Our red blood cells typically last about 110- 120 days. If a red blood cell is damaged or becomes old, it is filtered out and destroyed by the liver and spleen. Damaged or old red blood cells basically get stuck in these organs where macrophages, one of our bodies main immune defense cells, destroy them. Anemia is a disease that occurs if this process occurs too fast and our red blood cells are destroyed faster than our body can make new ones.