Michaela Calvillo

B cell–helper neutrophils stimulate the diversification and production of immunoglobulin in the marginal zone of the spleen

Neutrophils utilize immunoglobulins (Igs) to clear antigen, but their role in Ig production is unknown. Here we identified neutrophils around the marginal zone (MZ) of the spleen, a B cell area specialized in T-independent Ig responses to circulating antigen. Neutrophils colonized peri-MZ areas after post-natal mucosal colonization by microbes and enhanced their B-helper function upon receiving reprogramming signals from splenic sinusoidal endothelial cells, including interleukin 10 (IL-10). Splenic neutrophils induced Ig class switching, somatic hypermutation and antibody production by activating MZ B cells through a mechanism involving the cytokines BAFF, APRIL and IL-21. Neutropenic patients had fewer and hypomutated MZ B cells and less preimmune Igs to T-independent antigens, which indicates that neutrophils generate an innate layer of antimicrobial Ig defense by interacting with MZ B cells.Neutrophils use immunoglobulins to clear antigen, but their role in immunoglobulin production is unknown. Here we identified neutrophils around the marginal zone (MZ) of the spleen, a B cell area specialized in T cell–independent immunoglobulin responses to circulating antigen. Neutrophils colonized peri-MZ areas after postnatal mucosal colonization by microbes and enhanced their B cell–helper function after receiving reprogramming signals, including interleukin 10 (IL-10), from splenic sinusoidal endothelial cells. Splenic neutrophils induced immunoglobulin class switching, somatic hypermutation and antibody production by activating MZ B cells through a mechanism that involved the cytokines BAFF, APRIL and IL-21. Neutropenic patients had fewer and hypomutated MZ B cells and a lower abundance of preimmune immunoglobulins to T cell–independent antigens, which indicates that neutrophils generate an innate layer of antimicrobial immunoglobulin defense by interacting with MZ B cells.

Diagnostic potential of hepcidin testing in pediatrics

Hepcidin, a peptide hormone released by hepatocytes into circulation is the main regulator of dietary iron absorption and cellular iron release. Although commercial tests are available, assay harmonization for hepcidin has not been yet reached, making reference intervals and consequent clinical decisions still elusive for each assay and specific population. The aim of this study is to set up hepcidin measurement in pediatric age and to investigate its potential usefulness in the diagnosis and management of iron disorders in children.

Severe lactic acidosis due to thiamine deficiency in a patient with B-cell leukemia/lymphoma on total parenteral nutrition during high-dose methotrexate therapy.

An 11-month-old girl with B-cell leukemia/lymphoma developed profound lethargy due to severe lactic acidosis during chemotherapy and total parenteral nutrition (TPN). Initial treatment with NaHCO3 was ineffective. Treatment with a vitamin cocktail (OH-cobalamin, pyridoxine, thiamine, riboflavine, biotin, carnitine) at pharmacologic doses rapidly improved the childs clinical and laboratory status. Lactic acidosis was caused by an impairment of pyruvate dehydrogenase complex, which was due to lack of its necessary cofactor thiamine in the TPN. This case report indicates that lactic acidosis may be a front-line diagnosis in patients on TPN with lethargy and outlines the need for monitoring thiamine supply in TPN.

Stem cell transplantation in severe congenital neutropenia: an analysis from the European Society for Blood and Marrow Transplantation.

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment of severe congenital neutropenia (SCN), but data on outcome are scarce. We report on the outcome of 136 SCN patients who underwent HSCT between 1990 and 2012 in European and Middle East centers. The 3-year overall survival (OS) was 82%, and transplant-related mortality (TRM) was 17%. In multivariate analysis, transplants performed under the age of 10 years, in recent years, and from HLA-matched related or unrelated donors were associated with a significantly better OS. Frequency of graft failure was 10%. Cumulative incidence (day +90) of acute graft-versus-host disease (GVHD) grade 2-4 was 21%. In multivariate analysis, HLA-matched related donor and prophylaxis with cyclosporine A and methotrexate were associated with lower occurrence of acute GVHD. Cumulative incidence (1 year) of chronic GVHD was 20%. No secondary malignancies occurred after a median follow-up of 4.6 years. These data show that the outcome of HSCT for SCN from HLA-matched donors, performed in recent years, in patients younger than 10 years is acceptable. Nevertheless, given the TRM, a careful selection of HSCT candidates should be undertaken.

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. Pediatr Blood Cancer 2011;57:10–17.

Clofarabine, cyclophosphamide and etoposide for the treatment of relapsed or resistant acute leukemia in pediatric patients

Abstract Clofarabine is a promising new chemotherapeutic agent that is active in the treatment of pediatric acute leukemia. Forty children (16 with acute myeloid leukemia [AML], 24 with acute lymphoblastic leukemia [ALL]), aged 1–20 years (median 7.6 years) with relapsed or refractory ALL or AML were treated because of resistance to first-line treatment (n =5), or for first (n =22), second (n =11) or third relapse (n =2). They received clofarabine (40 mg/m2/day) associated with etoposide (100 mg/m2/day) and cyclophosphamide (440 mg/m2/day) administered as one or two induction cycles (5 days of chemotherapy) in an attempt to reach complete remission (CR) or CR without platelet recovery (CRp). This was followed by 1–3 consolidation cycles (4 days of chemotherapy) for a maximum of four cycles. Seven (44%) out of 16 and 10 (42%) out of 24 evaluable children with AML and ALL, respectively, responded to treatment. The most common adverse events were infections and gastrointestinal and hepatic toxicity. Thirteen (76%) out of 17 responders underwent hematopoietic stem cell transplant. The 24-month overall survival was 25%, while it was 59% among patients who responded to the first induction cycle. Our study suggests that this drug regimen is well tolerated and can be effective in heavily pretreated pediatric patients with relapsed or refractory acute leukemia.

Voriconazole for cryptococcal meningitis in children with leukemia or receiving allogeneic hemopoietic stem cell transplant.

Cryptococcus neoformans is an encapsulated heterobasidiomycetous that represents a major human pathogen in immunocompromised hosts 1, but invasive cryptococcosis is a rare complication during chemotherapy in patients with acute leukemia or following allogeneic hemopoietic stem cell transplant (HsCT) 2-6. The clinical picture of C. neoformans infections varies from asymptomatic colonization of the respiratory tract to disseminated disease, with meningitis being the most frequent clinical picture 1. Amphotericin B is the golden standard therapy for cryptococcosis, and its association with flucytosine leads to more rapid clearance of the fungus from the cerebrospinal fluid (CsF) 7,8. After treating the invasive infection, long term prophylaxis is required in patients persistently immunocompromised, and fluconazole represents the drug of choice 8. Other triazoles, such as itraconazole and voriconazole, have been proven to be active in vitro against C. neoformans 9. We report two cases of invasive C. neoformans meningitis infections in immunocompromised children who were successfully managed with voriconazole. Case 1: The first patient was a 6-year-old girl affected with acute lymphoblastic leukemia who developed pneumonia with severe acute respiratory insufficiency that required mechanical ventilation during administration of high dose dexamethasone for the treatment of her leukemia. Blood cultures showed the presence of yeasts that were subsequently identified as C. neoformans, and the search for the cryptococcal antigen in the serum was positive. she received antifungal therapy with liposomal amphotericin B (3 mg/kg/q24 h) that led to an improvement in her condition. After 3 weeks of this treatment, serum antigen became negative and fluconazole prophylaxis (10 mg/kg/q24 h) was started. One week later, fever reappeared and serum cryptococcal antigen became positive again. she received liposomal amphotericin B at the same dosage for another week and achieved negative antigen, but abdominal ultrasound demonstrated the presence of spleen nodules. Moreover, cryptococcal antigen was also positive in the CsF despite the absence of clinical signs of central nervous system involvement. since the patient desired to be discharged from the hospital, voriconazole was administered (7 mg/kg q12 h for 3 days, then 200 mg q12 h orally, on empty stomach) because of the availability of an oral formulation that allowed good compliance and considering its in vitro activity, ability to cross the blood-brain barrier, the failure of fluconazole prophylaxis and the persistence of antigen in the CsF. Cryptococcal antigen in the CsF resulted negative after 10 days of voriconazole. This drug was administered until 7 months after elective discontinuation of chemotherapy without any reactivation of the infection or any adverse effects. The patient relapsed with her acute lymphoblastic leukemia 2 months after discontinuation of voriconazole. At this time, cryptococcal antigen resulted negative both in the blood and CsF. she received an allogeneic HsCT from her brother after a myeloablative-conditioning regimen including body irradiation. During the first 100 days after HsCT she received fluconazole as prophylaxis (6 mg/kg/q24 h) for invasive mycosis on the basis of our standard procedures, and C. neoformans was never again detected in the blood or in the CsF. Case 2: The second patient was an 18-year-old boy with incomplete immunological reconstitution (CD4+ lymphocytes, 9%, 54/cmm and absence of CD19+/CD20+ lymphocytes) after alternative donor HsCT. He developed sudden fever associated with impaired consciousness, headache, blurred vision and rash 36 months after HsCT. Magnetic Resonance imaging showed the presence of mild intracranial hypertension and C. neoformans was isolated from cerebrospinal fluid. in view of the fact that the patient RepRint

Rituximab‐based immunosuppression for autoimmune haemolytic anaemia in infants

We report a case series of four infants with severe autoimmune haemolytic anaemia (AIHA) who responded to treatment with rituximab and cyclosporine after having failed first line therapy with high‐dose steroid (prednisolone 4–8 mg/kg/d). Rituximab was started at 11–90 d from onset due to continued haemolysis; three infants also received cyclosporine A. Three of four infants reached complete response, defined as normal haemoglobin, reticulocytes and negative indices of haemolysis, at 7–21 months from diagnosis. In long‐term follow‐up two infants remained disease‐free with normal immunology, one had undefined immunodeficiency and one had autoimmune lymphoproliferative syndrome.

Infectious complications in children with severe congenital, autoimmune or idiopathic neutropenia: a retrospective study from the Italian Neutropenia Registry.

We describe the incidence and characteristics of infections in children with severe congenital neutropenia (SCN), autoimmune neutropenia (AN) and idiopathic neutropenia (IN). Data extracted from the Italian Neutropenia Registry on 73 patients with 108 episodes of infections were collected from 2000 to 2009. All SCN patients with SCN and one third of AN and IN experienced at least 1 infectious episode, equating to 5.7 infections/patient in SCN and approximately 0.6 in AN and IN. The rate of infections before diagnosis of neutropenia was 6.35/1000 patient-days at risk in SCN, 0.48 in AN and 0.71 in IN (P < 0.001) and significantly decreased after diagnosis. Skin and subcutaneous abscesses and cellulitis were the most frequent types of infection encountered, followed by pneumonia. Infections are an important clinical issue in the management of neutropenic patients, even in those considered at lower risk.

Pegfilgrastim in children with severe congenital neutropenia

Two pediatric patients affected by severe congenital neutropenia (SCN) were treated with 100 mcg/L/dose every 9–12 days within a pilot study (Observatory of the Italian Ministry of Health, Eudract Code 2005‐003096‐20) on the use of pegfilgrastim in patients with chronic neutropenia. Both children increased their absolute neutrophil count, reduced their infectious load, and improved their quality of life. Serum concentrations of G‐CSF observed in pegfilgrastim mirrored those seen in filgrastim. These data suggest that pegfilgrastim may be beneficial in SCN patients with an exposure of hematopoietic cells to G‐CSF similar to that on filgrastim. Pediatr Blood Cancer 2010;54:465–467.