2.  _____________________________ are things that cause diseases.

3. _________ help memory B cells to develop so that the body remembers how to fight off infections in the future.

4.  Vaccines aren’t effective against __________________________ (like the common cold).

5. In an allergic reaction, you release _____________________, which cause capillaries to swell and release fluid.

6. HIV destroys __________________________, resulting in AIDS.

7. ______________________ are molecules that trigger a defensive response in your system.

8. _____________________ stick to macrophages that display the antigen s from pathogens they have consumed.

9. __________________________ on red blood cells account for the different blood types.

10. ________________________ involves a series of events designed to fight off an infection.

11. The immune response involves 2 kinds of white blood cells: _________________________. 

12. _______________________ on cells allow macrophages to recognize pathogens and other foreign substances.

13. Macrophages engulf and consume invading _________ (recognized as foreign because of their marker proteins).

14. ___________________  (also called phagocytes) play an important role in destroying pathogens and dead cells.

15. A mass of cancerous cells is called a __________________________.

16. HIV is transmitted __________________________.

17. The _______________ acts as both a physical and chemical barrier to prevent pathogens from entering the body.

18. An _____________ involves the response of the immune system to a harmless (to the average person) antigen.

19. _____________ destroy pathogens by pinching holes in their cell membranes.

20. ______________________ stop the immune response once the pathogens have been destroyed.

21. B cells produce _________________ that tie up the pathogens so the macrophages can easily destroy them.

22. _____________________ stay around after the pathogens are destroyed, in case they are needed again.

23. ___________________ is an example of an autoimmune diseases.

24. __________________________ result when the immune system starts to attack its own body cells.

25. ESSAY: What is a carcinogen?