| A | B |
|---|
| Alloantigens | cell surface markers that occur in some members of the same species but not in others |
| Superantigens | potent T cell stimulators; provoke an overwhelming response |
| Allergen | antigen that evokes allergic reactions |
| Autoantigen | molecules on self tissues for which tolerance is inadequate |
| Active immunity | person is challenged with antigen that stimulates production of antibodies; creates memory, takes time, and is lasting |
| Passive immunity | – preformed antibodies are donated to an individual; does not create memory, acts immediately, and is short term |
| Natural immunity | – acquired as part of normal life experiences |
| Artificial immunity | – acquired through a medical procedure such as a vaccine |
| Artificial active immunity | deliberately exposing a person to material that is antigenic but not pathogenic |
| herd immunity | Immune individuals will not harbor it, reducing the occurrence of pathogens --Less likely that a nonimmunized person will encounter the pathogen |
