Israel Medical Association Journal

In Israel, Yemenite Jews and other populations including Ethiopian Jews and Bedouins have a low neutrophil count. This phenomenon has been called “benign neutropenia” since it has not been associated with any increased risk of infection and has also been described in other populations around the world including Africans, African Americans and Afro-Carribeans. Here we describe the recent success in mapping the gene that underlies benign neutropenia in African American populations. We discuss the known function of the gene and consider potential mechanisms for the effect on neutropenia. We also consider the possibility that this gene underlies the same effect observed in Yemenite Jews, Ethiopian Jews and Bedouins in Israel.
 

Background: Autoimmune neutropenia of infancy is caused by neutrophil-specific autoantibodies. Primary AIN[1] is characterized by neutrophil count < 500 ml and a benign self-limiting course. Detecting specific antibodies against the polymorphic human neutrophil antigen usually confirms the diagnosis. Current available tests, however, are expensive and inapplicable in many laboratories as they require the use of isolated and fixed granulocytes obtained from donors pretyped for their distinct HNA[2] alloform.

Objectives: To assess the performance of a modified test to identify by FACS-analysis granulocyte-specific antibodies in the sera of neutropenic children.

Methods: We evaluated 120 children with a clinical suspicion of AIN, whose sera were analyzed by flow cytometry for the presence of autoantibodies using the indirect granulocyte immunofluorescence test. In contrast to the traditional tests, the sera were tested against randomly selected untyped neutrophils derived from a batch of 10 anonymous healthy subjects, presumably including the common HNA alloforms. Control sera samples were from patients with chemotherapy-induced, familial or congenital neutropenias. To further assure the quality of the new test, we retested six samples previously tested by the gold standard method. All medical files were screened and clinical outcomes were recorded.

Results: Our method showed specificity of 85%, sensitivity of 62.5%, and a positive predictive value of 91.8%, values quite similar to those obtained by more traditional methods.

Conclusions: The new method showed high specificity for detection of anti-neutrophil antibodies in the appropriate clinical setting and could be an effective aiding tool for clinical decision making.

Background: Monitoring the rate of infections in individual centers that treat patients with hematological malignancies is of major importance. However, there are no uniform guidelines for infection surveillance.

Objectives: To describe the epidemiology of bacterial and fungal infections in a single hematology ward and to compare methods for reporting surveillance and infection rates in other centers in Israel.

Methods: We conducted a prospective surveillance of all patients admitted to our hematology ward, applying standard definitions for invasive fungal infections and adapting definitions for non-fungal infections. Incidence rates were calculated using patients, admissions, hospital days and neutropenia days. We performed a search for other reported surveillance studies in Israel.

Results: We detected 79 infectious episodes among 159 patients admitted to the hematology ward during 1 year. Using neutropenia days as the denominator for calculation of incidence discriminated best between patients at high and low risk for infection. The incidence of invasive fungal infections was 7, 10 and 18 per 1000 neutropenia days, among all patients, those with acute leukemia and those with acute leukemia undergoing induction therapy, respectively. Only 10 reports from Israel were identified, 6 of which were prospective. Our data could not be compared to these reports because of the varying definitions and denominators used.

Conclusions: Hematology centers should monitor infection rates and report them in a uniform methodology.
 

Background: The epidemiology of bacteremic febrile neutropenia differs between locations and constitutes the basis for selection of empiric antibiotic therapy for febrile neutropenia.

Objectives: To describe the epidemiology of bacteremia among patients with neutropenia in a single center in Israel.

Methods: We conducted a prospective data collection on all patients with neutropenia (< 500/mm³) and clinically significant bacteremia or fungemia during the period 1988–2004.

Results: Among adults (462 episodes) the most common bloodstream isolate was Esherichia coli. Gram-negative bacteria predominated throughout the study period and the ratio between Gram-negative and Gram-positive bacteremia increased from 1.7 to 2.3 throughout the study period. Among children (752 episodes), the ratio between Gram-negative and Gram-positive bacteremia reversed from 1.2 to 0.7, due to increasing prevalence of coagulase-negative staphylcoccal bacteremia. Both among adults and children, the length of hospital stay prior to bacteremia had a major impact on the pathogens causing bacteremia and their antibiotic susceptibilities. The prevalence of E. coli decreased with time in hospital, while the rates of Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterobacter spp., Acinetobacter spp., Enterococcus spp. and Candida spp. increased. Resistance to broad-spectrum empiric monotherapy in our center was observed in > 40% of Gram-negative bacteria when bacteremia was acquired after 14 days in hospital.
Conclusions: Improved infection-control measures for neutropenic cancer patients in our center are needed. Empiric antibiotic treatment should be tailored to patients’ risk for multidrug-resistant organisms. Individual hospitals should monitor infection epidemiology among cancer patients to guide empiric antibiotic treatment

Background: Granulocyte colony-stimulating factor has had a major impact on the management of severe chronic neutropenia – a collective term referring to congenital, idiopathic, or cyclic neutropenia. Almost all patients respond to G-CSF[1] with increased neutrophils, reduced infections, and improved survival. Some responders with congenital neutropenia (termed Kostmann’s syndrome herein) and Shwachman-Diamond syndrome have developed myelodysplastic syndrome and acute myeloid leukemia, which raises the question of the role of G-CSF in pathogenesis. The issue is complicated because both disorders have a propensity for MDS[2] or AML[3] as part of their natural history.

Objective and Methods: To address this, the Severe Chronic Neutropenia International Registry used its large database of chronic neutropenia patients treated with G-CSF to determine the incidence of malignant myeloid transformation in the two disorders, and its relationship to treatment and to other patient characteristics.

Results: As of January 2001, of the 383 patients with congenital forms of neutropenia in the Registry, 48 had MDS or AML (crude rate, about 12.5%). No statistically significant relationships were found between age at onset of MDS or AML and patient gender, G-CSF dose, or duration of G-CSF therapy. What was observed, however, was the multistep acquisition of aberrant cellular genetic changes in marrow cells from Kostmann’s syndrome patients who transformed, including activating ras oncogene mutations, clonal cytogenetic abnormalities, and G-CSF receptor mutations. The latter in murine models produces a hyperproliferative response to G-CSF, confers resistance to apoptosis, and enhances cell survival.

Conclusions: Since Kostmann’s syndrome and Shwachman-Diamond syndrome are inherited forms of bone marrow failure, G-CSF may accelerate the propensity for MDS/AML in the genetically altered stem and progenitor cells, especially in those with G-CSF receptor and ras mutations (82% and 50% of Kostmann’s syndrome patients who transform, respectively). Alternatively, and equally plausible, G-CSF may simply be an innocent bystander that corrects neutropenia, prolongs patient survival, and allows time for the malignant predisposition to declare itself. Only careful long-term follow-up of the cohort of patients receiving G-CSF will provide the answer.

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[1] G-CSF = granulocyte colony-stimulating factor

[2] MDS = myelodysplastic syndrome

[3] AML = acute myeloid leukemia