Test 2: Antigens and Antibodies Flashcards
Antigen traits
- Immunogenicity
- Antigenicity
- Allergenicity
- Tolerogenicity
Immunogen traits (antigens that cause an immune response)
- molecular size
- chemical composition and molecular complexity
- Foreignness
- Stimulate B/T cells
- Degradability
Epitope
binding site of antigen, more complex forms attach better
Haptens
cannot stimulate antibody alone but can with a carrier
Autoantigen
antigen from within body
Alloantigen
antigen from same species
Heteroantigen
antigen from different species, can cause uncontrolled immune response
Heterophile antigens
antigen from two different species that have the same function
Adjuvant
substance with immunogen that increases immune response (included in vaccines)
MHC class I on APC
intracellular defense, cancer, viral (antigen already within cell)
MHC class II on APC
bacterial, anything extracellular, exogenous antigen
Isotype heavy chain
same heavy chain for each class of Abs
Allotype heavy chain
variations in constant regions of each class of Abs
Idiotype heavy chain
variations in variable regions that give specificity
IgG characteristics
- monomer
- 80% in serum
- 1/2 life:23 days
- initiates complement
- ONLY ONE that crosses placenta
IgM characteristics
- pentamer
- 5-10% in serum
- 1/2 life: 5 days
- initiates complement
- 1st antibodies during infection
IgA characteristics
-dimer
-10-15% in serum
1/2 life: 6 days
-does not initiate complement
IgD characteristics
-monomer
-.2% in serum
1/2 life: 3days
-present on naive B cells
IgE characteristics
- monomer
- .002% in serum
- 1/2 life: 2 days
- bound to mast cells and basophils
- doesn’t initiate complement
- helps with allergies and parasites
Cross reactivity
one antibody can bind with multiple antigens
Streptococcus pyogenes
cell wall proteins called M antigens–can cross react with myocardial and skeletal muscle proteins
