Immunology

Immunology
Body Defense Against Disease
Antigens
An antigen is any foreign substance that enters the body and stimulates the production of antibodies.
They have one or more sites called antigenic determinants that antibodies and/or lymphocytes can bind to.
Components of the Immune System\Types of Antibodies
Lymphocytes (white blood cells)
Three types
B cells
T cells
NK (natural killers) cells
Develop from lymphoid stem cells in the bone marrow
B cells
Migrate to the lymphoid regions of the intestine and liver
Produce antibodies that circulate in the lymph system and blood stream
Provide Humoral immunity
Only live one to two weeks
Quickly mass produce antibodies
T Cells
Migrate to the Thymus gland to differentiate into four types:
Helper T cells
Suppressor T cells
Cytotoxic T cells
Delayed-hypersensitivity T cells
NK (Natural Killer) cell
Destroy tumor cells and virally infected cells
Antibodies
Are glycoproteins produced by B cells
Y-shaped
Bind to the receptor site(s) of the specific antigen that stimulated their production
Placed in a class of proteins called immunoglobulins (Ig)
Found in lymph fluid, colostrum, tears, and saliva
Antibodies
Immunity Response
Lag Phase
After a person is exposed to an antigen, there is a delayed response in the production of antibodies called the lag phase.
The antigen is involved with macrophages, T cells, and B cells.
Some antigens only require B cells.
Eventually some of the B cells turn into larger plasma cells that can produce antibodies by protein synthesis.

The first step of the immune response is called the primary response.
When the number of antigens declines, the number of antibodies in the bloodstream also declines as the plasma cells die
Secondary Response
Other B cells become memory cell to protect against future infection
The production of the antibodies after re-exposure is called the secondary response
This is why titers are drawn to check the level of antibody concentration in the blood
Types of Immune Responses

Cell-mediated immune response (CMI)
Antibodies cannot enter cells, even those with intracellular pathogens
Mainly used against viral antigens
Uses Macrophages and T cells to control chronic infections
CMI controls but does not eliminate the cause of infection.
Example: Herpes
Types of Immune Responses
(Continued)
Humoral Immunity
Involves Helper T cells and B cells in the production of antibodies
T cells stimulate the production of antibodies from B cells
They do not produce antibodies themselves
Some B and T cells remain as memory cells to protect against future invasion of the same antigen
Types of Immunity
Genetic (inborn) Immunity
Is programmed into one’s genetic makeup
Does not involve antibodies
Varies between individuals, nationalities, racial groups, and species
Example: Ebola
Types of Immunity
(continued)
Acquired Immunity
Involves the use of antibodies
May be naturally acquired or actively acquired
May be active or passive
Types of Immunity
(continued)
Active immunity
The body produces its own antibodies in response to antigens
Naturally Acquired Active Immunity
Individual contracts disease, and then produces own antibodies and long term memory cells to that specific disease
Artificially Acquired Active Immunity
Individual is administered a vaccine, then the body produces antibodies to the antigen
Although this produces
long term immunity,
booster shots may be
needed to maintain
antibody levels.
Passive Immunity
Antibodies from an outside source are introduced into the body; body does not produce its own antibodies
Naturally Acquired Passive Immunity
Mother’s antibodies pass through placenta to fetus or through breast milk to infant
Artificially Acquired Passive Immunity
Antibodies produced elsewhere are injected in the form of immune serums
Artificially Acquired Passive Immunity
(continued)
Immune serums may be prepared in animals, other humans, or in the lab.
They only provide short-term immunity with no memory against future invasions.
Example: Immune globulin (gamma globulin) contains special antibodies and is commonly given to boost immunity when exposed to HepA

Allergic Response
Hypersensitivity Reactions
Hypersensitivity Reactions
Represent an immune response that is abnormal and can be mild to life threatening.
Instead of providing protection, the antibodies damage cells of the body.
Can be dangerous and life threatening
Symptoms can be from localized itching to anaphylactic shock
Hypersensitivity Reactions
(continued)
Is brought on by allergens which cause altered reactions in the body tissue of sensitized individuals but which produce no effect in non-allergic individuals.
Does not occur on first contact because antibodies have not been produced yet
It may occur on the second contact or take several contacts to produce enough antibodies to trigger a response.

Hypersensitivity Reactions
(continued)
Common allergens include:
Inhalants such as dust, pollen, and perfume
Foods such as wheat, eggs, milk, chocolate, and strawberries
Drugs such as aspirin and various antibiotics and serums
Other contactants such as animals, plants, hair, and fur
Anaphylactic Shock
A severe allergic reaction to a drug such as penicillin or a foreign protein such as insect venom
Body produces histamine or a histamine-like substance causing vasodilation, hypotension, and bronchiolar constriction.
Anaphylactic Shock
(continued)
Early reactions occur suddenly and include
Itching
Ringing in ears
Metallic taste in mouth
Difficulty breathing (larygospasm/brochospasm)
Elevated blood pressure (hypertension)
Increased heart rate
restlessness
Anaphylactic Shock
(continued)
Late symptoms
Rapid decrease in BP (hypotension)
Tachycardia
Nausea and vomiting
Confusion and inability to mentally focus
Respiratory failure
Death usually results from bronchiospasm
Individuals with prior anaphylaxis should always wear medical alert tags.

Anaphylactic Shock
(continued)
Treatment
100% O2
Epinephrine: causes bronchodilation, reduces laryngeal spasm, elevates blood pressure
Steroids: slows chain reaction taking place
IV fluids to maintain fluid volume
Levophed, a vasopressor agent used to increase blood pressure.
Hemolytic Transfusion Reaction
From blood transfusions that are not properly matched to the patient’s blood type
Symptoms of the awake patient include:
Lack of energy
Shortness of breath
Rapid pulse
Hemolytic Transfusion Reaction
(continued)
Surgical patients receiving general anesthesia do not display these signs.
The only noticeable signs may be diffuse loss of blood at the surgical site and decrease in O2 saturation (SaO2) due to the inability of the erythrocytes to carry oxygen.
In some cases pts must undergo dialysis in order to remove the mismatched blood.
Autoimmune Disease
Caused by the person’s immune system not recognizing certain tissues as a normal part of the body.
The body actually attempts to destroy the tissue because it is perceived as foreign.
Example:
Rheumatoid arthritis
Rejection Syndrome
May occur following transplantation of an organ or tissue.
Every organism has a natural tendency to reject foreign substances, especially tissues from another person or animal.
Tissue and organs are cross-matched much in the same way as blood.
Drugs that suppress antibody formation are used to decrease tissue rejection.