Sucrose lysis test is when the patient's serum is mixed in sucrose, which causes hemolysis of PNH cells. Ham's test is when the patient's cells are incubated in acidified serum, which triggers the alternative compliment pathway, resulting in lysis of PNH cells. Positive sucrose lysis test or Ham test (both test sensitivity of RBCs to lysis by complement).Nonvascular causes: prosthetic valve (more common with mechanical, more common at aortic valve), LVAD, TIPS, coil embolization, patched AV shunt, AVM.This hemolysis results from the impaired regulation of the alternative pathway upstream in the complement cascade, as well as of the downstream terminal pathway. Drugs: chemotherapy Clopidogrel (Plavix) associated with TTP The lack of the complement regulators CD55 and CD59 on PNH erythrocytes accounts for the hallmark of PNH, which is the chronic, complement-mediated intravascular hemolysis.Other medical causes: malignancy, renal allograft rejection, vasculitides like polyarteritis nodosa and Wegener's granulomatosis.Paroxysmal nocturnal hemoglobinuria (PNH) The regulatory proteins CD55 and CD59 are glycolsylphosphatidylinositol-anchored, type I cell surface proteins, which inhibit formation of the C3 convertases and prevent the terminal polymerization of the membrane attack complexes, respectively.Thrombotic Thrombocytopenic Purpura (TTP).Disseminated Intravascular Coagulation (DIC).Myelodysplastic syndrome (MDS) or myeloproliferative disordersÄifferential Diagnosis Microangiopathic Hemolytic Anemia (MAHA).Bone marrow failure leading to aplastic anemia.DVT, thrombosis of hepatic/intraabdominal/cerebral veins, arterial thrombosis.Renal failure (both from intravascular hemolysis causing AKI and chronic hemolysis causing iron deposition in kidneys).Nocturnal hemolysis attributed to intestinal absorption of lipopolysaccharide (strong activator of complement) at night.Hemolysis precipitated by stresses that activate complement (eg infection).Abnormal PIG-A gene > defect in GPI-linked anchor > partial/complete absence of GPI-linked proteins (mainly CD55 and CD59) > increased sensitivity of RBCs to hemolytic action of complement.Intravascular hemolysis caused by increased sensitivity of RBCs to hemolytic action of complement.3.1 Microangiopathic Hemolytic Anemia (MAHA).Additional studies are needed to define the role of the deficiencies of CD55 and CD59 in the pathogenesis of autoimmune hemocytopenias. We conclude that the diminished expression of the glycolsylphosphatidylinositol-anchored type I cell surface proteins CD55 and CD59 is not specific to PNH and that it can be found in patients with a variety of autoimmune disorders. In the two patients with ES we did not found changes in the expression of CD55 and CD59. In the patients with AA, a diminished expression in red blood cells was not found however, one patient was found with a diminished expression of CD59 in granulocytes, and one patient with a diminished expression of CD55 in the platelets. In the subset of patients with SLE only one was found with a CD55 diminished expression in the red blood cells. In the patients with ATP one was found with CD55 diminished expression in red blood cells, one with CD59 diminished expression granulocytes and one with a CD59 diminished expression in the platelets. Paroxysmal nocturnal hemoglobinuria (PNH) is a genetic disorder due to the impaired conformation of the glycolsylphosphatidylinositol anchor, which results in the deficient expression of CD55 and CD59 leading to excessive destruction of red cells and leukocytes. In the seven patients with AIHA two were found with CD59 diminished expression in red blood cells and one with CD59 diminished expression in granulocytes. A diminished expression of CD55 and CD59 was found in the three cell lines of the two patients with PNH. We have studied the expression of these two molecules in red blood cells, granulocytes and platelets in patients with PNH (two patients), autoimmune hemolytic anemia (AIHA) (seven patients), autoimmune thrombocytopenia (ATP) (22 patients), systemic lupus erythematosus (SLE) (19 patients), aplastic anemia (AA) (eight patients), and Evans syndrome (ES) (two patients). Paroxysmal nocturnal hemoglobinuria (PNH) is a genetic disorder due to the impaired conformation of the glycolsylphosphatidylinositol anchor, which results in the deficient expression of CD55 and CD59 leading to excessive destruction of red cells and leukocytes. ![]() The regulatory proteins CD55 and CD59 are glycolsylphosphatidylinositol-anchored, type I cell surface proteins, which inhibit formation of the C3 convertases and prevent the terminal polymerization of the membrane attack complexes, respectively.
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