Microbiology Chp.16

Front 1

What is an antigen?

Back 1

Molecules that trigger specific immune response

Front 2

Describe 3 main types of antigens

Back 2

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."

Front 3

What is an antibody?

Back 3

a.k.a. immunoglobins
soluble proteins that bind antigens which are secreted by plasma cells

Front 4

What are the main functions of antibodies?

Back 4

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

Front 5

List the 5 major classes of anitbodies and the properties of each antibody class

Back 5

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

Front 6

Whay is the lymphatic system?

Back 6

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.

Front 7

What organs and tissues are associated with the lymphatic system?

Back 7

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

Front 8

What are the 2 main types of lymphocytes? How do they differ?

Back 8

1. B lymphocytes -
arise and mature in red bone marrow
2. T lymphocytes -
produced in the red bone marrow, but mature in the thymus.

Front 9

What is the function of B-lymphocytes?

Back 9

Secretion of antibodies

Front 10

Are they involved in antibody or cell mediated response?

Back 10

Antibody-mediated (humoral) response

Front 11

What is BCR?

Back 11

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.

Front 12

What is a plasma cell?

Back 12

B-cells that are actively fighting against exogenous antigens

Front 13

What is the function of T-lymphocytes?

Back 13

Generates TCR (T cell receptor) for its cytoplasmic membrane. TCR's provide antigen-binding sites.

Front 14

Are T-cells involved in the antibody-mediated response or cell-mediated response?

Back 14

Cell-mediated immune response

Front 15

What is a TCR?

Back 15

An antigen-binding site on a T-cell

Front 16

Name the types of T-cells

Back 16

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

Front 17

Why do some antigens need processing?

Back 17

Because smaller antigens have less accessible determinates so Helper T cells target therse antigens to make antigenic determinates more accessible

Front 18

What is an APC and what is its function?

Back 18

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

Front 19

Distinguish between exogenous and endogenous antigen processing

Back 19

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

Front 20

What glycoprotein distinguishes helper T-cells?

Back 20

CD4 glycoprotein

Front 21

How are TH2 cells activated and what is their function?

Back 21

TH2 cells are activated

Front 22

How are Th1 cells activated and what is their function?

Back 22

TH1 cells are activated by and their function is to "help" regulate the b-cells and cytotoxic cells during an immune response

Front 23

How are cytotoxic T cells activated?

Back 23

They are activated by TH1 cells

Front 24

What glycoprotein distiguishes cytotoxic t cells?

Back 24

CD8 glycoprotein

Front 25

Describe 2 pathways that cytotoxic T cells use to induce apoptosis

Back 25

Secretes Perforin and granzyme and cells bind with autoantigens the cell will then undergo apotosis too.

Front 26

Define apoptosis

Back 26

Cell suicide

Front 27

What are memory B cells?

Back 27

- 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

Front 28

What are memory T cells?

Back 28

- 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

Front 29

What are cytokines?

Back 29

Cytokines are soluble regulatory proteins that act as intercellular signals when released by certain body cells including kidney cells, skin cells and immune cells

Front 30

Name the 5 main classes of cytokines

Back 30

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

Front 31

What are the MHC antigens and what is their funtion?

Back 31

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

Front 32

In which cell types do you find MHC I?

Back 32

all nucleated cells (RBCs no nucleus)

Front 33

In which cell types doyou find MHC II?

Back 33

Only in B-cells and antigen-presenting cells

Front 34

Distinguish between primary and secondary immune response. What does primary reponse take longer?

Back 34

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.

Front 35

Distinguish between artifically-acquired and natural immunity.

Back 35

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.

Front 36

Define MHC

Back 36

Major Histocompatibility Complex

Front 37

Distinguish between passive and active immunity

Back 37

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.