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60 Cards in this Set

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What is the function of the immune system?
Host defense against infection
What is the immune system designed to do?
Neutralize and eliminate pathogens
What is the definition of a pathogen?
A microorganism capable of causing disease
So what does the immune system target?
The molecules that make up microorganisms.
What is an Antigen?
Any molecule that CAN be recognized by the immune system
What is an Epitope?
The part of an antigen that makes DIRECT CONTACT with cells or proteins of the immune system
How is an Immunogen different from an Antigen?
It can not only be recognized, but also elicit an immune response.
What are the 2 main divisions of the immune system?
-Innate
-Adaptive
What are the main innate immune system cells?
PHAGOCYTIC CELLS
-Macrophages
-PMNS
How do phagocytic cells kill immunogens?
By eating them and degrading them
What are the main Adaptive immune system cells?
Lymphocytes - B and T
How do B lymphocytes function?
By secreting Antibody
What is the function of Antibody?
To bind pathogens and enhance phagocytosis
What is the type of adaptive immunity achieved by B cells called?
Humoral immunity
What are the 2 main types of T lymphocytes?
-T helpers
-T cytotoxics
What are T helper cells split into?
Th type I
Th type II
What do Thelper Type I cells do?
Secrete cytokines that help macrophages phagocytize better
What do Thelper Type II cells do?
Secrete cytokines that help B cells make more antibody
What do cytotoxic T cells do?
Secrete cytokines that directly kill pathogens
What do we call the type of immunity achieved by Tc cells?
Cell mediated
What are the 4 ways in which cells of the adaptive immune system differ from innate?
1. Diversity
2. Specificity
3. Self-tolerance
4. Memory
What gives diversity?
The fact that T and B cells are made of subpopulations of clones, each having a unique antigen receptor
What gives specificity?
The fact that each unique antigen receptor recognizes a specific antigen.
What allows self-tolerance?
The elimination of self-recognizing cells during B and T lymphocyte maturation and development.
What is the result of self-tolerance breakdown?
Autoimmunity
What does Memory refer to?
The increased kinetics and magnitude of a response to a particular antigen with repeated exposure.
What is Memory the immunologic basis of?
Immunization
What is the BCR?
Bcell receptor - the surface associated version of immunoglobulin, that may become secreted.
What is the BCR comprised of?
-2 heavy chains
-2 light chains
What links the heavy chains together? What links the light chains to the heavy chains?
Disulfide bridges
What is each heavy and light chain composed of?
Several domains each made up of 100 amino acids that are folded into a 3D conformation.
What are the domains that make up heavy and light chains called?
Immunoglobulin domains
Are Ig domains only found in antibodies and BCRs?
No it was just first discovered there.
What is the Variable Domain of each immunoglobulin domain?
The N-terminal part of it
How many Variable domains are on each BCR?
Four
-2 Vh - heavy chain N termini
-2 Vl - light chain N termini
What do these Variable regions vary between?
Clonal subpopulations of Bcells
What does the region made up by the Vh and Vl domains compose?
The unique antigen binding site that confers antigen specificity to a given clonal population.
What does this antigen binding site recognize?
An antigenic EPITOPE
What is an epitope?
A small number of amino acids in an intact protein that are close together in 3D space.
What do we call it when these amino acids are adjacent to each other in a polypeptide chain?
A linear epitope
What do we call it when these amino acids are originally distant from each other, but brought close by folding?
A Conformational epitope
How many antigen binding sites are on each BCR? Why?
2 - because the 2 H chains and 2 L chains make the BCR bivalent
What are the C-termini of the heavy chains called?
Constant domains
How many C domains are on light chains? Heavy chains?
Light - only 1 constant domain
Heavy - several constant domains
What does the type of C domain that a light or heavy chain have determine?
The subclass that the chain is in.
How many light chain subclasses are there? What are they?
2 - kappa and lambda
How many heavy chain subclasses are there in secreted BCRs (immunoglobs)? What are they?
5
-Gamma
-Alpha
-Mu
-Epsilon
-Delta
How are the heavy chain subclasses different? (4 ways)
1. In # of C domains they have
2. #/position of glycosylation sites
3. #/position of disulfide bonds
4. Functions
How is the TCR mainly different from the BCR?
It is only expressed on the Tcell surface and is never secreted.
What is each TCR composed of?
-One Alpha subunit
-One Beta subunit
-Linked by one disulfide bond
What is each alpha or beta subunit of a TCR made of?
2 immunoglobulin domains
What is the variable domain of the TCR?
The n terminus of each alpha or beta subunit.
What is the constant domain of the TCR?
The C-terminus
So what does the disulfide-bonded alpha and beta pair folded together confer?
The antigen specificity for that TCR clone.
What is the antigenic epitope that gets recognized by the TCR?
A Peptide/MHC complex
What is the peptide from?
Degraded antigen that has been processed by an APC.
Where is the MHC complex molecule encoded?
In the major histocompatability complex.
What cells express MHC 1? What cells recognize it?
All nucleated cells express MHC I and its recognized by Tc cells
What cells express MHC II?
Only APCs express MHC II and it's recognized by Thelper cells
What are APCs?
-Dendritic cells
-Macrophages
-Bcells