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What does MHC stand for?

Major Histocompatibility Markers


What are the purpose of MHC?

They help the cells of your body distinguish them as self



A self marker
Contains a binding site for a protein fragment which the cell is producing
Red Blood Cells lack MHC I markers since they lack nuclei and cannot produce proteins; therefore red blood cells can be transfused


T/F: Red blood cells lack MHC I markers

T; since they lack nuclei and cannot produce proteins


Why do RBC lack MHC I markers?

They lack nuclei and cannot produce proteins; therefore, red blood cells can be transfused



Incorporate protein fragments from protein that were consumed by the cell
These are foreign proteins
Only presenter cells such as Phagocytic cells contain MHC II markers


Incorporate protein fragments from protein that were consumed by the cell
These are foreign proteins
Only presenter cells such as Phagocytic cells contain these:



Non-specific immune response

The defending cell are non-specific in what they attack


Specific Immune Response

Defending cell attacks one specific type of foreign invader



A specific non-self molecule that is recognized
They have antigenic determination sites
Ex: Chicken pox virus is the antigen, proteins on the viral coat that are recognized are the determination sites



They are made up of nucleic acid surrounded by a protein coat
They cannot make copies of themselves on their own; they need to invade other cells and get those cells to make more viruses
There are DNA and RNA viruses
Virus first has to attach to your cell and insert its DNA into the host cell's chromosome


If a virus is RNA based it is



T/F: As virus takes over a cell and makes new viral proteins it will insert fragments into the cell's MHC I marker, thus making the cell recognized as a foreign object



How does a retrovirus work?

A retrovirus inserts RNA, reverse transcribes and inserts into host genome thus forcing host cells to make copies of it


Phagocytic White Blood Cell

Monocytes become macrophages:
They are the "big eaters"
They are located in blood, lymph as well as tissue spaces
Some can hang out in specific organs giving them specific names
These cells can reshape and squeeze through a tiny opening: Diapedesis



The outward movement or passage of blood cells through pores in intact vessel walls


How do phagocytic cells work?



Endocytosis with phagocytic cells

Membrane of phagocytic cell surrounds and envelopes foreign entity
Membranes join and pinch off, forming a vacuole within
Digestive enzymes do their work on the vacuole: the enzymes are packaged in lysosomes, the lysosome will merge with the food vacuole, exposing the digestive enzymes to the vacuole; if lysosome explodes it can cause inflammation
As the entity is broken down to basic unites (amino acids, etc) it can be taken up to the membrane and released into the cell for use


Phagocytes move via

Pseudopods (fake legs)



Chemical communication attracting other phagocytes to area


Do the cells of our specific immune system get rid of foreign invaders?

No the cells of our specific immune system do NOT get rid of foreign invaders but make them easy for nonspecific cells to do their job


Specific Immune Cells

Lymphocytes; B-Cells, T-Cells


Lymphocytes are non-specific or specific?

Specific Immune Cells


Are B-Cells specific or non-specific?

Specific Immune Cells


Are T-Cells specific or non-specific?

Specific Immune Cells


Where do B-Cells start?

They mature in the bone marrow and stay there


Where do T-Cells start?

They mature in the bone marrow and go to the thymus gland


How do specific immune cells work?

These cells have immune receptors on their membrane that corresponds to an antigen on a pathogen
During development of B and T cells they start producing these immune receptors
The number of non-self molecules is potentially limitless
Binding of antigen to immune receptor on lymphocyte causes it to be activated; the cell starts to divide and make copies of itself: Clonal Formation


Describe the Immune Receptor Structure

Immune receptors have 2 copies of 2 different length proteins
The part that binds to an antigen is comprised of a portion of heavy chain and light chain:
Heavy chain: stem part is in membrane of B-cell
Light chain; variable region: varies from different immune receptors


Which are the most abundant classes of antibodies?

IgG and IgM


Where is IgA antibody associated?

In saliva and mother's milk


Where is IgE antibody associated?

Involved in inflammation response and allergy


Where is IgD antibody associated?

Rare floating freely in blood because the D is the constant region that inserts into B-cell membrane, therefore these are the immune receptors on its surface; it is used for the insertion of protein into the membrane of B-cell


Job of Plasma cells

Secrete immune receptors (antibodies) into the bloodstream;
Gamma globulins are another name for antibodies
Immunoglobulins are another name for antibodies
Plasma cells are antibody manufacturing plants


What is an antibody's primary job?

To bind to the markers on an antigen allowing for macrophages to easily eat the antigen


Which is the first antibody the body produces?

The body first produces IgM and then changes to IgG production


Why does the body change IgM production to IgG?

This change is mediated by chemicals that induce the plasma cells to change its constant region, thereby changing the class of antibody


What function do antibodies serve?

Complement Fixation


Explain neutralization as applies to antibody function

Antibodies prevent foreign particles from doing damage by coating them, preventing virus or bacteria from entering your cell; Antibodies do NOT kill antigens


T/F: Antibodies kill antigens



Explain Agglutination as applies to antibody function

Clumping of cells together;
Antibody bins to multiple virus/bacteria making them clump and preventing them from roaming freely in the blood


Explain Precipitation as applies to antibody function

Some foreign particles are too small such as foreign proteins which are soluble
Antigen stick to these particles to make them clump and insoluble. This makes the antigen precipitate out



The process that makes it easier for phagocytic cell to engulf the antigen coated with antibodies


How do antibodies help with opsinozation

There is a macrophage binding site at the ends of the constant region of the antibody which is why antibodies make phagocytosis occur more effectively


Explain Complement fixation as applies to antibody function

Complement proteins: group of plasma proteins produced by the liver
There is a complement binding site on the constant region of the antibody where complement proteins complex bind
When antibodies bind to a cell membrane they become aligned and clump together, complement proteins come and bind to 2 antibody causing them to release their complement proteins (know as an attack complex) which insert into the membrane to form a large pore disrputing the continuity of the cell membrane; the cell will lyse as its content are poured out, this only works for cellular pathogens such as bacteria (no virus or foreign porteins)
Phagocyte will come to clean up the garbage


T/F: Plasma cells produce 2,000 antibodies/second

True but they only last 3-4 days. We have clones of them so long as pathogen is around they will continue dividing. Once pathogen is gone, the B-cell will have nothing to stimulate it and it doesn't undergo clonal formation anymore


Explain how Active Immunity works

At the end of an infection, many B-cells remain in body as memory cells
These B-cells were never converted into plasma cells at the end of infection
Next time the same pathogen is encountered the memory cells were immediately stimulated and turned into plasma cells and antibodies were immediately dumped into the bloodstream and the pathogen is neutralized and killed before it even has a chance to make one sick
These B-cells have perfect or near perfect fit
This is known as active immunity


On first exposure to a pathogen or primary infection...

There is time needed for clonal formation
IgM secreted 1st, IgG secreted several days later


On secondary infection....

Memory cells are present
IgG is secreted in abundance immediately


How does Active Immunization work?

In Active Immunization we inject the viral protein coat but not the DNA/RNA into a person; the coat has the markers, but if DNA/RNA is not present then you cannot get sick


Why are some viruses hard to build active immunity to?

Some viruses mutate very quickly; such as the flu


How does Passive Immunization work?

The direct injection of antibodies into a person
This does not give you active immunity b/c once the antibodies are gone you can get sick again because memory cells were never formed


Why do we get passive immunity?

Some pathogens are so deadly that you cannot wait for an immune response to build up. Need antibodies ASAP


T/F: Mother gives antibodies to the child

T, mom gives baby antibodies across the placenta in the womb
Antibodies (IgA) are also transferred through the mother's milk


What are Antigen Presenting Cells (APC) & Explain their function?

Cells which have engulfed the antigen and digested it and put pieces of it on the MHC II Markers
You are now displaying markers of the antigen on your MHC II Markers
It might go to lymph node and then "present" this marker to a B cell
If the B cell matches up then it will bind and the B cells will be stimulated and undergo clonal formation; when the B cells are activated so are T cells
Both phagocytes and B cells can be presenter cells


T/F: Only presenting cells have MHC II markers?

T; all other body cells have MHC I markers "Self Markers"


T/F: When B cells are activated, T cells are also simultaneously activated



Purpose of T cells when virus infects

When a virus invades your cells, the cell will be forced to make viral proteins; the fragments of these proteins will be placed into the MHC I markers and therefore your body cell are now marked with foreign proteins
Some T cells may have immune receptors to match this foreign shape and undergo clonal formation upon contact


What are the 2 types of T-cells?

T-Cytotoxic Cells
T-Helper Cells


Describe T-Cytotoxic Cells

Kills body cells with foreign MHC I marker
Their immune receptors alone cannot bind to foreign protein fragment on MHC I marker; a second marker on the cytotoxic t cell called CD8 is required to work in conjunction with the immune receptor in order to bind properly
Kills body cell by causing the cell to lyse and fragment
These cells give off cytokines
Before secreting cytokines, the T cells must first undergo clonal formation, becoming immunocompetant by binding to infected cell and becoming stimulated; the offspring of clonal formation often have better fit to foreign proteins, causing greater stimulation and more secretion of cytokines
After chemicals are secreted and corrupted body cells are killed, memory cells will remain (Active Immunity)


T/F: T-cytotoxic cells bind directly to foreign protein fragments on MHC I marker

T-Cytotoxic cells immune receptors alone cannot bind to foreign protein fragment on MHC I marker
A second marker on the Cytotoxic T-Cell called CD8 is required to work in conjunction with the immune receptor in order to bind properly


How do T-Cytotoxic cells kill body cells

Cause cell to lyse and fragment
Perforin is the chemical that binds to cell membrane, forming holes and making it blow up
Causing cell to undergo apoptosis = cell suicide



Cell suicide


T-Cytotoxic cells give off what chemical?

Cytokines- chemicals given off by one cell that trigger response in neighboring cell (Paracrine System); this is a general term, there are many types of cytokines



Chemicals given off by one cell that trigger response in neighboring cell


Function of T-Helper Cells

Helps the system by secreting cytokines
Cytokines are responsible for triggering many of the stages in the immune response such as clonal formation and formation of plasma cells


What are the markers of T-Helper cells

Immune receptor - binds to foreign protein
CD4 - binds to MHC II


What is Interleukin 1?

Many cytokines are called Interleukins
Interleukin 1 is given off by presenter cell to the helper T cell;
This stimulates the helper cell to start clonal formation and is necessary for continuation of clonal formation (becoming immunocompetant)


Do B-Cells & Helper T Cells kill infected body cells?

No but they are very important to the immune response


What is Interleukin 2?

Given off by helper T-cell
Stimulates phagocytic cells to become more phagocytic and also stimulates immunocompetant T-cells (other helper cells or cytotoxic cells)


What is Interleukin 4?

Given off by helper t cells
Acts on plasma cells to start making IgE and IgG


What is IgE antibody associated with (may have been asked already)?

Moves through blood and tissue fluids and are incorporated into mast cells


Given off by helper T-cell
Stimulates phagocytic cells to become more phagocytic and also stimulates immunocompetant T-cells (other helper cells or cytotoxic cells)

Interleukin 2


Given off by helper t cells
Acts on plasma cells to start making IgE and IgG

Interleukin 4


What are Mast Cells?

Are derived from basophils in blood and they move to tissue spaces and reside there, becoming mast cells
May have a variety of IgE antibodies that it put into its membrane
They are not lymphocyte, they don't have immune receptors but they can acquire them in the form of IgE antibodies
When a mast cell encounters an antigen that binds to one of its acquired receptors it secretes:



Potent Vasodilator
Get a lot of blood to the are and more fluid leaks out of capillaries, forming tissue fluid. This causes inflammation as the area swells up with fluid



Prevents clotting


T/F: Any IgE antibodies the body makes can be incorporated into its membrane, not just one type

This allows mast cells to react to a wide variety of antigens
Mast cells will secrete chemical once it gets into contact with ntigen


The inflammation response

Vasodilation caused by Histamine which causes more leakage & inflammation in the area
Increase in capillary permeability; things like antibodies, clotting factors, complement proteins and antigens can now go through capillaries


Inflammation via Mast cell

Mast cells release heparin, prostaglandins, and histamine


T/F: Neutrophils have toll-like receptors (TLR) which bind to classes of markers on bacteria/fungi worms (non-specific to bacterial species)

This aids in phagocytosis



Are small molecules that can illicit an immune response if it binds to normal proteins


What causes a fever?

A fever is the resetting of the thermostat of the body
The body's thermostat is the hypothalamus
Some chemicals are given off by white blood cells that act as pyrogens that can reset the thermostat
At that point you will feel cold because your body temperature is below the "new" thermostat setting


B-Cells, Macrophages, and Dendritic cells are all

Antigen Presenting Cells; they are all phagocytic


In first exposure to antigen what are the major component of immune response



In second exposure what are the major component of the immune response?

B-Cells since immunity is built up from first exposure


What do dendritic cells present to?

T-helper cells (CD4 binds to MHC II)
Cytotoxic T-cells (CD8 binds to MHC I)


T/F: Do dendritic cells put fragments of antigen on both MHC I and MHC II markers

Cytotoxic T cells and Helper T cells then bind to their respective markers
The MHC I binding is temporary and done only during the presentation process


What is the main purpose of dendritic cells?

To present to other WBC; they are common in connective tissues of body
They are useful presenters in viral infections and tumors and cancers



A type of cytokine
They're not lymphokines, they're produced by the body cells that have been infected by a virus
Interferon will act on neighboring cells which inhibit viral uptake by neighboring cells


Red Blood Cells

Have no nucleus, ER, ribosomes or any protein manufacturing capabilities; therefore they cannot be infected by a virus
Have no MHC I markers since they cannot make it
They do have surface markers on them


What are the types of markers on a red blood cell?

If cell only has A markers its type A
If cell only has B markers its type B
If it has both its type AB
If it lacks all markers its type O


What are the genotypes of blood?

AA - Type A
AO - Type A
BB - Type B
BO - Type BO
AB - Type AB
OO - Type O
A & B are co-dominant alleles where O denotes the absence of either A or B


What antibodies do each red blood cell type have?

They make antibodies towards what they have never been exposed to
Type A has anti-B antibodies premade
Type B has anti-A antibodies premade
Type AB lacks antibodies so its called the universal recipient
Type O have both A & B antibodies so called the universal donor


What happens to a person with Rh - blood if they are given Rh + blood?

The Rh+ blood given is treated as an antigen and triggers an immune response which produces antibodies against the Rh+ marker
Creates active immunity
The transfused blood will be wiped out
If you are Rh+ you can receive either Rh+ or Rh- blood
If you are Rh- you can only receive Rh-


T/F: If you are Rh+ you can receive either Rh+ or Rh- blood?



T/F: If you are Rh- you can only receive Rh-



T/F: Antibodies can cross the placenta during gestation and immunize the developing fetus (passive immunity)



If the mother is Rh- and the fetus is Rh+ then...

Some Rh+ cells may enter the mother and she will develop an active immunity to the Rh marker (factor)
The baby is fine when its born but the mother now has anti-Rh antibodies in her body. These can pass through the placenta to affect the 2nd fetus in the future
If the second child is also Rh+ then it can cause erthroblastosis fetalis, the 2nd baby might die in development or have severe anemia at birth



Name of the antibody shot used to passively immunize the mother against Rh marker prior to birth