BIOL 261: CH. 28 - IMMUNE DISORDERS AND ANTIMICROBIAL THERAPY

Allergen

an antigen that elicits an immediate hypersensitivity (allergic) reaction upon exposure

Antibiotic

a chemical substance produced by a microorganism that kills or inhibits the growth of another microorganism

Antimicrobial drug resistance

the acquired ability of a microorganism to resist the effects of an antimicrobial agent to which it was formerly susceptible

Autoantibody

an antibody that reacts to self-antigens

Autoimmunity

a harmful immune reaction directed against self-antigens

Beta lactam antibiotic

penicillin, cephalosporin, or a related antibiotic that contains the four-membered heterocyclic beta-lactam ring

Delayed type hypersensitivity

an inflammatory allergic response mediated by Th1 lymphocytes

Growth factor analog

a chemical agent that has a similar structure to and blocks the uptake or utilization of a growth factor

Hypersensitivity

an immune response leading to damage to host tissues

Immediate hypersensitivity

an allergic response mediated by vasoactive products released from IgE-sensitized mast cells

Immunotherapy

the treatment of a disease, especially cancer, using targeted therapeutic agents that either enhance or suppress the immune response

Nonnucleoside reverse transcriptase inhibitor (NNRTI)

a nonnucleoside compound that inhibits the action of retroviral reverse transcriptase by binding directly to the catalytic site

Nucleoside reverse transcriptase inhibitor (NRTI)

a nucleoside analog compound that inhibits the action of retroviral reverse transcriptase by competing with nucleosides

Quinolone

a synthetic antibacterial compound that inhibits DNA gyrase and prevents supercoiling of bacterial DNA

Selective toxicity

the ability of a compound to inhibit or kill a pathogen without adversely affecting the host

Sulfa drugs

synthetic growth factor analogs that inhibit folic acid biosynthesis in Bacteria

Superantigen

a pathogen product capable of eliciting an inappropriately strong inflammatory immune response by stimulating greater than normal numbers of T cells

Vaccination (immunization)

the inoculation of a host with inactive or weakened pathogens or pathogen products to stimulate protective active immunity

Vaccine

an inactivated or attenuated pathogen, or a harmless pathogen product, used to induce artificial active immunity

What is hypersensitivity?

An inappropriate immune response that results in host damage.

What are the two major types of hypersensitivity?

Antibody-mediated and cell-mediated.

What is another name for Type I hypersensitivity?

It is also called an immediate hypersensitivity reaction or simply "allergies."

What type of immune response mediates Type I hypersensitivity?

It is an antibody-mediated response involving IgE antibodies.

How quickly does a Type I hypersensitivity reaction occur?

It happens immediately after exposure to the allergen.

What is an allergen?

An allergen is any substance that triggers an immune response, acting as an antigen or immunogen.

What are some examples of Type I hypersensitivity reactions?

Examples include hay fever, bee stings, and severe allergic reactions.

What is commonly used to treat severe allergic reactions from bee stings?

An epinephrine auto-injector, such as an EpiPen, is used to counteract severe reactions.

What is Type II hypersensitivity?

Type II hypersensitivity is a cytotoxic reaction where the immune system attacks cells with bound antigens.

What is an example of a Type II hypersensitivity reaction?

A penicillin reaction occurs when penicillin acts as a hapten, binding to a serum protein and triggering an immune response.

What other type of immune reaction falls under Type III hypersensitivity?

An immune complex reaction, where antigen-antibody complexes form and lead to inflammation.

What is an example of an immune complex reaction?

Agglutination, where antigen-antibody complexes fall out of solution and clog capillary beds.

What can result from immune complex deposition?

Clogged capillary beds can lead to inflammation and conditions like arthritis.

What is Type IV hypersensitivity?

Type IV hypersensitivity is a cell-mediated response involving TH₁ cells that cause an inflammatory reaction.

What are examples of Type IV hypersensitivity reactions?

Poison ivy and nickel allergies, which are delayed-type hypersensitivity reactions.

Why are poison ivy and nickel allergies not contagious?

They are not infections; the reaction is caused by an oil (antigen) triggering an immune response.

What causes the blisters seen in poison ivy reactions?

Blisters result from the body's inflammatory response to the antigen.

What does a positive tuberculin test indicate?

A positive tuberculin test means you have tuberculosis, have had tuberculosis, were exposed to tuberculosis, or were vaccinated against tuberculosis.

What is histamine?

Histamine is a chemical released by the immune system during allergic reactions and plays a role in immune responses and inflammation.

What role does histamine play in allergic reactions?

Histamine acts as a vasodilator, causing blood vessels to expand and leading to symptoms like swelling, redness, and itching.

What causes autoimmune diseases?

Autoimmune diseases are caused by a loss of tolerance, where the immune system mistakenly attacks the body’s own cells.

How do autoimmune diseases work?

In autoimmune diseases, the body produces autoantibodies that target and attack its own cells.

What is an example of an autoimmune disease?

An example of an autoimmune disease is type I diabetes.

What happens in type I diabetes?

In type I diabetes, the antibodies target and attack the cells in the pancreas that produce insulin, causing them to be destroyed and resulting in no more insulin being produced.

What is staph aureus?

Staph aureus is a type of bacteria that can produce exotoxins, which are toxins made of proteins.

Why are the proteins produced by staph aureus important?

The proteins produced by staph aureus are great antigens, meaning they can trigger an immune response in the body.

What is scalded skin syndrome?

Scalded skin syndrome is a condition caused by staph aureus, where the bacteria’s exotoxins cause the skin to blister and peel, resembling a burn.

What is toxic shock syndrome?

Toxic shock syndrome is a severe condition caused by staph aureus exotoxins that lead to high fever, low blood pressure, and organ failure, often associated with tampon use or surgical wounds.

What is AIDS?

AIDS is an acquired immunodeficiency, meaning it is obtained from external sources, typically through exposure to HIV.

What role do TH cells play in AIDS?

TH cells, or T-helper cells, are the primary target of HIV.

• Without them, the immune system cannot function properly, leaving the body vulnerable to infections.

How does HIV affect TH cells?

HIV infects TH cells and buds out of them, taking a part of the cell membrane as it leaves, which helps the virus spread to other cells.

What is considered full-blown AIDS?

Full-blown AIDS occurs when the TH cell count drops below 200, whereas a normal count is around 600.

What happens when someone has full-blown AIDS?

When someone has full-blown AIDS, their immune system is severely weakened, making them highly susceptible to opportunistic infections that a healthy immune system could normally fight off.

What is vaccination (immunization)?

Vaccination is the deliberate exposure to an antigen, which triggers an adaptive immune response to protect an individual against future infections by a pathogen.

What is a vaccine?

A vaccine is the immunogen used to induce artificial active immunity by stimulating the immune system to recognize and fight a specific pathogen.

What is a toxoid vaccine?

A toxoid vaccine contains an inactivated toxin (protein) from a pathogen, like bacteria, that can cause disease.

What is the purpose of inactivating the toxin in a toxoid vaccine?

Inactivating the toxin makes it harmless while still allowing it to stimulate the immune system to produce antibodies against the toxin.

How does the body respond to a toxoid vaccine?

The body produces antibodies against the inactivated toxin, which remain in the blood as memory cells.

• These antibodies will neutralize the toxin if the body is exposed to it again in the future.

How does a live vaccine work?

A live vaccine introduces a weakened form of the pathogen that causes a subclinical infection, meaning the pathogen grows in the body without causing disease but still triggers an immune response.

What is meant by a subclinical infection in a live vaccine?

A subclinical infection means that the pathogen is able to replicate and interact with the immune system but does not cause noticeable illness because it is weakened or attenuated.

Why does a live vaccine trigger an immune response?

Even though the pathogen is weakened, it still stimulates the immune system to recognize it and produce a defense, including the creation of memory cells.

Why might live vaccines be a concern for immunocompromised individuals?

Immunocompromised individuals, whose immune systems are weakened, may not be able to control the live pathogen, which could potentially cause illness in these individuals.

What is a conjugated vaccine?

A conjugated vaccine links antigens together, often to help the immune system recognize certain pathogens more effectively.

What does it mean for a vaccine to be conjugated?

In a conjugated vaccine, a polysaccharide (sugar) from the pathogen's capsule is linked with a protein, which helps improve the immune response, especially for bacteria that have difficult-to-recognize capsules.

Why are bacteria with capsules targeted by conjugated vaccines?

Bacteria with capsules made of polysaccharides are harder for the immune system to recognize.

• Conjugating the capsule with a protein helps the immune system identify and attack these bacteria more effectively.

What is a subunit vaccine?

A subunit vaccine contains part of the pathogen, such as a protein, that triggers an immune response.

What part of the pathogen is used in a subunit vaccine?

Part of the pathogen, such as a specific protein (like the spike protein on a virus), is used to provoke the immune system without exposing the body to the full pathogen.

Why is a subunit vaccine effective without exposing the body to the full pathogen?

It allows the immune system to recognize and remember the pathogen’s key components without the risk of causing disease from the full pathogen.

What is a killed vaccine?

A killed vaccine contains pathogens that have been killed or inactivated, but still contain surface antigens that trigger the immune system.

How does a killed vaccine differ from a live or attenuated vaccine?

A killed vaccine uses dead pathogens, while a live or attenuated vaccine uses weakened or live pathogens.

• Killed vaccines do not cause the disease but still stimulate an immune response.

What role do the surface antigens of the dead pathogen play in immunity?

The surface antigens of the dead pathogen trigger the immune system to recognize and remember the pathogen, producing antibodies without causing illness.

What does "attenuated" mean in the context of vaccines?

"Attenuated" means that the pathogen in the vaccine is weakened, so it can still stimulate an immune response without causing disease.

What is a recombinant vaccine?

A recombinant vaccine is made by introducing genetic material into a host organism to produce a part of the pathogen, like a protein, that can stimulate an immune response.

Why would a vaccine be produced in cells from another organism, like E. coli?

E. coli or other cells can be used to produce large quantities of proteins quickly and efficiently, which can then be used as the immunogen in the vaccine.

How does a DNA vaccine work?

A DNA vaccine involves transforming host cells with DNA, causing them to produce proteins (antigens), which prompt the body to create antibodies against the antigen.

What happens to the DNA in a DNA vaccine after it is introduced into host cells?

The DNA is used by the host cells to produce proteins that resemble the pathogen’s antigens, which trigger an immune response.

How does the production of proteins (antigens) help trigger immunity in DNA vaccines?

The immune system recognizes the protein as foreign and produces antibodies and memory cells to fight the pathogen if exposed again.

How does an mRNA vaccine work?

An mRNA vaccine uses mRNA to instruct cells to produce a protein (antigen), which then triggers an immune response.

What happens when mRNA from a vaccine is introduced into cells?

The mRNA is translated into a protein, which is recognized by the immune system as foreign and prompts the production of antibodies.

How is the protein produced from the mRNA used to trigger an immune response?

The protein produced by the mRNA is identified by the immune system, which generates antibodies to fight the pathogen that the protein represents.

What happens to the mRNA after it has been used to produce the protein?

The mRNA is degraded by the body after it has been used to produce the protein.

What happens during the first exposure to a pathogen?

During the first exposure, the immune system produces IgM antibodies as the initial response to the pathogen.

What is the immune system’s initial response to a first infection?

The immune system begins producing IgM antibodies to fight the pathogen.

• This is part of the primary immune response.

What happens after a booster shot (second exposure)?

After a booster shot, the immune system produces IgG antibodies, which provide long-term immunity.

How do booster shots help the body produce IgG antibodies?

Booster shots prompt the immune system to respond more rapidly and effectively, leading to the production of IgG antibodies.

What is the significance of IgG in providing long-term immunity?

IgG antibodies are more specific and long-lasting, offering long-term protection against the pathogen.

What does it mean for the antibody titer to increase after a booster shot?

An increased antibody titer means that the concentration of antibodies in the blood is higher, which indicates stronger and more durable immunity.

What type of microorganism produces penicillin G and what is the specific genus?

Molds, specifically the genus Penicillium, produce penicillin G.

Which type of bacteria produces bacitracin?

Bacteria from the genus Bacillus produce bacitracin.

What type of microorganism is responsible for producing streptomycin?

Actinomycetes, specifically Streptomyces, produce streptomycin.

Where are penicillin G, bacitracin, and streptomycin-producing organisms commonly found?

All of these organisms are commonly found in soil.

What do molds, bacteria, and actinomycetes have in common regarding antibiotic production?

They all naturally produce antibiotics.

How does selective toxicity work?

It targets structures or processes found in pathogens but not in human cells.

What is an example of a drug that demonstrates selective toxicity?

Penicillin is an example because it blocks the crosslinking of peptidoglycan in bacterial cell walls.

Why does penicillin only affect bacteria and not human cells?

Human cells do not have cell walls, so penicillin does not affect them.

What is an antibiotic that kills both Gram-positive and Gram-negative bacteria called?

It is called a broad-spectrum antibiotic.

What is an antibiotic that kills only Gram-positive or only Gram-negative bacteria called?

It is called a narrow-spectrum antibiotic.

What does Cipro target in bacteria to inhibit their growth?

Cipro interferes with DNA gyrase, blocking the supercoiling of DNA and preventing replication.

What is competitive inhibition in the context of antibiotics?

It’s when a drug mimics a natural substrate, binding to an enzyme’s active site and preventing the actual substrate from binding.

How do sulfa drugs use competitive inhibition against bacteria?

Sulfa drugs resemble PABA, a precursor for folic acid synthesis, and when they bind instead of PABA, the bacteria can’t make folic acid.

Why do bacteria need to make their own folic acid?

Bacteria rely on folic acid for vital processes like DNA and protein synthesis, and they must synthesize it themselves.