Immune System Say: ih-myoon sis-tum This body system, which includes white blood cells and lymph nodes, helps protect your body from disease. The immune system has different parts, all of which work together to fight off outside invaders like germs. Every day your immune system does battle to keep you healthy and feeling your best. Back to Articles Related Articles Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.