Research Units are designed to provide clear summaries of results and impacts of research conducted at Canadian Blood Services. Written by Canadian Blood Services researchers in collaboration with the knowledge mobilization team, these summaries will help in further disseminating research findings to facilitate informed decision-making.
The immune system fights infection by identifying and destroying foreign material such as viruses and bacteria. Antibodies recognize these “invaders” through interactions with molecules called antigens on the surface of the virus or bacteria. Human cells also have antigens; for example, antigens on red blood cells determine blood types (ABO and Rh factor). If someone with type A blood receives a transfusion of type B blood, their antibodies will attack the unfamiliar “B” antigens on the red blood cells, causing a dangerous transfusion reaction.
Serious adverse reactions to incompatible blood are caused by antibody–antigen interactions: if the recipient’s antibodies recognize an antigen on the surface of transfused blood cells, they bind to the antigen, which flags the blood cells for destruction by the recipient’s immune cells and can cause illness due to severe anemia. Similar reactions can occur in patients receiving other blood products, such as the plasma-derived drug intravenous immunoglobulin (IVIG).
Red blood cell transfusions are the most common procedure in contemporary medicine, and are used to treat a wide variety of conditions from anaemia to massive blood loss after trauma. There are many guidelines on when to give a red blood cell transfusion, but less is known about whether differences in red blood cell donors affect the outcomes of transfusion recipients. Although the donation and red blood cell preparation processes are standardized, there are inherent differences in every red blood cell unit because they come from unique, individual donors
Over 50 years ago, plastic replaced glass as the container of choice for collection and storage of blood and blood products. This greatly improved the safety of blood for transfusion by reducing the risk of contamination and containers breaking. Polyvinylchloride, better known as PVC, is the most popular plastic for blood bags because it is durable, strong and can resist temperature changes. However, PVC is inflexible and brittle. To make flexible bags suitable for blood storage, PVC must be combined with a chemical called a “plasticizer”, which softens the plastic.
There is no question that blood transfusions save lives. Whether some blood products lead to better patient outcomes than others, however, has been up for much discussion. For the past 15 years, the biggest question has been: Does transfusing “older” red blood cells (i.e. those that have been stored longer before transfusion) lead to worse patient outcomes? The results of more than 50 observational studies investigating this question were contradictory, but recent clinical studies show no evidence of worse outcomes when older red blood cells are transfused.
Dengue is the most common virus spread by insects. Typically transmitted through the bite of Aedes mosquitoes (like its close cousins West Nile virus and Zika virus), symptoms range from mild flu-like symptoms to, in rare cases, severe hemorrhagic fever, which can be fatal. The global burden of dengue virus is considerable: Approximately 2.5 billion people are at risk and almost 400 million people are infected every year — about 25,000 die. Although mostly in tropical and subtropical regions, travel and increasing globalization means dengue can be found worldwide. Like all viruses, dengue needs another living organism — a host — in order to reproduce and survive. Viruses enter the host’s cells and use the cell’s internal machinery to replicate their own genetic material (in the case of dengue, singlestranded RNA).
Canadian Blood Services’ researchers have made significant advances toward developing a new therapy for a bleeding disorder. Immune thrombocytopenia (ITP) is an autoimmune disease in which the body generates antibodies against its own blood platelets leading to platelet destruction. Platelets are important cells in the bloodstream that form clots to stop bleeding. When platelets are destroyed, bruising and bleeding can readily occur. A drug called IVIG can be used to treat ITP.
However, IVIG is derived from human plasma, is costly and alternative therapies are needed. In ITP, autoimmune antibodies bind to platelets and trigger phagocytosis, a defence mechanism by which an immune cell engulfs or eats another cell to destroy it. Macrophages, the immune cells involved in platelet destruction in ITP, have proteins on their surface called Fc receptors. Using these receptors, macrophages recognize platelets that have antibodies bound to them, then engulf and destroy them.
From the time of donation until transfusion, red blood cells can be stored for up to 42 days. During this time, the cells must be kept alive and functioning. Red blood cells are stored in solutions that contain nutrients and in bags that allow exchange of oxygen and other gasses. The cell’s metabolism – the chemical processes that sustain life – remain active in stored red blood cells. The chemicals that result from metabolism (metabolites), are released by the cells and can build up in the bag over time. These metabolites, and other proteins that are in the bag, are transfused along with the red blood cells
Chances are if you’ve ever given blood then you know your blood type. But why is blood typed and matched before transfusion? What exactly makes blood types different and why is it important? Blood type is based on antigens. Antigens can be proteins, sugars or lipids present on the surface of red blood cells. The body can use antigens as signals to distinguish "self" from "foreign". If incompatible blood is used, that mismatch can sometimes cause an immune response against the transfused red blood cells, destroying them and making the recipient ill. Of more than 30 red blood cell antigen groups, ABO and Rh are the most clinically significant
When the body attacks its own cells, the results can be devastating. Immune thrombocytopenia (ITP) is an autoimmune disease in which the body produces antibodies against blood platelets. These antibodies bind to platelets and tag them, causing them to be recognized as "foreign" by the immune system and destroyed. Platelets work by sticking together and forming a plug that seals broken blood vessels, so the loss of too many platelets can lead to serious bleeding.
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