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48 Cards in this Set

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  • Back
Name 3 protective mechanisms that the INNATE system uses.
Barriers
Humoral Factors
Phagocytic Cells
Why can't pathogens survive on the skin?
1. Surface is dead and lacking nutrients
2. Acids in sweat and sebum
3. Commensal bacteria out-compete pathogens for nutrients
What are vulnerable areas (eyes, nasal passages) protected by with the INNATE system?
The bacteriocidal agent LYSOZYME, which digests bacterial walls
Name two phagocytic cells.
Neutrophils and Monocytes
What is a Pattern Recognition Receptor (PRR)?
On phagocytic cells, sense "dangerous" molecules and trigger phagocytosis.

Note: The Toll-like receptors are a major family
Opsonization
Promotion of phagocytosis
An immature macrophage is called what?
Monocyte
When does adaptive immunity come into play?
When the innate mechanisms have FAILED (aw, sad..)
How do the adaptive and innate systems work together?
Adaptive immunity improves and optimizes the efficiency of innate mechanisms, like complement, phagocytosis, etc.
Antigen
Foreign substances that stimulate an immune response
Dendritic cells are responsible for what?
Initial recognition of antigen via innate receptors
Where do T cells and B cells develop?
B cells - Bone Marrow
T cells - Thymus
What do B cells develop into?
Plasma cells, which secrete the antibodys
What are the two types of T cells?
CD4 - T Helper Cells
CD8 - Cytotoxic Killer Cells
Do Natural Killer cells express antibody or t-cell receptors?
Nope! They display surface receptors for antibodies and non-specific receptors. They are a part of the innate system and kill non-specifically.
How many receptors can a B or T cell express?
Thousands, but only of one specificity
Which MHC classes go with which T cell type?
CD4 Helper - MHC 2
CD8 Killer - MHC 1
What does the MHC do?
Presents antigen to the T cell receptor
What is the main type of antibody?
IgG, but IgM are the first to appear
Class switch is controlled by what?
T cells determine B cell differentiation
Where do B cells mature into plasma cells?
Bone marrow, splenic red pulp and lymph node medulla
What is the bodys first response to an antigen called?
Priming, and it includes a latent period of 7-10 days before antibody is detected
What is the complement system made up of?
More than 20 soluble complex proenzymes that are part of a cascade group
What are the two complement pathway types?
Alternative and Classical
Where is C3 made?
Made in the liver, but split in the blood
What is the main feature of the alternative pathway?
The absence of antibody. It instead is activated by bacteria, yeats and fungi
Which Factors in the plasma work to inactivate C3b?
Factors H and I
What are the main effects of the Alternative Pathway? (2)
1. To coat bacteria with iC3b to become major targets for phagocytes
2. To induce an acute inflammatory response via C3a and C5a
What are two triggers of the Classical Pathway of complement?
The binding of antibody to antigen or binding of soluble lectins (collectins) to pathogens
What complex does the classical pathway eventually produce, which can digest C3?
C4b2b enzyme
What is special about the "a" fragments of complement?
They are chemotactic for neutrophils and inducers of acute inflammation. Also called anaphylotoxins
What is MAC?
Membrane Attack Complex. This is the lytic pathway of complement function and is initiated via enzymes C3bBb3b or C4b2b3b.

Results in pore formation and cell lysis by osmotic shock.
What inhibits complement?
Factors H and I and Delay Accelerating Factor (DAF - only in classical)
What cells are MHC1 expressed on?
All except neurons and red blood cells
What is the function of MHC1 molecules?
To bind antigenic peptides derived from WITHIN the cell (i.e. virus!)
Which cells express MHC2?
Macrophages, dendritic cells and B cells
Does MHC1 or 2 interact with larger peptides?
MHC 2! Has a larger groove so interacts with peptides around 20 amino acids long, vs. the 8-10 that MHC1 can
What is the function of MHC2?
Interacts with CD4 T cells and presents antigenic peptides from an EXTRACELLULAR source (i.e. bacteria)
What is the function of CD4 T cells?
To regulate all aspects of both immune and innate response. Also secrete cytokines that influence many cell aspects.
Which are the most prominent lymphocytes in the blood?
CD4 - 50%

CD8 only 20%
What is the function of CD8 T cells?
To kill virus-infected cells
How many signals are required for a T cell to be activated?
2 - interaction of TcR with antigen and also interaction of T molecule CD28 with ligand on antigen presenting cell, CD80. This second signal only occurs after recognition of DANGER.
What happens if a T cell receives signal 1, but not 2?
It does into apoptosis as a control
If both signals (antigen and 'danger') are received by a T cell, what happens?
Cell is activated into clonal expansion and produces cytokines
What determines if a CD4 cell diffentiates into a TH1 or TH2?
TH1 if macrophages are the APC and TH2 if B cells are the APC
What is the role of IL-4?
Stimulates B cell growth and heavy chain switch
What are the roles of IL-5 and IL-6?
Activate B cells and stimulate proliferation
What is the differentiation of TH0 caused by?
Cytokines secreted by APCs - macrophages produce IL-12 and B cells produce IL-10