'Myelokathexis'. Neutropenia with marrow hyperplasia

Disease Progression of WHIM Syndrome in an International Cohort of 66 Pediatric and Adult Patients

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome (WS) is a combined immunodeficiency caused by gain-of-function mutations in the C-X-C chemokine receptor type 4 (CXCR4) gene. We characterize a unique international cohort of 66 patients, including 57 (86%) cases previously unreported, with variable clinical phenotypes. Of 17 distinct CXCR4 genetic variants within our cohort, 11 were novel pathogenic variants affecting 15 individuals (23%). All variants affect the same CXCR4 region and impair CXCR4 internalization resulting in hyperactive signaling. The median age of diagnosis in our cohort (5.5 years) indicates WHIM syndrome can commonly present in childhood, although some patients are not diagnosed until adulthood. The prevalence and mean age of recognition and/or onset of clinical manifestations within our cohort were infections 88%/1.6 years, neutropenia 98%/3.8 years, lymphopenia 88%/5.0 years, and warts 40%/12.1 years. However, we report greater prevalence and variety of autoimmune complications of WHIM syndrome (21.2%) than reported previously. Patients with versus without family history of WHIM syndrome were diagnosed earlier (22%, average age 1.3 years versus 78%, average age 5 years, respectively). Patients with a family history of WHIM syndrome also received earlier treatment, experienced less hospitalization, and had less end-organ damage. This observation reinforces previous reports that early treatment for WHIM syndrome improves outcomes. Only one patient died; death was attributed to complications of hematopoietic stem cell transplantation. The variable expressivity of WHIM syndrome in pediatric patients delays their diagnosis and therapy. Early-onset bacterial infections with severe neutropenia and/or lymphopenia should prompt genetic testing for WHIM syndrome, even in the absence of warts.

WHIM Syndrome: from Pathogenesis Towards Personalized Medicine and Cure

WHIM syndrome is a rare combined primary immunodeficiency disease named by acronym for the diagnostic tetrad of warts, hypogammaglobulinemia, infections, and myelokathexis. Myelokathexis is a unique form of non-cyclic severe congenital neutropenia caused by accumulation of mature and degenerating neutrophils in the bone marrow; monocytopenia and lymphopenia, especially B lymphopenia, also commonly occur. WHIM syndrome is usually caused by autosomal dominant mutations in the G protein-coupled chemokine receptor CXCR4 that impair desensitization, resulting in enhanced and prolonged G protein- and β-arrestin-dependent responses. Accordingly, CXCR4 antagonists have shown promise as mechanism-based treatments in phase 1 clinical trials. This review is based on analysis of all 105 published cases of WHIM syndrome and covers current concepts, recent advances, unresolved enigmas and controversies, and promising future research directions.

Pathogenesis, diagnosis and therapeutic strategies in WHIM syndrome immunodeficiency

21 INTRODUCTION

WHIM syndrome is a rare combined primary immunodeficiency disorder caused by autosomal dominant gain-of-function mutations in the chemokine receptor CXCR4. It is the only Mendelian condition known to be caused by mutation of a chemokine or chemokine receptor. As such, it provides a scientific opportunity to understand chemokine-dependent immunoregulation in humans and a medical opportunity to develop mechanism-based treatment and cure strategies.

22 AREAS COVERED

This review covers the clinical features, genetics, immunopathogenesis and clinical management of WHIM syndrome. Clinical trials of targeted therapeutic agents and potential cure strategies are also included.

23 EXPERT OPINION

WHIM syndrome may be particularly amenable to mechanism-based therapeutics for three reasons: 1) CXCR4 has been validated as the molecular target in the disease by Mendelian genetics; 2) the biochemical abnormality is excessive CXCR4 signaling; and 3) antagonists selective for CXCR4 have been developed. Plerixafor is FDA-approved for hematopoietic stem cell (HSC) mobilization and has shown preliminary safety and efficacy in phase I clinical trials in WHIM syndrome. Gene editing may represent a viable cure strategy, since chromothriptic deletion of the disease allele in HSCs resulted in clinical cure of a patient and because CXCR4 haploinsufficiency enhances engraftment of transplanted HSCs in mice.

Description and outcome of a cohort of 8 patients with WHIM syndrome from the French Severe Chronic Neutropenia Registry

BACKGROUND

WHIM syndrome (WS), a rare congenital neutropenia due to mutations of the CXCR4 chemokine receptor, is associated with Human Papillomavirus (HPV)-induced Warts, Hypogammaglobulinemia, bacterial Infections and Myelokathexis. The long term follow up of eight patients highlights the clinical heterogeneity of this disease as well as the main therapeutic approaches and remaining challenges in the light of the recent development of new CXCR4 inhibitors.

OBJECTIVE

This study aims to describe the natural history of WS based on a French cohort of 8 patients.

METHODS

We have reviewed the clinical, biological and immunological features of patients with WS enrolled into the French Severe Chronic Neutropenia Registry.

RESULTS

We identified four pedigrees with WS comprised of eight patients and one foetus. Estimated incidence for WS was of 0.23 per million births. Median age at the last visit was 29 years. Three pedigrees encompassing seven patients and the fetus displayed autosomal dominant heterozygous mutations of the CXCR4 gene, while one patient presented a wild-type CXCR4 gene. Two subjects exhibited congenital conotruncal heart malformations. In addition to neutropenia and myelokathexis, all patients presented deep monocytopenia and lymphopenia. Seven patients presented repeated bacterial Ears Nose Throat as well as severe bacterial infections that were curable with antibiotics. Four patients with late onset prophylaxis developed chronic obstructive pulmonary disease (COPD). Two patients reported atypical mycobacteria infections which in one case may have been responsible for one patient's death due to liver failure at the age of 40.6 years. HPV-related disease manifested in five subjects and progressed as invasive vulvar carcinoma with a fatal course in one patient at the age of 39.5 years. In addition, two patients developed T cell lymphoma skin cancer and basal cell carcinoma at the age of 38 and 65 years.

CONCLUSIONS

Continuous prophylactic anti-infective measures, when started in early childhood, seem to effectively prevent further bacterial infections and the consequent development of COPD. Long-term follow up is needed to evaluate the effect of early anti-HPV targeted prophylaxis on the development of skin and genital warts.

Stromal-derived factor-1/CXCR4 signaling: indispensable role in homing and engraftment of hematopoietic stem cells in bone marrow

Homing and engraftment of hematopoietic stem/progenitor cells (HSPCs) in bone marrow is the major determining factor in success of hematopoietic stem cell transplantation. This is a complex, multistep process orchestrated by the coordinated interplay between adhesion molecules, cytokines, growth factors, and regulatory cofactors, many of which remain to be defined. Recent studies have highlighted the pivotal role of unique stromal-derived factor-1 (SDF-1)/CXCR4 signaling in the regulation of HSPC homing and subsequent engraftment. In addition, studies suggest that SDF-1/CXCR4 signaling acts as an essential survival-promoting factor of transplanted HSPCs as well as maintenance of quiescent HSCs in bone marrow niche. These pleiotropic effects exerted by SDF-1/CXCR4 axis make this unique signaling initiator very promising, not only for optimal hematopoietic reconstitution but also for the development of innovative approaches to achieve restoration, regeneration, or repair of other damaged tissues potentially amendable to reversal by stem cell transplantation. This goal can only be achieved when the role of SDF-1/CXCR4 axis in hematopoietic transplantation is clearly defined. Hence, this review presents current knowledge of the mechanisms through which SDF-1/CXCR4 signaling promotes restoration of hematopoiesis by regulating the homing and engraftment of HSPCs.

Genetic variation in CXCR4 and risk of chronic lymphocytic leukemia

A genome-wide linkage scan has provided evidence for a chronic lymphocytic leukemia (CLL) susceptibility locus at 2q21 to which the chemokine receptor CXCR4 gene maps. Recent data provide some evidence for common variation in CXCR4 according to the polymorphic variant rs2228014 defining CLL risk. To examine the role of genetic variation in CXCR4 on CLL risk, we screened 188 familial CLL cases and 213 controls for germline mutations in the coding regions of CXCR4 and genotyped rs2228014 in 1058 CLL cases and 1807 controls. No association between rs2228014 and risk of CLL was seen (P = .83). One truncating (W195X) and 2 missense mutations with possible functional consequences (V139I and G335S) were identified among 186 familial cases and 0 in 213 controls sequenced. Our analysis provides no evidence that common variation in CXCR4 defined by rs228014 influences the risk of CLL, but that functional coding mutations in CXCR4 may contribute to familial CLL.

WHIM syndrome: congenital immune deficiency disease

PURPOSE OF REVIEW

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is characterized by susceptibility to human papilloma virus infection-induced warts and carcinomas; neutropenia, B-cell lymphopenia and hypogammaglobulinema-related infections; and bone marrow myelokathexis (myeloid hyperplasia with apoptosis). The purpose of this report is to review new findings about WHIM.

RECENT FINDINGS

Most WHIM patients have heterozygous C-terminus deletion mutations of the intracellular carboxy terminus of the chemokine receptor CXCR4. WHIM leukocytes have enhanced responses to CXCL12, the cognate ligand of CXCR4. Enhanced activity of CXCR4 delays release of mature neutrophils from bone marrow, resulting in neutropenia and apoptosis of mature neutrophils retained in the marrow. Finding two patients with WHIM who do not have detectable mutations of CXCR4 but whose cells are hyperresponsive to CXCL12 raises the possibility that there is more than one genetic basis for WHIM. One patient had low levels of G-protein receptor kinase 3, and the functional hyperactivity response to CXCL12 was corrected by forced gene transfer-mediated overexpression of G-protein receptor kinase 3, implicating defects in function of this protein as a potential alternate genetic cause of WHIM.

SUMMARY

Subjects reviewed include clinical presentation, diagnosis, and treatment of WHIM and advances in understanding the genetic basis of WHIM.

Familial occurrence of warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome

Introduction:

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a rare immunodeficiency disorder with an autosomal-dominant pattern of inheritance and low fatality rate but significant lifelong morbidity.

Materials and Methods:

A 27-year-old mother of two children has been suffering from severe neutropenia and recurrent infections with the diagnosis of sporadic WHIM syndrome established by sequencing the CXCR4 gene and the finding of a heterozygous 1000 C→T nonsense mutation in the second CXCR4 exon. The first child was an apparently healthy boy delivered at full term. Umbilical cord blood cells were obtained for genetic analysis. Peripheral blood cells were also analyzed at 8 months of life. Both analyses revealed the same mutation as that of his mother. The child was in a good condition, manifesting neutropenia without infections until 11 months of life. He subsequently developed pneumonia requiring a more aggressive treatment. After that, the regular substitution of immunoglobulins (IVIGs) and G-CSF has been preventing serious infections. Six months ago the second boy was delivered who also demonstrated neutropenia without severe infections. Genetic studies using cord blood and also peripheral blood cells in the fourth month showed an identical mutation of the CXCR4 gene as in his mother. Moreover, the mother and her first son demonstrated monocytopenia.

Results:

The results indicate that genetic defects connected with WHIM syndrome may influence not only the granulocyte, but also the monocytic lineage. Moreover, a perinatal diagnosis of WHIM syndrome made by sequencing the CXCR4 gene should be performed in cases where either parent is known to be affected with this disease.

Conclusions:

This would facilitate an earlier detection of the deficiency in children, thereby allowing a more comprehensive follow-up and administration of appropriate therapy.

WHIM syndrome

A WHIM-szindróma ritka, autoszomális domináns öröklődésmenetű primer immunhiány-betegség, amelyre vírusos szemölcsök, hypogammaglobulinaemia, visszatérő fertőzések és myelokathexis jellemző. A közleményben a szerzők egy esetismertetés kapcsán mutatják be a betegség klinikumát, laboratóriumi eltéréseit, összefoglalják a kórkép molekuláris patomechanizmusával kapcsolatos ismereteket és kezelésének lehetőségeit. A szerzők szerint a betegség inkomplett megjelenése a késői felismerés és kezelés gyakori oka gyermekkorban.

Characterization of cDNA and genomic sequences encoding a canine chemokine receptor, CXCR4 and its ligand CXCL12

The interaction of chemokine receptor CXCR4 and its functional ligand CXCL12 plays a key role in bone marrow hematopoiesis, neuronal and cardiovascular development, and organization of the immune system. Despite the importance of the CXCL12-CXCR4 axis for regulating hematopoiesis, information on the canine CXCR4 and CXCL12 genes is insufficient. In this present study, we identified the canine counterparts of the CXCR4 and CXCL12 cDNAs and genes. The amino acid sequence encoding canine CXCR4 showed the structural characteristics of seven transmembrane domain G protein-coupled receptors and high homology with those of humans and other animals. Two isoforms, CXCL12 alpha and CXCL12 beta, were identified in dogs, as described in human and other animals. The gene structures for canine CXCR4 and CXCL12 were similar to those of other animals. The canine CXCL12 gene structure indicated that the transcripts of the isoforms arose from alternative mRNA splicing. A single nucleotide polymorphism (SNP) with synonymous substitution was observed in the exon of the canine CXCL12 gene. mRNAs encoding canine CXCR4 and CXCL12 were expressed widely and constitutively. Molecular homology and constitutive expression of CXCR4 and CXCL12 mRNAs in canine normal tissues suggests critical roles in hematopoiesis and trafficking of leukocytes, as shown in other animals.

WHIM syndrome myelokathexis reproduced in the NOD/SCID mouse xenotransplant model engrafted with healthy human stem cells transduced with C-terminus-truncated CXCR4

WHIM(warts, hypogammaglobulinemia, recurrent bacterial infection, and myelokathexis) syndrome is a rare immunodeficiency caused in many cases by autosomal dominant C-terminal truncation mutations in the chemokine receptor CXCR4. A prominent and unexplained feature of WHIM is myelokathexis (hypercellularity with apoptosis of mature myeloid cells in bone marrow and neutropenia). We transduced healthy human CD34(+) peripheral blood-mobilized stem cells (PBSCs) with retrovirus vector encoding wild-type (wt) CXCR4 or WHIM-type mutated CXCR4 and studied these cells ex vivo in culture and after engraftment in a nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mouse xenograft model. Neither wt CXCR4 nor mutated CXCR4 transgene expression itself enhanced apoptosis of neutrophils arising in transduced PBSC cultures even with stimulation by a CXCR4 agonist, stromal cell-derived factor-1 (SDF-1 [CXCL12]). Excess wt CXCR4 expression by transduced human PBSCs enhanced marrow engraftment, but did not affect bone marrow (BM) apoptosis or the release of transduced leukocytes into PB. However, mutated CXCR4 transgene expression further enhanced BM engraftment, but was associated with a significant increase in apoptosis of transduced cells in BM and reduced release of transduced leukocytes into PB. We conclude that increased apoptosis of mature myeloid cells in WHIM is secondary to a failure of marrow release and progression to normal myeloid cell senescence, and not a direct effect of activation of mutated CXCR4.

WHIM syndrome: a defect in CXCR4 signaling

The study of inherited immunodeficiencies has proven valuable in elucidating molecular signaling cascades underlying the developmental and functional regulation of the human immune system. The first example of a human immunologic disease caused by mutation of a chemokine receptor was provided by WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome, a rare, combined immunodeficiency featuring an unusual form of neutropenia. Subsequent studies following the initial description of mutations in the CXCR4 gene have revealed a striking concordance in the types of mutations observed, suggesting that impaired regulation of receptor signaling by truncation of the cytoplasmic tail domain is an essential aspect in disease pathogenesis. Biochemical studies have provided support for the model that impaired receptor downregulation leads to the characteristic immunologic and hematologic disturbances. Interestingly, these genetic studies have also identified phenocopies with the same clinical features but without mutation of CXCR4, suggesting that mutations in as yet uncharacterized downstream regulators of the receptor may be involved in a proportion of cases.

Mechanisms of Disordered Granulopoiesis in Congenital Neutropenia

Neutrophils are critical components of the innate immune response, and persistent neutropenia is associated with a marked susceptibility to infection. There are a number of inherited clinical syndromes in which neutropenia is a prominent feature. A study of these rare disorders has provided insight into the mechanisms regulating normal neutrophil homeostasis. Tremendous progress has been made at defining the genetic basis of these disorders. Herein, progress in understanding the genetic basis and molecular mechanisms of these disorders is discussed. We have focused our discussion on inherited disorders in which neutropenia is the sole or major hematopoietic defect.

Enhanced function with decreased internalization of carboxy-terminus truncated CXCR4 responsible for WHIM syndrome

OBJECTIVE

WHIM (warts, hypogammaglobulinemia, recurrent bacterial infection, myelokathexis) syndrome is an autosomal dominant immune deficiency with severe chronic neutropenia and marrow neutrophil apoptosis. Carboxy-termini truncating mutations in the chemokine receptor CXCR4 have been identified in WHIM patients. We created a retrovirus encoding mutated CXCR4 (truncating point mutation 1000C-->T [R334X] inherited heterozygously in several WHIM patients) in order to transducer healthy human CD34 stem cells and K562 to overexpress mutated CXCR4 and determined its effect on receptor responses to stromal-derived factor-1 (SDF1).

METHODS

Retrovirus vector was engineered to coexpress WHIM-associated R334X mutated CXCR4 together with green fluorescent protein (GFP). Control vectors included similar constructs with wild-type CXCR4 (WT-CXCR4) or only GFP. CD34+ cells and K562 were transduced with these vectors. Populations of 100% transduced K562 were established by sorting GFP+ cells by flow cytometry. We performed migration and calcium flux assays of transduced CD34+ cells and transduced/sorted K562. We also examined receptor recycling in response to SDF1.

RESULTS

Healthy human CD34+ cells and/or human erythroleukemia K562 cells transduced to express mutated CXCR4, WT-CXCR4, or GFP alone demonstrated that mutated CXCR4 was associated with enhanced calcium flux and enhanced migration. There was also decreased receptor internalization and enhanced recovery of surface mutated CXCR4 in response to SDF1 compared with WT-CXCR4.

CONCLUSION

We propose that decreased internalization of WHIM-associated mutated CXCR4 leads to prolongation/enhancement of signaling in response to SDF1 and that this may provide the biochemical basis for the autosomal dominant abnormalities of cell trafficking and function associated with WHIM syndrome.

CXCR4 mutations in WHIM syndrome: a misguided immune system?

Chemokines and their receptors are key molecules in the development and function of immune cell populations and the organization of lymphoid organs. Despite their central role in immunologic function, genetic studies exploring the intersection of chemokines or their receptors and human health have revealed few associations of unambiguous significance. The best-characterized examples have revealed striking selective advantage conferred by loss of receptors used as portals of entry by pathogens. Recently, mutations in the CXCR4 chemokine receptor gene were identified in a dominantly inherited immunodeficiency disease, WHIM syndrome. Genetic and biochemical evidences suggest that the loss of the receptor cytoplasmic tail domain results in aberrant signaling. Analyses of mutant cell responses to the receptor ligand CXCL12 have revealed enhanced chemotaxis, confirming the gain-of-function effect of the truncation mutations. The clinical features and potential mechanism of immunodeficiency in WHIM syndrome patients are discussed in this review.

Inherited disorders of cytokines

PURPOSE OF REVIEW

Cytokines are soluble mediators involved in the development or function of the immune system. This paper reviews the literature on childhood-onset inherited disorders associated with impaired cytokine-mediated immunity.

RECENT FINDINGS

Cytokine-mediated immunity defects can be classified into seven different groups: defects in the interleukin (IL)-7 receptor (IL7RA), in the common cytokine receptor gamma chain (gammac) of the IL-2, -4, -7, -15, and -21, and in Jak3 (JAK3) downstream of the gamma chain; mutation in the IL-2 receptor alpha (IL-2RA) and defective expression of the IL-2Rbeta chain; mutations in the gene encoding for a chemokine receptor, CXCR4; mutations in five genes involved in the IL-12/23-interferon-gamma axis (IL12B, IL12RB1, IFNGR1, IFNGR2, STAT1); mutations in three genes involved in the nuclear factor-kappaB signaling pathway (IRAK4, NEMO, IkappaBA); mutations in the tumor necrosis factor receptor signaling pathway (TNFRSF1A); and mutations in the transforming growth factor-1 gene (TGFB1).

SUMMARY

Genetic cytokine-mediated immunity defects are associated with a highly heterogeneous group of clinical features, ranging from susceptibility to infections to developmental defects. This heterogeneity highlights the diversity and pleiotropy of cytokines. It is likely that many more cytokine defects and their responsive pathways will be discovered in the coming years, expanding further the heterogeneity associated with this group of childhood-onset illnesses.

Update on childhood neutropenia: molecular and clinical advances

Congenital and inherited disorders are important differential diagnoses of neutropenia, particularly in neonates and children, although acquired causes are more common. This article focuses on recent advances in understanding the cellular and molecular defects in inherited neutropenias as well as issues that are related to clinical presentation, diagnosis, and complications.

WHIM syndrome: a genetic disorder of leukocyte trafficking

PURPOSE OF REVIEW

WHIM syndrome (the association of warts, hypogammaglobulinemia, recurrent bacterial infections, and 'myelokathexis') is a rare congenital form of neutropenia associated with an unusual immune disorder involving hypogammaglonulinemia and abnormal susceptibility to warts. In this review, we describe the clinical, laboratory and genetic features of WHIM syndrome.

RECENT FINDINGS

The identification of chemokine receptor CXCR4 as the causative gene of WHIM syndrome yields new interest in the study of this disease as a model for the comprehension of CXCR4 biology in humans and highlights the importance of the chemokine network for inducing effective immune responses and governing leukocyte trafficking.

SUMMARY

CXCR4 participates in several biological processes (bone marrow hematopoiesis, cardiogenesis, angiogenesis, neurogenesis) and is implicated in different clinical pathologic conditions (WHIM, HIV infection, tumor metastatization, autoimmunity). Pharmacologic agents that modulate CXCR4 expression/function are already available and promise a wide range of future clinical applications.

Infections in patients with inherited defects in phagocytic function

Patients with defects in phagocytic function are predisposed to intracellular microorganisms and typically have early dissemination of the infection. Recognition of the underlying disorder and aggressive antimicrobial therapy has been beneficial for the patients. Improved understanding of the pathophysiology has also affected patient management by allowing specific, targeted immunomodulatory intervention. The disorders described in this review are not common but have had a significant impact on our understanding of the role of phagocytic cells in host defense. Conversely, understanding the role of the neutrophil and macrophage in infection has benefited not just the patients described in this review but also other patients with similar disease processes.

Mutations in the chemokine receptor gene CXCR4 are associated with WHIM syndrome, a combined immunodeficiency disease

WHIM syndrome is an immunodeficiency disease characterized by neutropenia, hypogammaglobulinemia and extensive human papillomavirus (HPV) infection. Despite the peripheral neutropenia, bone marrow aspirates from affected individuals contain abundant mature myeloid cells, a condition termed myelokathexis. The susceptibility to HPV is disproportionate compared with other immunodeficiency conditions, suggesting that the product of the affected gene may be important in the natural control of this infection. We describe here the localization of the gene associated with WHIM syndrome to a region of roughly 12 cM on chromosome 2q21 and the identification of truncating mutations in the cytoplasmic tail domain of the gene encoding chemokine receptor 4 (CXCR4). Haplotype and mutation analyses in a pedigree transmitting myelokathexis as an apparently autosomal recessive trait support genetic heterogeneity for this aspect of the WHIM syndrome phenotype. Lymphoblastoid cell lines carrying a 19-residue truncation mutation show significantly greater calcium flux relative to control cell lines in response to the CXCR4 ligand, SDF-1, consistent with dysregulated signaling by the mutant receptor. The identification of mutations in CXCR4 in individuals with WHIM syndrome represents the first example of aberrant chemokine receptor function causing human disease and suggests that the receptor may be important in cell-mediated immunity to HPV infection.

B-cell lymphoma in a patient with WHIM syndrome

WHIM syndrome is a rare congenital familial syndrome consisting of warts, hypogammaglobulinemia, infections, and myelokathexis. We describe a 30-year-old man with WHIM syndrome, in whom red dermal facial nodules developed. The diagnosis of B-cell lymphoma was established with biopsy and immunohistochemical studies. To our knowledge, this is the first reported case of WHIM syndrome complicated by a B-cell lymphoma.

Dysplastic changes in idiopathic thrombocytopenic purpura and the effect of corticosteroids to increase dysplasia and cause hyperdiploid macropolycytes

This study evaluates the dysplastic hematological changes in nine patients with idiopathic thrombocytopenic purpura (ITP) in 11 attacks, before and after corticosteroid treatment. The pretreatment blood smears of patients with ITP, displayed more neutrophils with bizarre nuclei (P < 0.001), Döhle or Döhle-like inclusions (P < 0. 01), irregular distribution of granules (P < 0.05), hypo-agranulation (P < 0.05), pseudo-Pelger-Huet-like cells (P < 0. 01), and nuclei with chromatine clumping (P < 0.01) than the normal children. The eosinophils of ITP patients were also dysplastic, before treatment. The pretreatment diameter of the neutrophils and the percentage of macropolycytes were greater than those of the patients with viral infections and normal group (P < 0.05 for all). The percentage of neutrophils with bizarre nuclei and nuclei with chromatine clumping and the diameter of neutrophils and macropolycyte percentage increased with corticosteroid therapy (P < 0.01, < 0.01, < 0.01, and < 0.05, respectively). The neutrophil diameter, percentage of macropolycytes, and number of neutrophils with bizarre nuclei decreased within 1-4 weeks after the therapy was stopped. In the neutrophils of two patients, diploidy and hyperdiploidy were established before and on the last day of therapy, respectively, and diploidy reversed after therapy was stopped. In conclusion, ITP patients display dysplastic findings in both neutrophils and eosinophils before treatment and corticosteroids cause transient significant increase in some of the dysplastic changes in neutrophils.

A variant of myelokathexis with hypogammaglobulinemia: lymphocytes as well as neutrophils may reverse in response to infections

A 7-year-old boy with prolonged and marked leukopenia diagnosed at 6 months of age is described. The polymorphonuclear cells presented no hypersegmented nuclei or concentrated nuclear chromatin, although vacuolated myeloid cells appeared in bone marrow smears. Neutrophils reversed in response to administration of G-CSF. His leukocyte counts were 400-1000/microL during afebrile periods and increased to 2000-3000/microL in response to infections. The increased leukocyte was usually neutrophils, but lymphocytes also increased at EB-virus infection. The serum IgG decreased gradually and was 364 mg/dL at 7 years of age. Antibody responses were normal and recurrent otitis media has been the patient's only problem. Granulocytopenia with hypogammaglobulinemia of this patient mimics myelokathexis with hypogammaglobulinemia, and lymphocytes also increased at viral infections.

Myelokathexis, a congenital disorder of severe neutropenia characterized by accelerated apoptosis and defective expression ofbcl-x in neutrophil precursors

Myelokathexis is a congenital disorder that causes severe chronic leukopenia and neutropenia. Characteristic findings include degenerative changes and hypersegmentation of mature neutrophils and hyperplasia of bone marrow myeloid cells. The associated neutropenia can be partially corrected by treatment with granulocyte colony-stimulating factor (G-CSF) or granulocyte–macrophage colony-stimulating factor (GM-CSF). These features led us to propose that accelerated apoptosis of neutrophil precursors might account for the neutropenic phenotype. Blood and bone marrow aspirates were obtained from 4 patients (2 unrelated families) with myelokathexis before G-CSF therapy and from 2 of the affected persons after G-CSF therapy (1 μg/kg per day subcutaneously for 3 weeks). Bone marrow was fractionated using immunomagnetic bead cell sorting into CD34+, CD33+/CD34−, and CD15+/CD34−/CD33− cell populations. Examination of these cells by flow cytometry and electron microscopy revealed abundant apoptosis in the CD15+ neutrophil precursor population, characterized by enhanced annexin-V binding, extensive membrane blebbing, condensation of heterochromatin, and cell fragmentation. Colony-forming assays demonstrated significant reduction in a proportion of bone marrow myeloid-committed progenitor cells. Immunohistochemical analysis revealed a selective decrease inbcl-x, but not bcl-2, expression in the CD15+/CD34−/CD33− cell population compared with similar subpopulations of control bone marrow-derived myeloid precursors. After G-CSF therapy, apoptotic features of patients' bone marrow cells were substantially reduced, and the absolute neutrophil counts (ANC) and expression ofbcl-x in CD15+/CD34−/CD33−cells increased. The authors concluded that myelokathexis is a disease characterized by the accelerated apoptosis of granulocytes and the depressed expression of bcl-x in bone marrow-derived granulocyte precursor cells. These abnormalities are partially corrected by the in vivo administration of G-CSF. (Blood. 2000;95:320-327)

Myelokathexis, a congenital disorder of severe neutropenia characterized by accelerated apoptosis and defective expression ofbcl-x in neutrophil precursors

Myelokathexis is a congenital disorder that causes severe chronic leukopenia and neutropenia. Characteristic findings include degenerative changes and hypersegmentation of mature neutrophils and hyperplasia of bone marrow myeloid cells. The associated neutropenia can be partially corrected by treatment with granulocyte colony-stimulating factor (G-CSF) or granulocyte–macrophage colony-stimulating factor (GM-CSF). These features led us to propose that accelerated apoptosis of neutrophil precursors might account for the neutropenic phenotype. Blood and bone marrow aspirates were obtained from 4 patients (2 unrelated families) with myelokathexis before G-CSF therapy and from 2 of the affected persons after G-CSF therapy (1 μg/kg per day subcutaneously for 3 weeks). Bone marrow was fractionated using immunomagnetic bead cell sorting into CD34+, CD33+/CD34−, and CD15+/CD34−/CD33− cell populations. Examination of these cells by flow cytometry and electron microscopy revealed abundant apoptosis in the CD15+ neutrophil precursor population, characterized by enhanced annexin-V binding, extensive membrane blebbing, condensation of heterochromatin, and cell fragmentation. Colony-forming assays demonstrated significant reduction in a proportion of bone marrow myeloid-committed progenitor cells. Immunohistochemical analysis revealed a selective decrease inbcl-x, but not bcl-2, expression in the CD15+/CD34−/CD33− cell population compared with similar subpopulations of control bone marrow-derived myeloid precursors. After G-CSF therapy, apoptotic features of patients' bone marrow cells were substantially reduced, and the absolute neutrophil counts (ANC) and expression ofbcl-x in CD15+/CD34−/CD33−cells increased. The authors concluded that myelokathexis is a disease characterized by the accelerated apoptosis of granulocytes and the depressed expression of bcl-x in bone marrow-derived granulocyte precursor cells. These abnormalities are partially corrected by the in vivo administration of G-CSF. (Blood. 2000;95:320-327)

Dizygotic twin sisters with myelokathexis: mechanism of its neutropenia

Dizygotic twin sisters were first found to have neutropenia at 1 year of age when evaluated for recurrent pulmonary infections. Since then they have remained neutropenic (0.05 approximately 0.5 x 10(9)/l). Despite of their neutropenia, myeloid hyperplasia was evident on a marrow smear examination, and a number of cells were hypersegmented with fine interlobular bridging with chromatin strands and cytoplasmic vacuolation. Electron microscopy showed apoptotic cells with condensed nuclei and apoptotic bodies in the cytoplasm. Although life span, hydrogen peroxide production, phagocytosis, spreading, and chemotaxis of peripheral neutrophils were normal, the survival of bone marrow neutrophils in both infants was markedly decreased when compared with that of normal bone marrow neutrophils. During the bone marrow culture apoptotic neutrophils were observed at an earlier stage in both patients than in normal controls, biochemically and morphologically. Morphology of bone marrow neutrophils in both patients resembled that of cultured control bone marrow neutrophils. Peripheral neutropenia and appearance of characteristic neutrophils in the bone marrow in myelokathexis are considered to be an expression of apoptosis of bone marrow neutrophils.

Clinical features of myelokathexis and treatment with hematopoietic cytokines: a case report of two patients and review of the literature

PURPOSE

To define the features and course of myelokathexis, a rare congenital neutropenia resulting from impaired release of granulocytes from bone marrow.

METHODS

The clinical features, granulocyte function, lymphocyte function, and response to granulocyte colony-stimulating factor (G-CSF) of two patients (mother/son) with myelokathexis were studied. This experience and 14 previous reports lead to a composite description of myelokathexis.

RESULTS

Both patients had chronic neutropenia, recurrent pulmonary infections, bone marrow consistent with myelokathexis, hypogammaglobulinemia, and elevated endogenous G-CSF. Patient 15 had normal granulocyte function, a rise in absolute neutrophil count (ANC) with epinephrine and hydrocortisone, and normal numbers of T- and B-lymphocytes; she also had numerous warts during childhood. Both patients experienced a transient increase in ANC with infection, a significant increase in ANC within 5 hours following a single dose of G-CSF, and fewer infections with daily G-CSF.

CONCLUSIONS

Based on 16 cases, myelokathexis occurs more often in females and frequently affects multiple members of a family. The usual number of circulating granulocytes is low although function is normal. Mature marrow granulocytes are mobilized with infection, corticosteroids, epinephrine, G-CSF, and granulocyte-macrophage colony-stimulating factor (GM-CSF). Lymphocyte number is normal but lymphocyte function is abnormal as evidenced by hypogammaglobulinemia and papillomavirus infection.

Non-malignant neutropenia

Neutropenia occurs when the production of neutrophils by the bone marrow is outpaced by utilization in the periphery. Abnormalities of hematopoietic stem-cell development and decreased proliferation of neutrophil precursors in the marrow can reduce production of neutrophils. Conversely, decreased neutrophil survival in the peripheral circulation can also give rise to neutropenia. Non-malignant neutropenia of acute onset can be caused by infection, antibody-mediated destruction, or an idiosyncratic reaction to a drug. Severe chronic neutropenia is a global, descriptive term for several disorders of varied etiologies in which neutrophil levels are consistently or recurrently at levels less than 0.5 x 10(9)/L. Despite this heterogeneity of origin, administration of recombinant human granulocyte colony stimulating factor to individuals with severe chronic neutropenia results in an increase in neutrophil counts in most patients associated with a significantly improved quality of life.

Clinical and biologic effects of granulocyte colony stimulating factor in the treatment of myelokathexis

Successful treatment of a patient with myelokathexis, a rare form of chronic neutropenia associated with recurrent infections, is described. Rapid mobilization of bone marrow neutrophils and improved myeloid morphologic features were observed after treatment with human granulocyte colony stimulating factor. Transient thrombocytopenia and bone pain were observed during treatment. Although neutrophil chemotaxis, superoxide production, and FcRIII surface expression were reduced, the patient improved clinically after restoration of a normal neutrophil count.

A myelokathexis-like variant of myelodysplasia

A 34-year-old woman presented with pancytopenia, profound neutropenia and repeated infections. A bone marrow specimen revealed hypercellularity with trilineage dysplasia and bizarre granulocytic morphology identical to that of the rarely reported myelokathexis. Investigations revealed defects in platelet and neutrophil functions and markedly reduced colony-to-cluster ratio in bone marrow culture. She required treatment with antibiotics, surgical intervention for a gangrenous abdominal wall, and eventually underwent a successful allogeneic bone marrow transplant from her sister. This case suggests that myelokathexis is an unusual form of myelodysplasia with a relatively benign course and presenting at a young age.

Myelokathexis associated with multiple congenital malformations: immunological study on phagocytic cells and lymphocytes

A 5-year-old boy was first seen at the age of 11 months when he presented with growth retardation, skeletal dysmorphisms and neutropenia. Since then he has remained leukopenic except when he has pulmonary infections with a marked leukocytosis. Despite his neutropenia, marked myeloid hyperplasia was evident on marrow smear examination; many cells showed abnormally hypersegmented nuclei, with unusual shape or pyknotic nuclei. Phagocytic cells showed impaired phagocytosis, candidacidal activity, metabolic burst and chemotaxis. Moreover, the patient's serum generated less chemotactic activity than normal serum. These data indicate a selectively complex defect of the neutrophil during differentiation associated with the presence of an inhibitor of chemotactic factors in the patient's serum.

Myelokathexis: a rare form of chronic benign granulocytopenia

A case of childhood chronic neutropenia due to myelokathexis is reported. This extremely rare condition (the fourth case in the literature) has been diagnosed from the characteristic bone marrow abnormalities in the neutrophils.

Myelokathexis: chronic neutropenia with hyperplastic bone marrow and hypersegmented neutrophils in two siblings

The author describes the clinical and pathological characteristics of a chronic neutropenia in two siblings. The disease was probably inherited as an autosomal recessive trait. The clinical course and the results of the laboratory investigations corresponded to the rare cases of "myelokathexis" reported so far.

Neutrophil marrow profiles in patients with rheumatoid arthritis and neutropenia

Neutrophil marrow cellularity was determined in 14 neutropenic patients with rheumatoid arthritis (RA) from measurements of neutrophil-normoblast ratios in marrow biopsies and ferrokinetic estimates of marrow normoblasts. A marrow profile was developed for each patient comprising the numbers of promyelocytes and myelocytes, of metamyelocytes and bands, and of segmented neutrophils in whole marrow. In each case a maturation ratio was calculated by dividing the number of metamyelocytes and bands by the number of promyelocytes and myelocytes. The physiologic marrow response to loss of neutrophils from circulation was assumed to be an increase in promyelocytes and myelocytes due to proliferation and influx, a reduction in segmented cells due to early release, and a normal maturation ratio. The results were interpreted in the light of the 95% confidence limits for data previously obtained from 13 normal subjects: in patients with neutropenia reduced or basal numbers of promyelocytes and myelocytes were interpreted as absence of the anticipated proliferative response; increased numbers of marrow segmented cells were attributed to failure of release; a low maturation ratio was assessed to reflect intramedullary cell loss. The pattern in two patients with Felty's syndrome was consistent with a physiological response to neutrophil destruction. The other 12 patients had neutrophil marrow abnormalities. Seven patients with Felty's syndrome and four patients without splenomegaly had absolute or relative hypoplasia of neutrophil marrow or low maturation ratios. One patient with a normal spleen size had an increased number of marrow segmented cells yet failed to mobilize cells normally in response to dialysis coil-activation of C3. Abnormalities of neutrophil marrow may contribute to neutropenia in RA irrespective of the presence of splenomegaly. Recognition of neutrophil marrow abnormalities in these patients may be of value in prognosis and management.