Part 5: Overview of Adaptive Immunity Flashcards
Adaptive immune response
Acts against a specific intruder
Adaptive immune response branches
Humoral (antibody mediated) immunity
Cellular (cell mediated) immunity
Antibodies (Ab) are also called
Immunoglobulins (Ig)
Glycoproteins are composed of
2 identical heavy chains
2 identical light chains
Fab
2 identical antigen binding sites on the antibody
Fc site
Interacts with other components of the immune system
How many classes of antibodies are there?
5
Immunoglobulin G (IgG)
Monomer
Most abundant antibody in blood and tissues
Most important for combating a pathogen
Immunoglobulin M (IgM)
Pentamer
First antibody made when a new antigen is encountered
Excellent at agglutination
Does not leave blood and enter tissues
Immunoglobulin A (IgA)
Dimer
Secreted into saliva, tears, mucous
Helps to protect mucosal surfaces
Immunoglobulin D (IgD)
Monomer
Found on the surface of B cells
Plays a role in activating B cells to respond against an antigen
Immunoglobulin E (IgE)
Monomer
Found on the surface of mast cells and basophils
Causes them to release granules of histamine
Triggers allergic response
Antibodies have five major functions
Neutralization Opsonization Agglutination Antibody mediated cytotoxicity Complement activation
Neutralization
Ab stick to antigens on a foreign particle and block attachment sites - stops bacteria, viruses, and toxins from entering host cells
Opsonzation
Ab stick to a pathogen’s surface and flag down phagocytes
Phagocyte interacts with the Fc region and engulfs the pathogen
Greatly increases rate of phagocytosis
Agglutination
Ab can stick to two identical antigens
Bridges particles together in clumps
Can be phagocytized more easily
Antibody mediated cytotoxicity
Ab binds to antigen on the surface of a parasite
Fc can interact with eosinophils
Eosinophils release enzymes and reactive oxygen intermediates to attack the parasite
Complement activation
Ab bound to a bacteria can activate complement
Results in the membrane attack complex (MAc)
Insert into bacterial membranes
Forms a pore
Cell leaks and dies
Complement
A set of proteins in the blood that assist other components of the immune system
“Classical pathway” of complement activation
Acquired
A pathogen must be encountered before the adaptive immune response is mounted
Specific
Can mount a directed attack against a specific pathogen - immunity to one pathogen does not confer immunity to another
Memory
Once a specific pathogen has been encountered immune system cells multiply and produce long living memory
Tolerance
Inability to mount an adaptive immune response against self-antigens
Immune system cells that recognize self-antigens are destroyed during development
Primary response
The first time a new pathogen is encountered, the adaptive immune response is weak
