Concept: Hemolytic anemia
Primaquine is a key drug for malaria elimination. In addition to being the only drug active against the dormant relapsing forms of Plasmodium vivax, primaquine is the sole effective treatment of infectious P. falciparum gametocytes, and may interrupt transmission and help contain the spread of artemisinin resistance. However, primaquine can trigger haemolysis in patients with a deficiency in glucose-6-phosphate dehydrogenase (G6PDd). Poor information is available about the distribution of individuals at risk of primaquine-induced haemolysis. We present a continuous evidence-based prevalence map of G6PDd and estimates of affected populations, together with a national index of relative haemolytic risk.
We sought to evaluate the feasibility and efficacy of hybrid transapical closure of paravalvar mitral leaks using a new Occlutech PLD occluder in patients with heart failure and/or haemolytic anaemia.
The purpose of this study was to evaluate the efficacy of intravenous human immunoglobulin (IVIG) in the presence of high-intensity phototherapy in decreasing the need for exchange transfusion in newborns with rhesus hemolytic disease.
Antibody binding to red blood cells (RBCs) can induce potentially fatal outcomes, including hemolytic transfusion reactions (HTRs), hemolytic disease of the fetus and newborn, and autoimmune hemolytic anemia. The mechanism(s) of RBC destruction following antibody binding is typically thought to require complement activation and/or the involvement of Fcγ receptors (FcγRs). In the current report, we analyzed mechanisms of HTRs during incompatible transfusions of murine RBCs expressing human glycophorin A (hGPA) into mice with anti-hGPA.
Thrombotic microangiopathy (TMA) in patients with sickle cell disease (SCD) is a rare complication. These patients manifest microangiopathic hemolytic anemia (MAHA) with laboratory evidence of hemolytic anemia, schistocytosis, and thrombocytopenia. This is the first report of the syndrome in a group of these patients. A retrospective chart analysis of 10 consecutively diagnosed patients in SCD crisis who were referred for therapeutic plasma exchange (TPE) after developing MAHA was done. Patients had chest pain, respiratory distress, fever, pulmonary infiltrates, jaundice, and neurological dysfunction with abnormal liver function and coagulation tests. MAHA was diagnosed after a median hospital stay of 5 days. Nine patients recovered completely following TPE with fluid replacement by fresh frozen plasma with or without cryo-poor plasma. Incomplete response to TPE in one case was due to the development of fresh complications. During a median follow-up period of 77 months, there was one recurrent episode and one death in SCD crisis but without evidence of MAHA. TMA is not a very rare complication among Bahraini SCD patients in crisis. Characteristic features of this disorder are acute chest syndrome, organ failure, leuco-erythroblastosis, and a combination of thrombocytopenia, LDH level >1,000 U/l, and schistocytes in blood smears. Management with TPE usually leads to complete recovery with little chance of short-term recurrence. Multiple pathogenetic mechanisms leading to increased von Willebrand factor and its multimers may form the basis of this syndrome.
INTRODUCTION: Schistocytes are major signs of micro- and macroangiopathic haemolytic anaemia. The aim was to evaluate automated fragmented red cell (FRC) count compared to visual microscopy, and to assess FRCs in the presence of microcytosis and hypochromia using Sysmex automated counters. METHODS: Schistocytes were determined with visual microscopy after the observation of 1000 erythrocytes, and the automated counting with Sysmex XE-5000. Indices of microcytosis (%MicroR) and hypochromia (%Hypo-He) were also analysed in the XE-5000 analyser. RESULTS: Linear regression analysis showed a good correlation between automated and manual FRC% count (r = 0.824, P < 0.0001), but Bland-Altman's plot revealed an overestimation of FRC of 0.82%. There is a global correlation between %MicroR and FRCs. In subgroup analysis of %MicroR (reference value: 0.3-3%, mild microcytosis: 3.1-7.2% and severe microcytosis: 7.3-56.7%), no correlations with automated %FRC were noticed (P > 0.05). Based on %Hypo-He subgroups (mild hypochromia: 1.2-5.2%, and severe hypochromia: 5.3-35.4%), a significant correlation of automated %FRC with mild hypochromia was found (r = 0.621, P < 0.01). CONCLUSION: Despite the agreement between FRC count and the manual method, the overvaluation of FRC was high, leading to false-positive results. Microcytosis appeared to have no impact on FRC count, whereas mild hypochromia seemed to be related with FRC count. Particular attention is required to assess automated FRCs in samples with mild hypochromia.
Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by complement-mediated intravascular hemolysis because of the lack from erythrocyte surface of the complement regulators CD55 and CD59, with subsequent uncontrolled continuous spontaneous activation of the complement alternative pathway (CAP), and at times of the complement classic pathway. Here we investigate in an in vitro model the effect on PNH erythrocytes of a novel therapeutic strategy for membrane-targeted delivery of a CAP inhibitor. TT30 is a 65 kDa recombinant human fusion protein consisting of the iC3b/C3d-binding region of complement receptor 2 (CR2) and the inhibitory domain of the CAP regulator factor H (fH). TT30 completely inhibits in a dose-dependent manner hemolysis of PNH erythrocytes in a modified extended acidified serum assay, and also prevents C3 fragment deposition on surviving PNH erythrocytes. The efficacy of TT30 derives from its direct binding to PNH erythrocytes; if binding to the erythrocytes is disrupted, only partial inhibition of hemolysis is mediated by TT30 in solution, which is similar to that produced by the fH moiety of TT30 alone, or by intact human fH. TT30 is a membrane-targeted selective CAP inhibitor that may prevent both intravascular and C3-mediated extravascular hemolysis of PNH erythrocytes and warrants consideration for the treatment of PNH patients.
A 9-month-old boy with life-threatening multiresistant pure red cell anemia/autoimmune hemolytic anemia within the frame of a possible, undiagnosed immune-mediated disease was initially treated with prednisone. Further-line therapies of the following 7 relapses included immunoglobulins, rituximab, cyclophosphamide, and alentuzumab followed by other maintenance treatments as cyclosporine, methotrexate, and mycophenolate. After all the administered therapies failed, the patient was successfully treated by splenectomy followed by fludarabine and then sirolimus as maintenance treatment. Relapses might have been caused by the lack of a complete debulking of triggering cells and/or ineffective maintenance therapy. Splenectomy and sirolimus may have played a complementary role in the management of both situations.
This study was performed to explore other potential mechanisms underlying hemolysis in addition to pore-formation of tentacle extract (TE) from the jellyfish Cyanea capillata. A dose-dependent increase of hemolysis was observed in rat erythrocyte suspensions and the hemolytic activity of TE was enhanced in the presence of Ca2+, which was attenuated by Ca2+ channel blockers (Diltiazem, Verapamil and Nifedipine). Direct intracellular Ca2+ increase was observed after TE treatment by confocal laser scanning microscopy, and the Ca2+ increase could be depressed by Diltiazem. The osmotic protectant polyethylenglycol (PEG) significantly blocked hemolysis with a molecular mass exceeding 4000 Da. These results support a pore-forming mechanism of TE in the erythrocyte membrane, which is consistent with previous studies by us and other groups. The concentration of malondialdehyde (MDA), an important marker of lipid peroxidation, increased dose-dependently in rat erythrocytes after TE treatment, while in vitro hemolysis of TE was inhibited by the antioxidants ascorbic acid-Vitamin C (Vc)-and reduced glutathione (GSH). Furthermore, in vivo hemolysis and electrolyte change after TE administration could be partly recovered by Vc. These results indicate that lipid peroxidation is another potential mechanism besides pore-formation underlying the hemolysis of TE, and both Ca2+ channel blockers and antioxidants could be useful candidates against the hemolytic activity of jellyfish venoms.
During exercise the cardiovascular system has to warrant substrate supply to working muscle. The main function of red blood cells in exercise is the transport of O2 from the lungs to the tissues and the delivery of metabolically produced CO2 to the lungs for expiration. Hemoglobin also contributes to the blood’s buffering capacity, and ATP and NO release from red blood cells contributes to vasodilation and improved blood flow to working muscle. These functions require adequate amounts of red blood cells in circulation. Trained athletes, particularly in endurance sports, have a decreased hematocrit, which is sometimes called “sports anemia.” This is not anemia in a clinical sense, because athletes have in fact an increased total mass of red blood cells and hemoglobin in circulation relative to sedentary individuals. The slight decrease in hematocrit by training is brought about by an increased plasma volume (PV). The mechanisms that increase total red blood cell mass by training are not understood fully. Despite stimulated erythropoiesis, exercise can decrease the red blood cell mass by intravascular hemolysis mainly of senescent red blood cells, which is caused by mechanical rupture when red blood cells pass through capillaries in contracting muscles, and by compression of red cells e.g., in foot soles during running or in hand palms in weightlifters. Together, these adjustments cause a decrease in the average age of the population of circulating red blood cells in trained athletes. These younger red cells are characterized by improved oxygen release and deformability, both of which also improve tissue oxygen supply during exercise.