Comparative proteomics of erythrocyte aging in vivo and in vitro.

During aging in vivo and in vitro, erythrocytes display removal signals. Phagocytosis is triggered by binding of autologous IgG to a senescent cell antigen originating on band 3. Erythrocytes generate vesicles as an integral part of the aging process in vivo and in vitro, i.e. during storage. These vesicles display senescent cell antigens as well as phosphatidylserine, that is recognized by scavenger receptors. Recent comparative proteomic analyses of erythrocytes and their vesicles support the hypothesis that aging is accompanied by increased binding of modified hemoglobins to band 3, disruption of the band 3-mediated anchorage of the cytoskeleton to the lipid bilayer, vesicle formation, and antigenic changes in band 3 conformation. Proteomic data also suggest an, until then unknown, involvement of chaperones, stress proteins, and proteasomes. Thus, the presently available comparative proteomic analyses not only confirm previous immunochemical and functional data, but also (1) provide new clues to the mechanisms that maintain erythrocyte homeostasis; (2) open new roads to elucidate the processes that regulate physiological erythrocyte aging and removal, and thereby; (3) provide the foundation for rational interventions to prevent untimely erythrocyte removal, and unwanted interactions between the erythrocyte and the immune system, especially after transfusion.

Fetal/neonatal allo-immune thrombocytopenia (FNAIT): past, present, and future.

UNLABELLED: We reviewed the English, American, and German literature for articles describing the prevalence, clinical presentation, outcome, therapeutic options, and screening possibilities for fetal/neonatal allo-immune thrombocytopenia (FNAIT), published between January 1950 and March 2007. The reported prevalence of FNAIT in human platelet antigen (HPA)-1a-negative women varies between 1/600 to 1/5000 live births among various populations. The typical picture is that of a neonate presenting with purpura minutes to hours after birth, born to a healthy mother with no history of infection or abnormal bleeding, after an uneventful pregnancy with a normal maternal platelet count. Thrombocytopenia in FNAIT can be severe, with intracranial hemorrhage occurring in 10% to 30% of severe FNAIT cases. Several types of neonatal treatment have been proposed, of which transfusion of HPA-compatible platelets is most effective. Antenatal management of FNAIT consists of weekly maternal intravenous immunoglobulin (IVIG) infusions, with or without oral steroid therapy. Serial fetal platelet transfusions can be provided in cases of failure of IVIG therapy, but the multiple cordocenteses that would be required to administer the platelets entail substantial risk. The possibilities for antenatal screening of first pregnancies are limited. Postnatal screening does not prevent neonatal morbidity and mortality. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians. LEARNING OBJECTIVES: After completion of this article, the reader should be able to summarize the many and varied causes of neonatal thrombocytopenia, explain that fetal/neonatal allo-immune thrombocytopenia (FNAIT) is a rare but devastating cause with potential high risk of recurrence, and recall the treatment options for FNAIT as well as their potential side effects.

Erythrocyte ageing in vivo and in vitro: structural aspects and implications for transfusion.

Erythrocyte transfusion is essential in conditions of large blood loss, of inadequate bone marrow production and of increased erythrocyte breakdown. The structural and biochemical changes that erythrocytes go through during storage, probably associated with the disappearance of up to 30% of the erythrocytes within 24 h after transfusion, are likely to contribute to the transfusion side effects: iron overload, erythrocyte adhesion to the endothelial surface with proinflammatory consequences, autoantibody formation, endothelial damage by released erythrocyte constituents, a hampered microcirculation and oxygen delivery. In vivo, senescent erythrocytes are marked for removal by binding of autologous immunoglobulin G to ageing antigens, which arise by changes in the conformation of the membrane domain of band 3. Also, vesicle formation has been described as an integral part of the erythrocyte ageing process. Comparable changes occur during erythrocyte storage. This review describes the current state of knowledge of the mechanism of erythrocyte ageing in vivo, ageing-related changes occurring during erythrocyte storage in blood bank conditions and their possible relation with the transfusion side effects. In view of the key position of band 3 in the maintenance of erythrocyte structure and function, elucidation of the pathways that control posttranslational modification of band 3 during storage may lead to new approaches towards maintaining ATP concentration and cellular integrity. This review concludes with the challenge to further explore the underlying processes of erythrocyte ageing in order to provide physiologically relevant tools for assessing and predicting erythrocyte homeostasis in vitro and in vivo and thereby to contribute to the development of rational transfusion protocols for various patient categories.

Red cell transfusion in medicine: future challenges.

Many side-effects of red blood cell transfusion have been described. They include iron-overload, as well as allo- and autoantibody formation against red cells. During storage, erythrocytes undergo complex structural and biochemical changes. It has been suggested that accelerated and/or aberrant forms of the physiological erythrocyte aging process underlie the red cell storage lesion. This storage lesion may contribute to side-effects of transfusion as endothelial damage by release of internal erythrocyte constituents, (pro)inflammatory consequences, hampered microcirculation and oxygen delivery. Understanding the process that determines the fate of red blood cells after transfusion may contribute to the prevention of side-effects after red blood cell transfusion. This should be the focus of research on red blood cell transfusion in clinical transfusion medicine.

An unusual presentation and way to diagnose hepatocellular carcinoma.

A 67-year-old man with a history of chronic obstructive pulmonary disease (COPD) was admitted with acute progression of dyspnoea, productive cough, fever, elevated central venous pressure, oedema and liver enzyme abnormalities. Pneumonia with secondary right-sided congestive heart failure was considered. Additional abdominal ultrasound examination confirmed by a CT scan showed a mass in the inferior vena cava (VCI) extending into the right atrium. The central liver location and impaired haemostasis rendered liver biopsy impossible. An alternative approach was discussed and guided by two-dimensional transoesophageal electrocardiography accessing the right internal jugular vein, biopsies were taken from the atrial mass with histology suggesting the presence of a hepatocellular carcinoma as the cause of acute dyspnoea.