Benchmark 6E
The Human Organism: Physical Health
Grades 6-8, page 145

White blood cells engulf invaders or produce antibodies that attack them or mark them for killing by other white cells. The antibodies produced will remain and can fight off subsequent invaders of the same kind.

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.