Immune System

5. A blood cell that helps protect the body against infection and disease.
7. A long-lasting immune cell that helps the body respond faster to a previously encountered antigen.
9. The body's ability to resist or fight infection and disease.
10. The protection the body develops after exposure to a specific pathogen or antigen.
11. Soft tissue inside bones where blood cells are produced.
15. A protein made by the immune system that recognizes and binds to a specific antigen.
17. A protective response that can cause redness, heat, swelling, and pain.
20. A microorganism or other agent that can cause disease.

1. A type of lymphocyte that helps coordinate immune responses or destroy infected cells.
2. A type of lymphocyte that can produce antibodies.
3. A type of white blood cell that plays an important role in immune defense.
4. A signaling protein that helps immune cells communicate with one another.
6. The body's reaction to pathogens or other harmful substances.
8. A clear fluid that travels through the lymphatic system and carries immune cells.
12. A substance that triggers an immune response in the body.
13. An immune cell that surrounds and engulfs pathogens or other foreign material.
14. A small structure that filters lymph and helps the body fight infection.
16. The body's natural, immediate defense against many types of pathogens.
18. A large immune cell that surrounds and digests pathogens and damaged cells.
19. An organ that filters blood and helps the immune system respond to infection.