Cell recognition in the immune system Flashcards
What is an antigen?
Antigens are unique proteins found on the surface of cells
What is the function of antigens?
They allow the immune system to distinguish between self cells and foreign cells
What kind of cells detect foreign antigens?
Lymphocytes
Name the 4 cells / molecules that can be identified by the immune system by their antigens
- Pathogens
- Cells from other organisms of the same species
- Abnormal body cells
- Toxins
What is a pathogen?
A microorganism that causes disease in plants or animals
What are 3 examples of pathogens?
- Bacteria
- Fungi
- Viruses
What is an example of “cells from other organisms of the same species”?
A transplanted organ
- May be rejected due to having foreign antigens
What is an example of abnormal body cells?
Cancer cells
What is a toxin?
Toxins are antigen molecules
What is an example of a toxin?
Some pathogens release toxins into the blood, such as cholera
What is antigen variability?
Pathogens DNA can mutate frequently and if a mutation occurs in the gene which codes for the antigen, the shape of the antigen will change
Why is antigen variability bad?
If the antigens of a pathogen change shape, any previous immunity to this pathogen will no longer be effective as all the memory cells will have a memory of the old antigen shape
