Adaptive immunity Flashcards
adaptive (acquired, specific) immune response
- acts against a specific intruder
- acquired when a pathogen is encountered for the first time
- has memory:
- responds more vigorously the second time a particular pathogen is encountered
adaptive is divided into two branches
- humoral (antibody mediated) immunity
- cellular (cell mediated) immunity
antibodies are also called (Ab)
immunoglobulins (Ig)
glycoproteins are composed of 4 subunits
- 2 identical heavy chains
- 2 identical light chains
each antibody has..
- 2 identical antigen binding sites (Fab)
- one Fc site- can interact with other components o the immune system
5 classes of antibodies
- IgG
- IgM
- IgA
- IgD
- IgE
Immunoglobulin G (IgG)
- monomer
- most abundant antibody in blood and tissues
- most important for combating a pathogen
IgM
- a pentamer
- first antibody made when a new antigen is encountered
- excellent at agglutination
- does not leave blood and enter tissues
IgA
- a dimer
- secreted into saliva, tears, mucous
- helps to protect mucosal surfaces
IgD
- monomer
- found on the surface of B cells
- plays a role in activating B cells to respond against an antigen
- diamond antigens instead of triangle
IgE
- monomer
- found on the surface of mast cells and basophils
- causes them to release granules of histamine
- trigers allergic response
- extra long light chains
five major functions of antibodies
- 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
Opsonization
- 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 found to a bacterial cell can activate complement
- A set of proteins in the blood that assist other components of the immune system
- classical pathways of complement activation
- results in the membrane attack complex (MAC)
- insert into bacterial membranes
- forms a pore
- cell leaks and dies
adaptive response properties
- acquired
- specific
- memory
- tolerance
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 ben encountered immune system cells multiply and produces long living memory cells
-if the pathogen is encountered again, the memory cells will mount a faster, stronger response
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
- the major result is the production of immunologic memory
secondary respond
the next time that pathogen is encountered memory cells are ready to respond
- response can be so quick that the pathogen is unable to cause disease
ie. immunity
immunogen
any foreign particle that can induce an adaptive immune response
-normally large molecules- proteins, polysaccharides, some lipids
antigen
any substance that can react with antibodies or receptors on adaptive immune system cells
antibody
protein made by the immune system that can bind to, and inactivate foreign antigens
epitiope
(or antigenic determinant)
- the actual part of the antigen that can bind to an antibody
- the more epitopes on an antigen, 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
hapten example
penicillin is small and non-immunogenic on tis own
- can bind to proteins in the blood forming a strong immunogen
- antibodies are formed against it-leading to an allergic response
cells of the adaptive immune system
- b lymphocytes (B cells)
- T lymphocytes (T cells)
B cells
- antibody producing cells
- involved in the humoral immune response
T cells
- T-cytotoxic cells (Tc cells)
- T-helper cells (Th cells)
Tc cells
- destroy abnormal body cells (ex. cells infected by viruses)
- involved in cel mediated response
Th cells
Help B and Tc cells prepare for an immune response
-humoral and cell mediated
