Carla Boschetti

Complement fraction 3 binding on erythrocytes as additional mechanism of disease in paroxysmal nocturnal hemoglobinuria patients treated by eculizumab

In paroxysmal nocturnal hemoglobinuria (PNH) hemolytic anemia is due mainly to deficiency of the complement regulator CD59 on the surface of red blood cells (RBCs). Eculizumab, an antibody that targets complement fraction 5 (C5), has proven highly effective in abolishing complement-mediated intravascular hemolysis in PNH; however, the hematologic benefit varies considerably among patients. In the aim to understand the basis for this variable response, we have investigated by flow cytometry the binding of complement fraction 3 (C3) on RBCs from PNH patients before and during eculizumab treatment. There was no evidence of C3 on RBCs of untreated PNH patients; by contrast, in all patients on eculizumab (n = 41) a substantial fraction of RBCs had C3 bound on their surface, and this was entirely restricted to RBCs with the PNH phenotype (CD59(-)). The proportion of C3(+) RBCs correlated significantly with the reticulocyte count and with the hematologic response to eculizumab. In 3 patients in whom (51)Cr labeling of RBCs was carried out while on eculizumab, we have demonstrated reduced RBC half-life in vivo, with excess (51)Cr uptake in spleen and in liver. Binding of C3 by PNH RBCs may constitute an additional disease mechanism in PNH, strongly enhanced by eculizumab treatment and producing a variable degree of extravascular hemolysis.

Congenital dyserythropoietic anemia type II (CDAII) is caused by mutations in the SEC23B gene

Congenital dyserythropoietic anemia type II (CDAII) is an autosomal recessive disease characterized by ineffective erythropoiesis, hemolysis, erythroblast morphological abnormalities, and hypoglycosylation of some red blood cell (RBC) membrane proteins. Recent studies indicated that CDAII is caused by a defect disturbing Golgi processing in erythroblasts. A linkage analysis located a candidate region on chromosome 20, termed the CDAN2 locus, in the majority of CDAII patients but the aberrant gene has not so far been elucidated. We used a proteomic‐genomic approach to identify SEC23B as the candidate gene for CDAII by matching the recently published data on the cytoplasmic proteome of human RBCs with the chromosomic localization of CDAN2 locus. Sequencing analysis of SEC23B gene in 13 CDAII patients from 10 families revealed 12 different mutations: six missense (c.40C>T, c.325G>A, c.1043A>C, c.1489C>T, c.1808C>T, and c.2101C>T), two frameshift (c.428_428delAinsCG and c.1821delT), one splicing (c.689+1G>A), and three nonsense (c.568C>T, c.649C>T, and c.1660C>T). Mutations c.40C>T and c.325G>A were detected in unrelated patients. SEC23B is a member of the Sec23/Sec24 family, a component of the COPII coat protein complex involved in protein transport through membrane vesicles. Abnormalities in this gene are likely to disturb endoplasmic reticulum (ER)‐to‐Golgi trafficking, affecting different glycosylation pathways and ultimately accounting for the cellular phenotype observed in CDAII. Hum Mutat 30:1–7, 2009.

Clinical and hematologic features of 300 patients affected by hereditary spherocytosis grouped according to the type of the membrane protein defect

The molecular basis of hereditary spherocytosis is highly heterogeneous, involving the genes encoding for spectrin, ankyrin, band 3 and protein 4.2. The findings of this retrospective study show that splenectomy corrected anemia in patients with all molecular subtypes of hereditary spherocytosis. Thus, the definition of the red cell membrane defect in hereditary spherocytosis has no major clinical implications, but may be useful for a differential diagnosis from other hematologic disorders that mimic this hemolytic anemia. See related perspective article on page 1283. Background Hereditary spherocytosis is a very heterogeneous form of hemolytic anemia. The aim of this study was to relate the type of molecular defect with clinical and hematologic features and response to splenectomy using information from a large database of patients. Design and Methods Data from 300 consecutive patients with hereditary spherocytosis, grouped according to the results of sodium dodecyl sulphate-polyacrylamide gel electrophoresis, were analyzed and the sensitivity of red cell osmotic fragility tests was compared in various subsets of patients. Results Band 3 and spectrin deficiencies were the most common protein abnormalities (54% and 31%, respectively); 11% of cases were not classified by the electrophoretic analysis. Spectrin deficiency was more frequently diagnosed in childhood and band 3 deficiency in adulthood. Hemoglobin concentration was slightly lower, spherocyte number and hemolysis markers higher in spectrin deficiency than in band 3 deficiency. The sensitivity of the osmotic fragility tests ranged from 48% to 95%, and was independent of the type and amount of the membrane defect. The association of the acidified glycerol lysis test and the NaCl test on incubated blood reached a sensitivity of 99%. Splenectomy corrected the anemia in patients with all subtypes of hereditary spherocytosis although spectrin-deficient patients still showed increased reticulocyte numbers and levels of unconjugated bilirubin. Splenectomy allowed the identification of the membrane defect in all the previously unclassified patients, most of whom had spectrin and/or ankyrin deficiency. Conclusions The definition of the red cell membrane defect in hereditary spherocytosis has no major clinical implications, but may be useful for a differential diagnosis from other hematologic disorders that mimic this hemolytic anemia.

Clinical heterogeneity and predictors of outcome in primary autoimmune hemolytic anemia: a GIMEMA study of 308 patients

The clinical outcome, response to treatment, and occurrence of acute complications were retrospectively investigated in 308 primary autoimmune hemolytic anemia (AIHA) cases and correlated with serological characteristics and severity of anemia at onset. Patients had been followed up for a median of 33 months (range 12-372); 60% were warm AIHA, 27% cold hemagglutinin disease, 8% mixed, and 5% atypical (mostly direct antiglobulin test negative). The latter 2 categories more frequently showed a severe onset (hemoglobin [Hb] levels ≤6 g/dL) along with reticulocytopenia. The majority of warm AIHA patients received first-line steroid therapy only, whereas patients with mixed and atypical forms were more frequently treated with 2 or more therapy lines, including splenectomy, immunosuppressants, and rituximab. The cumulative incidence of relapse was increased in more severe cases (hazard ratio 3.08; 95% confidence interval, 1.44-6.57 for Hb ≤6 g/dL; P < .001). Thrombotic events were associated with Hb levels ≤6 g/dL at onset, intravascular hemolysis, and previous splenectomy. Predictors of a fatal outcome were severe infections, particularly in splenectomized cases, acute renal failure, Evans syndrome, and multitreatment (4 or more lines). The identification of severe and potentially fatal AIHA in a largely heterogeneous disease requires particular experienced attention by clinicians.

Polymorphism of the complement receptor 1 gene correlates with the hematologic response to eculizumab in patients with paroxysmal nocturnal hemoglobinuria

Complement blockade by eculizumab is clinically effective in hemolytic paroxysmal nocturnal hemoglobinuria. However, the response is variable and some patients remain dependent on red blood cell transfusions. In 72 patients with hemolytic paroxysmal nocturnal hemoglobinuria on eculizumab we tested the hypothesis that response may depend on genetic polymorphisms of complement-related genes. We found no correlation between the complement component C3 genotypes and the need for blood transfusions. On the other hand, we found a significant correlation with the HindIII polymorphism of a complement regulatory gene, the complement receptor 1 (CR1) gene. At this locus two co-dominant alleles are known, of which H (common) is associated with high expression, whereas L (rare) is associated with low expression of CR1 on red blood cells. Patients who still needed blood transfusion on eculizumab accounted for 18% of the H/H homozygotes, 33% of the H/L heterozygotes and 68% of the L/L homozygotes (P=0.016). Thus, patients with paroxysmal nocturnal hemoglobinuria who have the L/L genotype are seven times more likely to be sub-optimal responders to eculizumab. Both in vitro and in vivo we found that the CR1 HindIII genotype correlates with the abundance of paroxysmal nocturnal hemoglobinuria red cells that have bound C3, and with the kinetics of C3 binding. These results are consistent with the notion that by affecting C3 binding the CR1 genotype influences the response to eculizumab treatment, and this emerges as a novel example of pharmacogenetics.

Response to vincristine treatment in a case of idiopathic hypereosinophilic syndrome with multiple clinical manifestations.

A case is reported of idiopathic hypereosinophilic syndrome involving many organs and systems and with a wide range of clinical findings: hematologic, cardiovascular, skin, pulmonary, spleen, liver, and gastrointestinal. Mortality in such patients is very high, but aggressive medical treatment (vincristine 2 mg/week for 5 weeks) produced a significant clinical benefit and considerably improved our patients prognosis.

Molecular characterization of the PK-LR gene in sixteen pyruvate kinase-deficient patients

We studied the PK‐LR gene in 16 unrelated patients with congenital haemolytic anaemia associated with erythrocyte pyruvate kinase deficiency. Fifteen different mutations were detected among the 28 mutated alleles identified: two deletions (del 1010G, del 1042–1044); one four nucleotide duplication (nt 1515–1518, GGTC); one splice site [IVS6(−2)t]; nine missense (991A, 1003A, 1151T, 1160G, 1181T, 1181A, 1456T, 1483A, 1529A); and two nonsense (721T, 1675T) mutations. Eight of them [del 1010G, del 1042–1044, dupl 1515–1518, IVS6(−2)t, 1003A, 1160G, 1181T, 1181A] were novel. The deletion 1042–1044 causes the loss of Lys 348. Deletion 1010G and duplication 1515–1518 determine a frameshift and the creation of a stop codon at nucleotides 1019 and 1554 respectively. Mutation IVS6(−2)t leads to an alteration of the 5′ and 3′ splice site consensus sequence; the cDNA analysis shows a 67‐bp deletion in the first part of exon 11 (del 1437–1503). All the four new missense mutations involve highly conserved amino acids. The most frequent mutation in Italy would appear to be 1456T. Correlation was made between mutations, biochemical characteristics of the enzyme and clinical course of the disease.

Treatment of chronic disseminated Geotrichum capitatum infection with high cumulative dose of colloidal amphotericin B and itraconazole in a leukaemia patient

Summary. A case of disseminated granulomatous Geotrichum capitatum infection is reported. A young patient with blastic crisis of chronic myelogenous leukaemia developed septicaemia caused by G. capitatum in the post‐chemotherapy aplastic phase. Subsequently, disseminated infection of the liver, spleen, pancreas and kidneys was observed. Treatment with high cumulative doses of a lipid formulation of amphotericin B (Amphocil®, 20.2 g in 11 weeks) and maintenance with itraconazole resolved clinical manifestations of G. capitatum granulomatous disseminated disease and controlled reactivation of the infection during the two subsequent courses of cytotoxic chemotherapy.

Alpha-2-antiplasmin in acute nonlymphoblastic leukemia

The levels of alpha-2-antiplasmin (alpha 2-AP), antithrombin III (At III) and plasminogen were studied in 21 patients with acute nonlymphoblastic leukemia (ANLL) before and after induction chemotherapy and during bone marrow cellularity recovery after the postchemotherapy aplastic phase. In the patients with M2, M3 or M4 leukemia who had clinical and laboratory evidence of DIC, the alpha 2-AP levels were very low in the initial phase of the disease but improved significantly during recovery of marrow cellularity. At III and plasminogen values were in the normal range at disease onset and showed no significant modification during the course of leukemia. Proteolytic cleavage of alpha 2-AP by granulocyte proteases, rather than hyperfibrinolysis, may be responsible for the low levels of the inhibitor in the proliferative phase of ANLL. This alpha 2-AP deficiency may well contribute to hemorrhagic diathesis in ANLL independently of the presence or absence of hyperfibrinolysis or DIC. Moreover, the lower alpha 2-AP levels observed during the proliferative phase of ANLL may relate to disease activity.

A Controlled Study of the Effect of Sulfinpyrazone on Platelet Survival and on Platelet-Bound 14C-Serotonin Release in Patients with Previous Myocardial Infarction

Preliminary data obtained in the ambit of Anturan Reinfarction Italian Study (ARIS) show that, in postmyocardial infarction, reduced platelet survival time occurred in hyperbetalipoproteinemic patients treated with placebo, but not in the group of patients treated with sulfinpyrazone (interaction between treatment and lipemic level is at p approximately equal to 0.1). The sulfinpyrazone effect on platelet survival is probably related to the release reaction inhibition as suggested by our ex vivo results on platelet-bound 14C-serotonin release.