Antigens and Antibodies Flashcards
(32 cards)
Foreign molecule that generates an immune response; Any foreign molecular structure recognized by lymphocytes or antibodies
Antigen
Ability of a molecule to be recognized by an antibody or lymphocyte
Antigenicity
Major surface components recognized by the immune system
Bacterial antigens
Not all antigens have high antigenicity; lipopolysaccharides (LPS) in Gram-negative bacteria are highly antigenic. True or False?
True
Bacterial antigens (6)
- Cell wall
- Capsule (K antigen)
- Pili/Fimbriae (F antigen)
- Flagella (H antigen)
- Porins
- Exotoxins
Bacterial proteins that are immunogenic and can be modified into safer forms; Toxins that stimulate antibody (antitoxin) production; can become toxoids when treated with formaldehyde
Exotoxins
Molecules that trigger an immune response during viral infection; Capsid proteins and viral proteins presented on infected cells
Viral antigens
What is the MOA of viruses—a 7-step life cycle inside host cells?
1.) entry
2.) attachment
3.) uncoating
4.) nucleic acid release
5.) protein synthesis
6.) assembly
7.) release
What are non-microbial antigens—foreign molecules from non-pathogenic sources that can trigger allergic reactions? (4)
1.) foods
2.) dust
3.) pollen
4.) venoms
What makes a good antigen—molecular features that enhance immune recognition? (7)
- size
- complexity
- dose
- route
- host genetics
- chemical stability
- foreignness
Sites on the surface of an antigen that stimulates a specific immune response
Epitopes
Small molecules that are non-immunogenic unless bound to carriers; like penicillin or urushiol (poison ivy resin) that only trigger a response when attached to proteins
Haptens
Instances that identical or similar epitopes found on apparently unrelated molecules; Antibodies directed against 1 antigen may react unexpectedly with unrelated antigen; Antibodies directed against protein in 1
sp. may also react in a detectable manner w/ homologous or similar protein in another sp.
Cross-reactivity
Glycoproteins secreted by plasma cells to bind antigens, also called immunoglobulins, they neutralize antigens and activate immune mechanisms
Antibodies
What is the structure of an antibody?
- Y-shaped molecule w/ specific binding sites
- 2 heavy chains
- 2 light chains
- variable (Fab) regions
- constant (Fc) regions
What is the main function of antibodies—their role in adaptive immunity? (4)
- bind antigens
- neutralize toxins/viruses
- activate complement
- aid phagocytosis.
Most abundant antibody in serum and main secondary response antibody; smallest Ig; secreted by plasma cells in spleen, lymph nodes, and bone marrow
IgG
Antibody dominant on mucosal surfaces and in secretions; prevents microbial adherence; found in gut, respiratory, urinary tracts, and milk
IgA
Primary antibody produced during initial immune response; large (pentamer); highly effective in complement activation and agglutination
IgM
Antibody involved in parasite defense and allergic responses; found on mast cells and basophils; triggers inflammation, has shortest half-life
IgE
low-concentration antibody found in some mammals; present in trace amounts; absent in horses, rabbits, and chickens
IgD
Variations in immunoglobulin genes between individuals of the same species; genetic differences in heavy chain genes causing antibody diversity
Allotypes
Variations in variable regions affecting antigen binding; determine antibody specificity via amino acid differences
Idiotypes
Antibodies from a single B cell clone; produced by hybridoma; specific to one epitope, used in research
Monoclonal antibodies
