Benchmark 6C
The Human Organism: Basic Functions
Grades 9-12, page 138

The immune system is designed to protect against microscopic organisms and foreign substances that enter from outside the body and against some cancer cells that arise within.

NSES Content Standard C 
Life Science: Structure and function in living systems 
Grades 5-8, page 156 
The human organism has systems for digestion, respiration, reproduction, circulation, excretion, movement, control and coordination, and for protection from disease. These systems interact with one another.