitutes a major risk factor for severe infections in the affected patients. Candida albicans and Candida glabrata are opportunistic pathogens and the most prevalent fungal species in the human microbiota. In immunocompromised patients, they can become pathogenic and cause infections with high mortality rates. In this study, we use a previously established approach that combines experiments and computational models to investigate the innate immune response during blood stream infections with the two fungal pathogens C. albicans and C. glabrata. First, we determine immune-reaction rates and migration parameters under healthy conditions. Based on these findings, we simulate virtual patients and investigate the impact of neutropenic conditions on the infection outcome with the respective pathogen. Furthermore, we perform in silico treatments of these virtual patients by simulating a medical treatment that enhances neutrophil activity in terms of phagocytosis and migration. We quantify the infection outcome by comparing the response to the two fungal pathogens relative to non-neutropenic individuals. The analysis reveals that these fungal infections in neutropenic patients can be successfully cleared by cytokine treatment of the remaining neutrophils; and that this treatment is more effective for C. glabrata than for C. albicans.

Approach to the patient with neutropenia in childhood

Neutrophils have an important role in host defense and acute inflammation. It is well known that susceptibility to infection increases when the neutrophil count is low. Neutropenia were classified as mild, moderate and severe according to the neutrophil counts, or acute and chronic depending on the duration of neutropenia, or congenital and acquired according to the mechanism. The patients with neutropenia are clinically different due to underlying mechanism, they have life- threatening infections or no infection may be observed. The most common cause of acquired neutropenia is viral infection, followed by drugs and autoimmune neutropenia. Congenital neutropenia are usually diagnosed by acute and life- threatening invasive bacterial and fungal infections. Immune system disorders and other systemic abnormalities may be accompanied or not. Recent years, novel single gen defects causing congenital neutropenia were defined through advanced genetic techniques. Molecular diagnosis is useful for risk stratification, choice of therapy and prognosis on follow- up. This review was prepared for pediatricians as a guide focused on approach neutropenia, which tests should be performed and when should be referred to a specialist.

Pathogenesis of ELANE-mutant severe neutropenia revealed by induced pluripotent stem cells

Severe congenital neutropenia (SCN) is often associated with inherited heterozygous point mutations in ELANE, which encodes neutrophil elastase (NE). However, a lack of appropriate models to recapitulate SCN has substantially hampered the understanding of the genetic etiology and pathobiology of this disease. To this end, we generated both normal and SCN patient-derived induced pluripotent stem cells (iPSCs), and performed genome editing and differentiation protocols that recapitulate the major features of granulopoiesis. Pathogenesis of ELANE point mutations was the result of promyelocyte death and differentiation arrest, and was associated with NE mislocalization and activation of the unfolded protein response/ER stress (UPR/ER stress). Similarly, high-dose G-CSF (or downstream signaling through AKT/BCL2) rescues the dysgranulopoietic defect in SCN patient-derived iPSCs through C/EBPβ-dependent emergency granulopoiesis. In contrast, sivelestat, an NE-specific small-molecule inhibitor, corrected dysgranulopoiesis by restoring normal intracellular NE localization in primary granules; ameliorating UPR/ER stress; increasing expression of CEBPA, but not CEBPB; and promoting promyelocyte survival and differentiation. Together, these data suggest that SCN disease pathogenesis includes NE mislocalization, which in turn triggers dysfunctional survival signaling and UPR/ER stress. This paradigm has the potential to be clinically exploited to achieve therapeutic responses using lower doses of G-CSF combined with targeting to correct NE mislocalization.

[Pediatric perioperative systemic pain therapy: Austrian interdisciplinary recommendations on pediatric perioperative pain management]

BACKGROUND

Many analgesics used in adult medicine are not licensed for pediatric use. Licensing limitations do not, however, justify that children are deprived of a sufficient pain therapy particularly in perioperative pain therapy. The treatment is principally oriented to the strength of the pain. Due to the degree of pain caused, intramuscular and subcutaneous injections should be avoided generally.

NON-OPIOIDS

The basis of systemic pain therapy for children are non-opioids and primarily non-steroidal anti-inflammatory drugs (NSAIDs). They should be used prophylactically. The NSAIDs are clearly more effective than paracetamol for acute posttraumatic and postoperative pain and additionally allow economization of opioids. Severe side effects are rare in children but administration should be carefully considered especially in cases of hepatic and renal dysfunction or coagulation disorders. Paracetamol should only be taken in pregnancy and by children when there are appropriate indications because a possible causal connection with bronchial asthma exists. To ensure a safe dosing the age, body weight, duration of therapy, maximum daily dose and dosing intervals must be taken into account. Dipyrone is used in children for treatment of visceral pain and cholic. According to the current state of knowledge the rare but severe side effect of agranulocytosis does not justify a general rejection for short-term perioperative administration.

OPIOIDS

In cases of insufficient analgesia with non-opioid analgesics, the complementary use of opioids is also appropriate for children of all age groups. They are the medication of choice for episodes of medium to strong pain and are administered in a titrated form oriented to effectiveness. If severe pain is expected to last for more than 24 h, patient-controlled anesthesia should be implemented but requires a comprehensive surveillance by nursing personnel.

KETAMINE

Ketamine is used as an adjuvant in postoperative pain therapy and is recommended for use in pediatric sedation and analgosedation.

Nonchemotherapy drug-induced neutropenia and agranulocytosis: could medications be the culprit?

Drug-induced agranulocytosis is a severe complication that has been implicated with most classes of medications. Medications such as clozapine, trimethoprim-sulfamethoxazole and methimazole have been more commonly associated with agranulocytosis than other agents. Although the pathogenesis isn't fully elucidated, it appears to be two-fold with a direct toxicity to the myeloid cell line and immune-mediated destruction. Patients may be asymptomatic at the time neutropenia is discovered or may present with more severe complications such as sepsis. In approximately 5% of cases drug-induced agranulocytosis may be fatal. Management of drug-induced agranulocytosis includes the immediate discontinuation of the offending medication, initiation of broad-spectrum antibiotics and consideration of the use of granulocyte colony-stimulating factors in high-risk patients.

Adverse reactions to targeted and non-targeted chemotherapeutic drugs with emphasis on hypersensitivity responses and the invasive metastatic switch

More than 100 drugs are used to treat the many different cancers. They can be divided into agents with relatively broad, non-targeted specificity and targeted drugs developed on the basis of a more refined understanding of individual cancers and directed at specific molecular targets on different cancer cells. Individual drugs in both groups have been classified on the basis of their mechanism of action in killing cancer cells. The targeted drugs include proteasome inhibitors, toxic chimeric proteins and signal transduction inhibitors such as tyrosine kinase (non-receptor and receptor), serine/threonine kinase, histone deacetylase and mammalian target of rapamycin inhibitors. Increasingly used targeted vascular (VEGF) and platelet-derived endothelial growth factor blockade can provoke a range of pathological consequences. Many of the non-targeted drugs are cytotoxic, suppressing haematopoiesis as well as provoking cutaneous eruptions and vascular, lung and liver injury. Cytotoxic side effects of the targeted drugs occur less often and usually with less severity, but they show their own unusual adverse effects including, for example, a lengthened QT interval, a characteristic papulopustular rash, nail disorders and a hand-foot skin reaction variant. The term hypersensitivity is widely used across a number of disciplines but not always with the same definition in mind, and the terminology needs to be standardised. This is particularly apparent in cancer chemotherapy where anti-neoplastic drug-induced thrombocytopenia, neutropenia, anaemia, vascular disorders, liver injury and lung disease as well as many dermatological manifestations sometimes have an immune basis. The most insidious of all adverse consequences of targeted therapies, however, are tumour adaptation, increased malignancy and the invasive metastatic switch seen with anti-angiogenic drugs that inhibit the VEGF-A pathway. Adverse reactions to 44 non-targeted and 33 targeted, frequently used, chemotherapeutic drugs are presented together with discussions of diagnosis, premedications, desensitizations and importance of understanding the mechanisms underlying the various drug-induced reactions. There is need for wide-ranging acceptance of what constitutes a hypersensitivity reaction and for allergists to be more involved in the diagnosis, treatment and prevention of chemotherapeutic drug-induced hypersensitivity reactions.

Adverse events to monoclonal antibodies used for cancer therapy: Focus on hypersensitivity responses

Fifteen monoclonal antibodies (mAbs) are currently registered and approved for the treatment of a range of different cancers. These mAbs are specific for a limited number of targets (9 in all). Four of these molecules are indeed directed against the B-lymphocyte antigen CD20; 3 against human epidermal growth factor receptor 2 (HER2 or ErbB2), 2 against the epidermal growth factor receptor (EGFR), and 1 each against epithelial cell adhesion molecule (EpCAM), CD30, CD52, vascular endothelial growth factor (VEGF), tumor necrosis factor (ligand) superfamily, member 11 (TNFSF11, best known as RANKL), and cytotoxic T lymphocyte-associated protein 4 (CTLA4). Collectively, the mAbs provoke a wide variety of systemic and cutaneous adverse events including the full range of true hypersensitivities: Type I immediate reactions (anaphylaxis, urticaria); Type II reactions (immune thrombocytopenia, neutopenia, hemolytic anemia); Type III responses (vasculitis, serum sickness; some pulmonary adverse events); and Type IV delayed mucocutaneous reactions as well as infusion reactions/cytokine release syndrome (IRs/CRS), tumor lysis syndrome (TLS), progressive multifocal leukoencephalopathy (PML) and cardiac events. Although the term "hypersensitivity" is widely used, no common definition has been adopted within and between disciplines and the requirement of an immunological basis for a true hypersensitivity reaction is sometimes overlooked. Consequently, some drug-induced adverse events are sometimes incorrectly described as "hypersensitivities" while others that should be described are not.

Fibrosis and subsequent cytopenias are associated with basic fibroblast growth factor-deficient pluripotent mesenchymal stromal cells in large granular lymphocyte leukemia

Cytopenias occur frequently in systemic lupus erythematosus, rheumatoid arthritis, Felty's syndrome, and large granular lymphocyte (LGL) leukemia, but the bone marrow microenvironment has not been systematically studied. In LGL leukemia (n = 24), retrospective analysis of bone marrow (BM) histopathology revealed severe fibrosis in 15 of 24 patients (63%) in association with the presence of cytopenias, occurrence of autoimmune diseases, and splenomegaly, but was undetectable in control cases with B cell malignancies (n = 11). Fibrosis severity correlated with T cell LGL cell numbers in the BM, but not in the periphery, suggesting deregulation is limited to the BM microenvironment. To identify fibrosis-initiating populations, primary mesenchymal stromal cultures (MSCs) from patients were characterized and found to display proliferation kinetics and overabundant collagen deposition, but displayed normal telomere lengths and osteoblastogenic, chondrogenic, and adipogenic differentiation potentials. To determine the effect of fibrosis on healthy hematopoietic progenitor cells (HPCs), bioartificial matrixes from rat tail or purified human collagen were found to suppress HPC differentiation and proliferation. The ability of patient MSCs to support healthy HSC proliferation was significantly impaired, but could be rescued with collagenase pretreatment. Clustering analysis confirmed the undifferentiated state of patient MSCs, and pathway analysis revealed an inverse relationship between cell division and profibrotic ontologies associated with reduced basic fibroblast growth factor production, which was confirmed by ELISA. Reconstitution with exogenous basic fibroblast growth factor normalized patient MSC proliferation, collagen deposition, and HPC supportive function, suggesting LGL BM infiltration and secondary accumulation of MSC-derived collagen is responsible for hematopoietic failure in autoimmune-associated cytopenias in LGL leukemia.

T-large granular lymphocyte leukemia: current molecular concepts

T-large granular lymphocyte (T-LGL) leukemia is a chronic and often indolent T cell lymphoproliferation characterized by extreme expansion of a semi-autonomous cytotoxic T lymphocyte (CTL) clone. Clinically, T-LGL can be associated with various cytopenias; neutropenia constitutes the most frequent manifestation. LGL clone represents a pathologic counterpart of the cytotoxic effector T cell but an abnormal memory CD8 cell seems to provide the supply of the matured LGL population. Analysis of clonal T cell receptor (TCR) rearrangement and complementarity determining region 3 (CDR3) of the TCR beta-chain is a useful tool to investigate clonal expansions, track the frequency of expanded clones and also clinically useful to monitor the response to therapy. The lessons learned from molecular analysis of clonal repertoire support a clinically-derived conclusion that the LGL clone arises in the context of an initially polyclonal immune response or an autoimmune process. Consequently, specific manifestations of T-LGL may be a result of the recognition spectrum of the transformed clone and the cytokines it produces. Due to the often monoclonal manifestation, T-LGL constitutes a suitable model to investigate polyclonal CTL-mediated processes. Application of new technologies, including TCR repertoire analysis by sequencing, clonotypic quantitative PCR and VB flow cytometry facilitate clinical diagnosis and may allow insights into the regulation of TCR repertoire and consequences resulting from the contraction of clonal diversity.

Relapsing-remitting multiple sclerosis and chronic idiopathic neutropenia: a challenging combination

We report the challenges of treating relapsing-remitting multiple sclerosis (MS) in a 31-year-old woman with long-standing chronic idiopathic neutropenia. The treatment with the disease-modifying therapy interferon-β was significantly complicated by a further fall in her generally low neutrophil count, to values below 0.5×10(9)/l, although this recovered rapidly when the treatment was stopped. We discuss the difficulties of balancing the risk of neutropenia with a risk of MS relapse.

Pathogenesis and prognosis of neutropenia in infants and children admitted in a university children hospital in Egypt

This study aimed to assess the prevalence, severity, and etiology of neutropenia in infants and children admitted to a children's hospital in Egypt. A total of 200 patients with neutropenia were recruited from April 1, 2010 to September 30, 2010. Patients with a known hematological or immunological disease were excluded. Patients were followed till recovery or an underlying cause was uncovered. Viral serological analysis was done for patients with moderate/severe neutropenia, including cytomegalovirus (CMV); Epstein-Barr virus (EBV); hepatitis A, B, and C viruses; and HIV. Antineutrophil cytoplasmic antibody (ANCA) tested by enzyme immunoassay and bone marrow aspirate were done for prolonged neutropenia. The results revealed that neutropenia was mild in 90 (45%), moderate in 56 (28%), and severe in 54 (27%). Clinical diagnosis at admission was bronchopneumonia (38%), pyrexia of undetermined etiology (17%), bronchiolitis (13%), urinary tract infection (9%), acute gastroenteritis (8%), hepatitis (6.5%), and septicemia (5%). Patients with mild neutropenia recovered within 1 week. Among 110 patients with moderate/severe neutropenia, 80 (73%) recovered in <3 weeks. Predictors of prolonged neutropenia were age younger than 18 months (P < .01), absolute neutrophils count (ANC) < 500/mm(3) (P < .05), hemoglobin < 10 gm/dL (P < .05), and positive CMV serology (P < .01). CMV and EBV serology were positive in 34.5% and 7.3% of patients, respectively. ANCA was positive in 42.8% of patients with prolonged severe neutropenia. In conclusion, neutropenia is a frequent finding in Egyptian infants and children, usually mild and transient, and mainly associated with infection. CMV and EBV are associated with prolonged neutropenia. Immune neutropenia is a common cause of moderate/severe neutropenia in the first two years of life.

Why is my patient neutropenic?

Neutropenia is a common reason for hematology consultations in the inpatient and outpatient settings and is defined as an absolute neutrophil count less than 1500 cells/μL. Neutropenia varies in severity, with more profound neutropenia being associated with higher rates of infections and infection-related deaths. The causes for neutropenia are diverse and include congenital and acquired conditions (ie, autoimmune, drugs, infection, and malignancy). This article outlines the most common causes of neutropenia and discusses differential diagnoses, treatment modalities, and the mechanisms by which neutropenia occurs.

Congenital and acquired neutropenias consensus guidelines on therapy and follow-up in childhood from the Neutropenia Committee of the Marrow Failure Syndrome Group of the AIEOP (Associazione Italiana Emato-Oncologia Pediatrica)

The management of congenital and acquired neutropenias presents some differences according to the type of the disease. Treatment with recombinant human granulocyte-colony stimulating factor (G-CSF) is not standardized and scanty data are available on the best schedule to apply. The frequency and the type of longitudinal controls in patients affected with neutropenias are not usually discussed in the literature. The Neutropenia Committee of the Marrow Failure Syndrome Group (MFSG) of the Associazione Italiana di Emato-Oncologia Pediatrica (AIEOP) elaborated this document following design and methodology formerly approved by the AIEOP board. The panel of experts reviewed the literature on the topic and participated in a conference producing a document that includes recommendations on neutropenia treatment and timing of follow-up.

Congenital and acquired neutropenia consensus guidelines on diagnosis from the Neutropenia Committee of the Marrow Failure Syndrome Group of the AIEOP (Associazione Italiana Emato-Oncologia Pediatrica)

Congenital and acquired neutropenia are rare disorders whose frequency in pediatric age may be underestimated due to remarkable differences in definition or misdiagnosed because of the lack of common practice guidelines. Neutropenia Committee of the Marrow Failure Syndrome Group (MFSG) of the AIEOP (Associazione Italiana Emato-Oncologia Pediatrica) elaborated this document following design and methodology formerly approved by the AIEOP board. The panel of experts reviewed the literature on the topic and participated in a conference producing a document which includes a classification of neutropenia and a comprehensive guideline on diagnosis of neutropenia.

The spectrum of large granular lymphocyte leukemia and Felty's syndrome

PURPOSE OF REVIEW

Patients with chronic large granular lymphocyte (LGL) leukemia often have rheumatoid arthritis (RA), neutropenia and splenomegaly, thereby resembling the manifestations observed in patients with Felty's syndrome, which is a rare complication of RA characterized by neutropenia and splenomegaly. Both entities have similar clinical and laboratory presentation, as well as a common genetic determinant, HLA-DR4, indicating they may be part of the same disease spectrum. This review paper seeks to discuss the underlying pathogenesis and therapeutic algorithm of RA, neutropenia and splenomegaly in the spectrum of LGL leukemia and Felty's syndrome.

RECENT FINDINGS

We hypothesize that there may be a common pathogenic mechanism between LGL leukemia and typical Felty's syndrome. Phenotypic and functional data have strongly suggested that CD3 LGL leukemia is antigen-activated. Aberrations in the T-cell repertoire with the emergence of oligoclonal/clonal lymphoid populations have been found to play a pivotal role in pathogenesis of RA. The biologic properties of the pivotal T cell involved in RA pathogenesis are remarkably similar to those in leukemic LGL.

SUMMARY

RA-associated T-cell LGL leukemia and articular manifestations of typical Felty's syndrome are not distinguishable. A common pathogenetic link between LGL leukemia and RA is proposed.

Neutrophil elastase, proteinase 3, and cathepsin G as therapeutic targets in human diseases

Polymorphonuclear neutrophils are the first cells recruited to inflammatory sites and form the earliest line of defense against invading microorganisms. Neutrophil elastase, proteinase 3, and cathepsin G are three hematopoietic serine proteases stored in large quantities in neutrophil cytoplasmic azurophilic granules. They act in combination with reactive oxygen species to help degrade engulfed microorganisms inside phagolysosomes. These proteases are also externalized in an active form during neutrophil activation at inflammatory sites, thus contributing to the regulation of inflammatory and immune responses. As multifunctional proteases, they also play a regulatory role in noninfectious inflammatory diseases. Mutations in the ELA2/ELANE gene, encoding neutrophil elastase, are the cause of human congenital neutropenia. Neutrophil membrane-bound proteinase 3 serves as an autoantigen in Wegener granulomatosis, a systemic autoimmune vasculitis. All three proteases are affected by mutations of the gene (CTSC) encoding dipeptidyl peptidase I, a protease required for activation of their proform before storage in cytoplasmic granules. Mutations of CTSC cause Papillon-Lefèvre syndrome. Because of their roles in host defense and disease, elastase, proteinase 3, and cathepsin G are of interest as potential therapeutic targets. In this review, we describe the physicochemical functions of these proteases, toward a goal of better delineating their role in human diseases and identifying new therapeutic strategies based on the modulation of their bioavailability and activity. We also describe how nonhuman primate experimental models could assist with testing the efficacy of proposed therapeutic strategies.

Oral manifestations of hematologic and nutritional diseases

Oral manifestations of hematologic and nutritional deficiencies can affect the mucous membranes, teeth, periodontal tissues, salivary glands, and perioral skin. This article reviews common oral manifestations of hematologic conditions starting with disorders of the white blood cells including cyclic hematopoiesis (cyclic neutropenia), leukemias, lymphomas, plasma cell dyscrasias, and mast cell disorders; this is followed by a discussion of the impact of red blood cell disorders including anemias and less common red blood cell dyscrasias (sickle cell disease, hemochromatosis, and congenital erythropoietic porphyria) as well as thrombocytopenia. Several nutritional deficiencies exhibit oral manifestations. The authors specifically discuss the impact of water-soluble vitamins (B2, B3, B6, B9, B12, and C), fat-soluble vitamins (A, D, and K) and the eating disorders anorexia nervosa and bulimia nervosa on the oral mucosa.

The root of many evils: indolent large granular lymphocyte leukaemia and associated disorders

Large granular lymphocytes (LGL) leukaemia can arise from either natural killer (NK) cells or cytotoxic T lymphocytes (CTL). The T-cell form of LGL leukaemia has significant overlap with other haematological disorders and autoimmune diseases. Here we provide an overview of LGL biology. We also focus discussion on the indolent LGL leukaemia related disorders and their causal relationships. We then discuss the potential relationships and distinctions between indolent LGL leukaemia and non-malignant clonal lymphocyte expansion that occur in otherwise healthy individuals, especially elder people.

Large granular lymphocyte leukemia

Clonal diseases of large granular lymphocytes (LGLs) represent a spectrum of clinically rare lymphoproliferative malignancies arising from either mature T-cell (CD3(+)) or natural killer (NK)-cell (CD3(-)) lineages. The clinical behavior of these disorders ranges from indolent to very aggressive. Patients with symptomatic indolent T-cell or NK-cell LGL leukemia are usually treated with immunosuppressive therapies; in contrast, aggressive T-cell or NK-cell LGL leukemias require intensive chemotherapy regimens. Novel targeted therapies are currently being tested in clinical studies.

Clonal predominance of CD8(+) T cells in patients with unexplained neutropenia

OBJECTIVE

T-cell-mediated autoimmunity may be involved in some cases of idiopathic neutropenia. We hypothesized that a precise T-cell receptor repertoire analysis may uncover cytotoxic T-cell (CTL) expansions that are less pronounced than those seen in T large granular lymphocyte leukemia (T-LGL), but are pathophysiologically analogous and thus can serve as markers of a T-cell-mediated process.

MATERIALS AND METHODS

Using rational algorithms for T-cell receptor analysis and in vivo tracking of CTL responses previously established in our laboratory, we studied patients with unexplained chronic neutropenia (n = 20), T-LGL (n = 15), and healthy controls (n = 12). We further investigated the involvement of soluble inhibitory factors by coculture assays. To determine the level of immune activation, we studied interferon-gamma expression in CD8(+)cells using Taqman polymerase chain reaction.

RESULTS

Fifteen expanded (immunodominant) CTL clones were detected in 12 of 20 patients. In comparison to LGL leukemia, these clones were less immunodominant, but clearly discernible from subclinical lymphoproliferations in controls. As a surrogate of cytotoxic activity, we found markedly increased production of interferon-gamma in most of the neutropenia patients, irrespective of the presence of immunodominant CTL clones.

CONCLUSIONS

These results suggest that, while immunodominant CTL clones are detectable in a proportion of patients only, CTL-mediated pathophysiology may be a general mechanism operating in idiopathic neutropenia. Oligogoclonal CTL expansions in chronic neutropenia may indicate an ongoing autoimmune process, while highly polarized monoclonalities in a subset of neutropenic LGL patients may represent the "extreme" end of the clonal continuum.

Mosaic tetraploidy and transient GFI1 mutation in a patient with severe chronic neutropenia

This report presents the case of a 15-year-old male with severe chronic neutropenia, leukopenia, and persistent tetraploid mosaicism in the bone marrow and peripheral blood. His father had mild neutropenia and bone marrow tetraploidy. Flow cytometric analysis of DNA content peripheral blood showed tetraploidy in 20% of granulocytes and 15% of monocytes. Sequence analysis of the ELA2 gene was normal, but the GFI1 gene exhibited transient appearance of single base changes the coding region and promoter. We speculate that an underlying genetic defect, inherited in an autosomal dominant pattern, leads to both disordered mitosis and neutropenia in this kindred.

Haematological toxicity of drugs used in psychiatry

Almost all classes of psychotropic agents have been reported to cause blood dyscrasias. Mechanisms include direct toxic effects upon the bone marrow, the formation of antibodies against haematopoietic precursors or involve peripheral destruction of cells. Agranulocytosis is probably the most important drug-related blood dyscrasia. The mortality from drug-induced agranulocytosis is 5-10% in Western countries. The manifestations of agranulocytosis are secondary to infection. Aggressive treatment with intravenous broad-spectrum antimicrobials and bone marrow stimulants may be required. Of drugs encountered in psychiatry, antipsychotics including clozapine (risk of agranulocytosis approximately 0.8%, predominantly in the first year of treatment) and phenothiazines (chlorpromazine agranulocytosis risk approximately 0.13%), and antiepileptics (notably carbamazepine, neutropenia risk approximately 0.5%) are the most common causes of drug-related neutropenia/agranulocytosis. Drugs known to cause neutropenia should not be used concomitantly with other drugs known to cause this problem. High temperature and other indicators of possible infection should be looked for routinely during treatment. Clozapine is well known as a drug that can cause blood dyscrasias, but olanzapine and other atypicals may also cause similar problems. In addition to genetic factors, there are likely to be dose-related and immunological components to these phenomena. Important lessons have been learnt from the haematological monitoring that is necessary with clozapine and the monitoring has been very successful in preventing deaths related to clozapine-induced agranulocytosis. Continuing research into the mechanisms of drug-induced neutropenia and agranulocytosis may serve to further enhance the safe use not only of clozapine, but also of other agents.

A molecular classification of congenital neutropenia syndromes

Current knowledge on the molecular pathogenesis of severe congenital neutropenia indicates that the clinical diagnosis includes a heterogeneous group of disorders following different patterns of inheritance. Similarly, multifaceted syndromes associated with neutropenia can be classified molecularly, which in turn allows for a better understanding of the basis of the neutropenia. Many of the neutropenia disorders can be treated with G-CSF (filgrastim) to increase the neutrophil count, thereby reducing infection morbidity and mortality. In some instances hematopoietic stem cell transplantation remains the only curative treatment currently available. This review describes and classifies, on a molecular basis, both primary congenital neutropenia and multifaceted syndromes associated with neutropenia.

The clinical, immunohematological, and molecular study of Iranian patients with severe congenital neutropenia

Severe congenital neutropenia (SCN) is a rareE primary immunodeficiency disorder characterized by early onset recurrent infections in association with persistent severe agranulocytosis. To identify the clinical, immunohematological, and molecular characteristics of patients with SCN, 18 Iranian patients with the mean age of 8.8 +/- 5.8 years were investigated in this study. All of these patients experienced severe neutropenia; the mean of absolute neutrophil count was 281.4 +/- 137.7 cells/mm3. Bone marrow findings were typified by a myeloid maturation arrest at the promyelocyte-myelocyte stage in these patients. Molecular analysis revealed different mutations in the ELA-2 gene of one patient and in the HAX-1 gene of another three patients. The most common presenting complaints in these patients were superficial abscesses, oral ulcers, cutaneous infections, omphalitis, and pneumonia. During the course of illness, all patients developed mucocutaneous manifestations, and 16 cases had respiratory infections. The most commonly manifestations were abscesses, oral ulcers, pneumonia, periodontitis, otitis media, cutaneous infections, mucocutaneous candidiasis, and acute diarrhea. Three patients died because of a severe infection. Although SCN is a rare disorder, early onset of severe and recurrent infections should always raise a suspicion, which deserves further evaluation for detecting such disorder.

Diseases of large granular lymphocytes

BACKGROUND

Clonal diseases of large granular lymphocytes (LGLs) are rare lymphoproliferative malignancies that arise from either mature T-cell (CD3+) or natural killer (NK)-cell (CD3-) lineages. They manifest a distinct biologic behavior that ranges from indolent to very aggressive.

METHODS

We discuss four distinct diseases involving LGLs: indolent T-cell LGL leukemia, aggressive T-cell LGL leukemia, chronic NK-cell leukemia, and aggressive NK-cell leukemia. Furthermore, we present an up-to-date systematic review of therapies for each entity.

RESULTS

Sustained LGLs, characteristic immunophenotype, clonal origin of leukemic cells, and clinical presentation are the most important features that distinguish indolent from aggressive subtypes of LGL leukemia and guide the selection of therapy. Patients with symptomatic indolent T-cell or NK-cell LGL leukemia are usually treated with immunosuppressive therapies in contrast to aggressive T-cell and NK-cell LGL leukemia, which require intensive chemotherapy induction regimens. Novel targeted therapies using monoclonal antibodies against receptors, including CD2, CD52, the beta subunit of the interleukin-2 receptor, and small molecules such as tipifarnib, are undergoing evaluation in clinical trials.

CONCLUSIONS

Future scientific advances focusing on the delineation of molecular pathogenic mechanisms and the development of new targeted therapies for each distinct LGL leukemia entity should lead to improved outcomes of patients with these disorders.

Impaired neutrophil activity and increased susceptibility to bacterial infection in mice lacking glucose-6-phosphatase-beta

Neutropenia and neutrophil dysfunction are common in many diseases, although their etiology is often unclear. Previous views held that there was a single ER enzyme, glucose-6-phosphatase-alpha (G6Pase-alpha), whose activity--limited to the liver, kidney, and intestine--was solely responsible for the final stages of gluconeogenesis and glycogenolysis, in which glucose-6-phosphate (G6P) is hydrolyzed to glucose for release to the blood. Recently, we characterized a second G6Pase activity, that of G6Pase-beta (also known as G6PC), which is also capable of hydrolyzing G6P to glucose but is ubiquitously expressed and not implicated in interprandial blood glucose homeostasis. We now report that the absence of G6Pase-beta led to neutropenia; defects in neutrophil respiratory burst, chemotaxis, and calcium flux; and increased susceptibility to bacterial infection. Consistent with this, G6Pase-beta-deficient (G6pc3-/-) mice with experimental peritonitis exhibited increased expression of the glucose-regulated proteins upregulated during ER stress in their neutrophils and bone marrow, and the G6pc3-/- neutrophils exhibited an enhanced rate of apoptosis. Our results define a molecular pathway to neutropenia and neutrophil dysfunction of previously unknown etiology, providing a potential model for the treatment of these conditions.