The German word “Kampf” means struggle. Zoologist Elie (or Ilya) Metchnikoff was the first to use Kampf “to encapsulate the relationship between an organism and its invaders” (175). He argued that a struggle occurred between the microbe (invader) and the organism’s white blood cells. Sometimes the invader succeeds in replicating within cells, but typically the white blood cells get to the site of invasion (or injury or inflammation) and consume the invader. By doing so, they help the body build immunity.

Mukherjee uses battles and soldiers to describe how cells defend against infection and inflammation. Neutrophils, a type of short-lived white blood cell, are “hot for combat, their faces granulated, their nuclei dilated—a fleet of teenage soldiers deployed to battle” (175). The release of proteins (cytokines and chemokines) at the site of injury drives the guardian cells (neutrophils) to their mission: to defend the cells against infection and inflammation. Neutrophils inherently recognize some bacteria, so even when microbes aren’t invading cells, they’re still always a part of the human body, further highlighting Kampf.

However, viruses can confuse cells, preventing them from fighting. The COVID-19 pandemic is a poignant example. This virus tricks cells in patients with already compromised antiviral response systems into treating it as nonpathogenic.