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37 Cards in this Set

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What is an antigen?
Molecules that trigger specific immune response
Describe 3 main types of antigens
1. Exogenous - external to our body cells; most bacteria and toxins (Exp: Strept)
2. Endogenous - antigens from virus or extracellular bacteria that gets into a normal cell comes from inside and components get put on surface of cell as marking
3. Autoantigens - normally on the surface of normal body cells. "I'm suppose to be here tag; SELF."
What is an antibody?
a.k.a. immunoglobins
soluble proteins that bind antigens which are secreted by plasma cells
What are the main functions of antibodies?
1. Neutralization of toxins by binding to a critical portion of the toxin so it can't function against the body.
2. Opsonization - molecules that stimulate phagocytosis.
3. Killing by oxidiation - antibodies have catalytic properties that allow them to kill bacteria directly.
4. Agglutination (Aggregation) - each basic antibody has two-antigen-binding sites, each can attach to two antigenic determinates at once. When several immunoglobulin molecules binding with two microbial cells is agglutination
5. Activation of complement
6. Stimulate inflammation
List the 5 major classes of anitbodies and the properties of each antibody class
1. IgA (10-15%)
function: agglutination and neutralization
structure: Monomer (160,000); dimer (385,000)
location: Mucous membrane secretions, including milk
2. IgD (<1%)
function: unknown
structure: Monomer (184,000)
location: B cell surface
3. IgE (<1 %)
function: Triggers release of histamines from basophils and mast cells
structure: monomer (188,000)
location: serum, mast cell surfaces
4. IgG (80%)
function: complement activation, aggutination, opsonization, and neutralization; crosses placenta to protect fetus
structure: monomer (150,000)
location: serum, intercellular fluid
5. IgM (5-10%)
function: complement activation, agglutination, and neutralization
structure: penatmer (970,000)
location: serum
Whay is the lymphatic system?
Composed of lymphatic vessels, which conduct the flow of lymph (liquid), and lymphatic cells, tissues, and organs which constitute a survelliance system that screens the tissues of the body particularly the points of entry.
What organs and tissues are associated with the lymphatic system?
1. Lymph vessels - provide a 1-way system that transports lymph from local tissues to circulatory system.
2. Lymphoid cells - develop from stern cells in bone marrow, included B and T lymphocytes. (T-lymphocytes mature in the thymus)
3. Lymph nodes - contain leukocytes and are concentrated in specific regions. They recieve lymph from afferent lymphatic vessels and drain lymph into efferent lymphatic vessels
4. Spleen - similar in structure/function to lymph nodes, filters bacteria, viruses, toxins and other foreign matter from the blood
5. Tonsils and mucosa-associated lymphoid tissue (MALT) - physically trap foreign particles and microbes. MALT consists of appendix, lymphoid tissue of the respiratory tract and Peyer's patches
What are the 2 main types of lymphocytes? How do they differ?
1. B lymphocytes -
arise and mature in red bone marrow
2. T lymphocytes -
produced in the red bone marrow, but mature in the thymus.
What is the function of B-lymphocytes?
Secretion of antibodies
Are they involved in antibody or cell mediated response?
Antibody-mediated (humoral) response
What is BCR?
Are IgD antibodies on surface of B-cell.
Each B-cell has multiple copies of a single type of BCR.
Antigen binding site is identical to that of the secreted antibody for that particular cell
The randomly generated antibody variable region determines the BCR.
What is a plasma cell?
B-cells that are actively fighting against exogenous antigens
What is the function of T-lymphocytes?
Generates TCR (T cell receptor) for its cytoplasmic membrane. TCR's provide antigen-binding sites.
Are T-cells involved in the antibody-mediated response or cell-mediated response?
Cell-mediated immune response
What is a TCR?
An antigen-binding site on a T-cell
Name the types of T-cells
1. Cytotoxic T cells - (recognized by CD8 glycoprotein) activates enzymes within infected cell causing cell to self-destruct.
2. TH1 Helper T cell - (express CD26 and a cytokine receptor named CCr5) These cells assist cytotoxic T cells.
3. TH2 Helper T cell - (have cytokine receptors CCR3 and CCR4) assist B cells
Why do some antigens need processing?
Because smaller antigens have less accessible determinates so Helper T cells target therse antigens to make antigenic determinates more accessible
What is an APC and what is its function?
Antigen-presenting cell (APC) include macrophages and their functional relatives such as dendritic cells which are found in lymphoid organs and under the surface of the skin and are characterized by many long, thin cytoplasmic processes called dendrites. Their cytoplasmic membrane has about 100,000 MHC II molecules, which vary among themselves in the antigens they can bind
Distinguish between exogenous and endogenous antigen processing
Exogenous: (Extracellular bacteria)
- Phagocytized by macrophage
- Digested in phagolysosome
- Presented on MHC II

Endogenous: (Intracellular bacteria, viral and cancer proteins)
- Processed in endoplasmic reticulum
- Presented on MHC I
What glycoprotein distinguishes helper T-cells?
CD4 glycoprotein
How are TH2 cells activated and what is their function?
TH2 cells are activated
How are Th1 cells activated and what is their function?
TH1 cells are activated by and their function is to "help" regulate the b-cells and cytotoxic cells during an immune response
How are cytotoxic T cells activated?
They are activated by TH1 cells
What glycoprotein distiguishes cytotoxic t cells?
CD8 glycoprotein
Describe 2 pathways that cytotoxic T cells use to induce apoptosis
Secretes Perforin and granzyme and cells bind with autoantigens the cell will then undergo apotosis too.
Define apoptosis
Cell suicide
What are memory B cells?
- They DO NOT secrete antibodies.
- BCRs specific for antigen that triggered their production
- Long-lived cells that persist in the lymphoid tissue
- Available to initiate antibody production if the same antigen is encounteered again
What are memory T cells?
- TCRs specific for antigen that triggered their production
- Long-lived cells that persist in the lymphatic system
- Secondary immune response if exposed to same antigen again
What are cytokines?
Cytokines are soluble regulatory proteins that act as intercellular signals when released by certain body cells including kidney cells, skin cells and immune cells
Name the 5 main classes of cytokines
1. Interleukins (ILs)- signal among leukocytes
2. Interferons (IFNs)- antiviral proteins that may act as cytokines
3. Growth factors - stimulate stem cells to divide
4. Tumor necrosis factors (TNfs)- secreted by macrophages and T cells to kill tumor cells and regulate immune responses and inflammation
5. Chemokines - signal leukocytes to migrate
What are the MHC antigens and what is their funtion?
MHC antigens are membrane glycoproteins found on most cells. They hold and position antigens for presentation to the T-cell. Especially important in transplant patients so cells can identify self vs. foreign
In which cell types do you find MHC I?
all nucleated cells (RBCs no nucleus)
In which cell types doyou find MHC II?
Only in B-cells and antigen-presenting cells
Distinguish between primary and secondary immune response. What does primary reponse take longer?
Primary response is the first time a certain pathogen is introduced to the body. (The body slowly removes the pathogen while the body produces memory b-cells)
In secondary response, the memory B-cells immediately differentiate into plasma cells and proliferate, producing a response that is faster and results in greater sntibody production than occurs in primary response.
Distinguish between artifically-acquired and natural immunity.
Artifically-acquired is achieved by deliberately injecting someone with antigens in vaccines to provoke a response or the administration of preformed antibodies.
Natural immunity is when the body mounts a specific immune response against an infectious agent.
Define MHC
Major Histocompatibility Complex
Distinguish between passive and active immunity
Passive is when mothers pass babies in the fetus, or the administration of preformed antibodies. Whereas active is the body fighting off a pathogen on its own, or the administration of preformed antibodies.