What happens when incompatible RBCs is transfused?

➢ Among the 19 different human blood group systems, the group ABO is the most important. ➢ Nearly all individuals make IgM antibodies to the antigens of the ABO system that they lack ➢ These antibodies do not cross the placenta; they occur naturally, without prior immunization ➢ If an individual is blood group A, he or she will be tolerant to A and agglutinate B red cells, and vice versa for a blood group B individual. ➢ Conversely, a blood group O person will make anti-A and anti-B as natural antibodies and will only tolerate blood transfusions from group O individuals ➢ When planning a blood transfusion, it is important to ensure that donor and recipient blood types are compatible with respect to these major blood groups, otherwise transfusion reactions will occur