Final answer:
The immune system exhibits immune tolerance to its own erythrocyte antigens but not to foreign erythrocyte antigens.
Step-by-step explanation:
This means that the immune system recognizes and tolerates the antigens present on its own red blood cells (erythrocytes), while mounting an immune response against foreign erythrocyte antigens. Here's why:
1. Self-tolerance: The immune system develops a mechanism called self-tolerance, which allows it to recognize its own cells and molecules as "self" and not mount an immune response against them. This self-recognition helps prevent the immune system from attacking the body's own tissues. In the case of erythrocyte antigens, the immune system is tolerant to the antigens present on its own red blood cells.
2. Foreign antigens: When the immune system encounters foreign substances or antigens, such as those found on foreign red blood cells, it recognizes them as non-self or foreign. This triggers an immune response, leading to the production of antibodies or activation of immune cells to eliminate the foreign antigens. The immune response against foreign erythrocyte antigens is important for protection against pathogens or incompatible blood transfusions.
3. Importance in blood transfusions: The immune system's ability to distinguish self from non-self erythrocyte antigens is crucial in blood transfusions. If someone receives a blood transfusion with erythrocytes carrying antigens that their immune system recognizes as foreign, it can lead to an immune reaction known as a transfusion reaction. This reaction can cause symptoms ranging from mild discomfort to severe complications. Blood typing and cross-matching are performed prior to transfusions to ensure compatibility and prevent adverse immune reactions.