Leukocytes engulf and kill pathogens such as bacteria, fungi, and viruses, and worn-out and cancerous body cells.

Leukocytes

White blood cells, which are part of the immune system, involved in protecting the body against both infectious disease and foreign invaders.

Pathogens

Microorganisms that cause diseases in their hosts, including viruses, bacteria, fungi, and parasites.

Engulf

To surround or cover completely, often used metaphorically to describe overwhelming emotions or situations.