ABSTRACT
Two patients with paroxysmal nocturnal hemoglobinuria (PNH) and parvovirus B19 (PVB19) infection are reported. One was infected by PVB19-contaminated blood transfusion, whereas the other had become infected naturally. Both patients completely recovered after transient pancytopenia, but showed severe and intermediate neutropenia (0.216 and 0.768 x 10(9)/l, respectively) at the nadirs of aplastic crises. In the literature, PNH cases also showed neutropenia (0 and 0.54 x 10(9)/l) at aplastic crises. When patients with PNH are infected by PVB19, they may show severe neutropenia and mild thrombocytopenia in addition to severe reticulocytopenia. Therefore, these patients might have to be treated with granulocyte colony-stimulating factor to be able to recover from severe neutropenia.
Subject(s)
Hemoglobinuria, Paroxysmal/complications , Neutropenia/etiology , Parvoviridae Infections/complications , Parvovirus B19, Human , Aged , Female , Granulocyte Colony-Stimulating Factor/therapeutic use , Humans , Male , Middle Aged , Pancytopenia/etiology , Parvoviridae Infections/drug therapy , Parvoviridae Infections/transmission , Transfusion ReactionABSTRACT
We report a family with Bernard-Soulier syndrome with a homozygous mutation within the GPIb(beta) gene. The proband was a 24-year-old Japanese male who has suffered from life-long bleeding tendency. The patient's sister also had severe bleeding episodes. The proband and the affected sister had no apparent complications including organic or skeletal anomaly, or mental disturbance. They had thrombocytopenia [(35-40) x 10(9)/l] with giant platelets. In addition to platelet size, electron microscopic analysis revealed abnormalities in the internal structures of platelets. Ristocetin-induced platelet aggregation was defective. Flow cytometric analysis and western blot analysis showed that glycoprotein IX was nearly absent in platelets, whereas GPIb(alpha) and GPV were detectable. Genetic studies revealed a 13 base pair deletion in the signal peptide-coding sequence of GPIb(beta). The deletion would cause a frame-shift, resulting in the appearance of a stop codon following an indifferent polypeptide sequence. Analysis of platelet RNA showed that the mutant GPIb(beta) gene was transcribed. The propositus and his affected sister were homozygous for the deletion, whereas their unaffected father and mother were heterozygotes. The molecular defects of this family would help understand the relevance of GPIb(beta) for complex formation of the glycoprotein Ib/IX/V receptor.
Subject(s)
Bernard-Soulier Syndrome/genetics , Platelet Glycoprotein GPIb-IX Complex/genetics , Protein Sorting Signals/genetics , Sequence Deletion , Adult , Amino Acid Sequence , Base Sequence , Bernard-Soulier Syndrome/blood , Bernard-Soulier Syndrome/complications , Blood Platelets/metabolism , Blood Platelets/ultrastructure , Codon/genetics , DNA/chemistry , DNA/genetics , DNA Mutational Analysis , Family Health , Female , Flow Cytometry , Hemorrhage/complications , Hemorrhage/genetics , Homozygote , Humans , Immunoblotting , Male , Microscopy, Electron , Molecular Sequence Data , Pedigree , Platelet Glycoprotein GPIb-IX Complex/metabolism , Polymerase Chain Reaction , RNA, Messenger/genetics , RNA, Messenger/metabolism , Repetitive Sequences, Nucleic Acid , Sequence Homology, Amino AcidABSTRACT
OBJECTIVE: The aim of this study was to determine whether granulocytes from patients with paroxysmal nocturnal hemoglobinuria (PNH) are more or less intrinsically sensitive to spontaneous apoptosis than granulocytes from healthy individuals. Resistance to apoptosis has been suggested as an explanation for the proliferation or selection of PNH clones. PATIENTS AND METHODS: Peripheral blood granulocytes from five patients with PNH, five patients with myelodysplastic syndrome (MDS), and five healthy volunteers were cultured in the absence of serum. Spontaneous apoptosis of the granulocytes was assessed every 6 hours by flow cytometry. The expression levels of CD16b, CD95, and granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor also were studied by flow cytometry, and caspase-3 activity was measured by fluorometry. RESULTS: There were no significant differences in the proportion or absolute numbers of apoptotic and apoptotic/dead granulocytes between the cells from PNH patients and healthy individuals, whereas those from MDS patients showed significantly lower frequencies of apoptotic granulocytes compared with normal controls. The proportion of CD16b(-) granulocytes was not significantly different among the three groups during in vitro culture. CD95 and GM-CSF receptor was not significantly increased in cultured granulocytes or noncultured granulocytes from, respectively, patients with PNH and normal controls. Caspase-3 activity significantly decreased in cultured granulocytes from MDS patients, but not in granulocytes from PNH patients. CONCLUSIONS: Granulocytes from PNH patients did not display a reduced sensitivity to spontaneous apoptosis, suggesting that the apoptosis of blood cells in PNH may not be an important factor in proliferation or selection of PNH clones. These findings are in agreement with the normal lifespan of granulocytes in vivo.
