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
What is the major result of primary response?
Immunologic memory
Secondary response
The next time that pathogen is encountered memory cells are ready to response
Response can be so quick that the pathogen is unable to cause disease - immunity
Immunogen
Any foreign particle that can induce an adaptive immune response
Normally large molecules - protein, polysaccharides, some lipids
Antigen
Any substance that can react with antibodies or receptors on adaptive immune system cells
Antibody
Proteins made by the immune system that can bind to, and inactive foreign antigens
Epitope
The actual part of the antigen that can bind to antibody
More epitopes on an antigen mean
The more immunogenic it will be and the more diverse population of antibodies can be generated against it
Hapten
Low molecular weight compound too small to be immunogenic on its own, but can be highly antigenic
Example of hapten
Penicillin
Penicillin is small and non-immunogenic on its own
Can bind to proteins in the blood forming a strong immunogen
Antibodies are formed against it - leading to an allergic response
