Immunsystem: Ein Arzt tastet mit seinen Händen die Halslymphknoten einer Frau ab. Die Frau schaut dabei nach oben und wirkt angespannt.

Immune system

The immune system protects the body from diseases by combating hazardous substances and pathogens. However, this complex system is far from immune to disorders of its own. Both depressed and overactive immune responses can make people ill, for example by causing autoimmune diseases. Inappropriate immune responses can also cause allergies.