In 2016, Blood Research Institute Senior Investigator and Senior Director of Immunohematology and Innovation Gregory Denomme, Ph.D., FCSMLS(D), was awarded a grant from the Commonwealth Transfusion Foundation to study immune mediated hemolysis (or, the immune system’s destruction of a patient’s red blood cells) and better understand why some patients have a severely negative reaction to mismatched blood. More specifically, when those patients are transfused with platelets or plasma of a different blood type.
Most people have heard of the major blood types: A positive and A negative; B positive and B negative; AB positive and AB negative; and O positive and O negative. If you really know your stuff, you know that O negative donors have the universal type, meaning their blood can be used to help every single patient, regardless of that patient’s blood type. But the intricacies of blood types go far beyond that.
As we grow, we develop antibodies that help our immune system fight threats to our health. We also create antibodies to diseases like the measles and tuberculosis through vaccination. Depending on our blood type, our bodies also come with (or even without) some ready-made antibodies called anti-A and anti-B. People with an A blood type have anti-B, or the absence of any traces of blood group B. Blood group B has anti-A; blood group AB has neither anti-A nor anti-B, as it has both A and B in its blood type; and blood group O has both anti-A and anti-B (because it is devoid of both A and B). Ideally, physicians want to match blood products to a patient’s blood type; if the incorrect type is given, it can cause an adverse effect called hemolysis, which is when the patient’s immune system destroys its own red cells because it doesn’t recognize the “new” blood.
Dr. Denomme, who came to the Blood Research Institute 10 years ago after a tenure as an assistant professor at the University of Toronto, has a strong background in clinical research. Since arriving, he developed the red cell genotyping program for blood donors, which helps match their blood with patients who have rare blood types. Now the senior director of blood laboratories, Dr. Denomme oversees the Immunohematology Reference Lab, which ensures patients get the right kind of blood they need so that they don’t experience a bad reaction. Because of his wealth of knowledge and experience, Dr. Denomme is perfectly positioned to conduct this research and make a positive impact on patient health.
“I see clinical problems but, because of my background, I can go to the research bench and create solutions that come back to the clinical lab,” he said.
So, what causes some patients to have an adverse reaction to a mismatched blood transfusion? After type O blood is donated, it undergoes a process to remove anti-A and anti-B. When an A, B or AB patient receives an O blood transfusion, a small amount of O plasma is also transfused. Most patients do not experience a negative reaction to this plasma; however, 2-5% experience immune mediated hemolysis, which causes the patient’s red cells to be destroyed.
Dr. Denomme said that sometimes, when a patient receives an incompatible blood transfusion and seems to have hemolysis, the test for it comes back negative. This is because the red cells have been destroyed – there is literally none left to indicate a positive result. A better understanding of what causes immune mediated hemolysis will make it easier to recommend treatment and testing options for patients.
“It’s trying to understand the basic science of why it happens, and bring it back to the clinic,” Dr. Denomme said.
Learn more about Dr. Denomme’s research findings in the article “Potential impact of complement regulator deficiencies on hemolytic reactions due to minor ABO-mismatched transfusions,” published in Blood Advances.
About the expert: Gregory Denomme, Ph.D., FCSMLS(D), is a senior investigator at the Blood Research Institute and senior director of Immunohematology and Innovation. Learn more about Dr. Denomme.