Baby changed in the hospital? ABO blood type problem and solution

Before the 1900s, it was thought that all blood was the same, a misunderstanding that led to frequently fatal transfusions of animal blood into humans and hazardous transfusions of blood between people. Human blood is not the same—people belong to different blood groups, depending upon the surface markers found on the red blood cell. The cells that make up the body’s tissues and organs are covered with surface markers, or antigens. Red blood cells are no different. This chapter will describe the types of red blood cell antigen and explain why they are so important in medicine today. Antigens stimulate an immune response An antigen is any substance to which the immune system can respond. For example, components of the bacterial cell wall can trigger severe and immediate attacks by neutrophils. If the immune system encounters an antigen that is not found on the body’s own cells, it will launch an attack against that antigen. Conversely, antigens that are found on the body’s own cells are known as “self-antigens“, and the immune system does not normally attack these. The membrane of each red blood cell contains millions of antigens that are ignored by the immune system. However, when patients receive blood transfusions, their immune systems will attack any donor red blood cells that contain antigens that differ from their self-antigens. Therefore, ensuring that the antigens of transfused red blood cells match those of the patient’s red blood cells is essential for a safe blood transfusion. Red blood cell antigens can be sugars or proteins Blood group antigens are either sugars or proteins, and they are attached to various components in the red blood cell membrane. For example, the antigens of the ABO blood group are sugars. They are produced by a series of reactions in which enzymes catalyze the transfer of sugar units. A person’s DNA determines the type of enzymes they have, and, therefore, the type of sugar antigens that end up on their red blood cells. In contrast, the antigens of the Rh blood group are proteins. A person’s DNA holds the information for producing the protein antigens. The RhD gene encodes the D antigen, which is a large protein on the red blood cell membrane. Some people have a version of the gene that does not produce D antigen, and therefore the RhD protein is absent from their red blood cells. Red blood cell membrane and some of the blood group antigens attached to it. Aside from the sugar (glycan or carbohydrate) antigens, the red blood cell membrane contains three types of protein that carry blood group antigens: single-pass proteins, multi-pass proteins, and glycosylphosphatidylinositol (GPI)-linked proteins. Click on the blood groups to find out more about the antigens that define it. Red blood cell antigens determine your blood group The antigens expressed on the red blood cell determine an individual’s blood group. The main two blood groups are called ABO (with blood types A, B, AB, and O) and Rh (with Rh D-positive or Rh D-negative blood types). The functions of many of the blood group antigens are not known, and if they are missing from the red blood cell membrane, there is no ill effect. This suggests that if the blood group antigens used to have a function, e.g., one particular blood group antigen made red blood cells more resistant to invasion from a parasite, it is no longer relevant today. But the presence or absence of red blood cell antigens becomes extremely important when blood from different people mixes, e.g., when a patient receives a blood transfusion from a blood bank. This also happens when a mother becomes pregnant because during labor, a small amount of fetal blood enters her circulation. In these circumstances, exposure to the foreign antigens on the red blood cells can trigger immune reactions. It is not possible to completely remove the danger of adverse reactions when blood from two people mix, but the danger can be minimized. Before a blood transfusion takes place, the blood to be donated must be “typed and cross matched“ with the patient’s blood to ensure immune compatibility. In pregnancy, the risk of the mother’s immune system attacking the foreign antigens present on her fetus’ red blood cells is prevented by giving the mother antibodies to cover fetal red blood cell antigens and removing them from the mother’s circulation before her immune cells find them #GeneticsExamQuestionsSolutions #bloodTransfusions #GeneticsLecture #immuneSystem #RhDProtein #donorRedBloodCells #singlepassProteins #genetics #Genetics101 #multipassProteins #immuneCompatibility #GeneticExamQuestionsSolutions #carbohydrate #molecularBiology #bloodBank #aboBloodGroup #antigens #edBloodCell #RhBloodGroup #glycan #foreignAntigens #glycosylphosphatidylinositol #Cancer #enzymes #DAntigen #gene #NikolaysGeneticsLessons