What do white blood cells do in the immune system and how are they related to exocytosis?

Answer:White Blood Cells protect the body from diseases and foreign invaders. Food is degraded, its nutrients are absorbed by the cell and its waste products are left in the digestive vacuole, which may then leave the cell by exocytosis. Phagocytosis occurs in the scavenging white blood cells of our body. They prowl around looking for invading bacteria and viruses which they engulf and destroy.