What is the structure and importance of leukocytes in the human body?

Leukocytes have a colorless cytoplasm, nucleus and various organelles. Leukocytes are found in the blood, and they provide protection for the body. They are capable of attacking various viruses and foreign objects. The ability of white blood cells to attack certain viruses is called immunity. Therefore, in order for white blood cells to attack viruses and know how to fight them, you need to be vaccinated. Also, you can not limit yourself from various viruses. Viruses and bacilli must attack our body, as it will be ready to fight against strong threats.