Introduction to Immunology Flashcards
Why is it important to wash our hands (in regular soap, i.e. non-antimicrobial)?
- Washing hands reduces risk of transmitting pathogens by person to person spread.
- Antimicrobials destroy our commensal organisms (that do not harm us and can help keep out pathogens as they compete for resources).
What are commensal microorganisms?
Those microorganisms that inhabit specific areas of the human body that do NOT cause disease or infection. They help prevent infections by competing with pathogens for space and food.
What are opportunistic pathogens?
Pathogens that normally do not cause disease in a healthy individual but if the immune system is compromised then the pathogen is able to cause disease.
What two things can help ensure a healthy immune system?
Diet and exercise greatly reduces the risk of any type for disease state that can inflict the human body.
What are the four classes of pathogens? Is there another potential class?
Viruses Bacteria Fungus Parasite Other (potential): Prions
What is the smallest known pathogen? How small can it be?
Viruses
Can be ~20nm in diameter.
Describe the basic structure of a virus (as per notes).
Simple structure.
Contain a nucleic acid genome (DNA or RNA) that is enclosed by a protein coat (capsid) and sometimes a membranous envelope.
What is a bacteriophage?
Could they be on our body/
- A virus that infects bacterium.
- Some research that suggests bacteriophage is within our mucus in mucosal linings that provide non-specific immunity. Infect and destroy bacterium that comes in contact with mucus.
How do viruses replicate?
- Viruses can only replicate within other cells and need a host (bacteria, plants, animals, humans, etc.).
- Recognizes a host by molecules on its surface, invades past the membrane and inserts its genome into the host cells nucleic acid genome, and the host cell will produce more viruses.
- They will continue until the host cell undergoes lysis.
What is the most commonly encountered pathogen?
Bacteria
Describe bacteria.
- Unicellular microorganism.
- Avg. size of 2 um length.
- Lacks organized nucleus
- Possess capability to grow and reproduce independently.
- Typically surrounded by a rigid cell wall.
- Can be found in many different shapes (which aids identification).
What shapes can bacteria be found in?
Cocci (round), rods, bacilli, spirillum, and curved.
T/F. bacteria can inhabit a wide variety of environments.
True
T/F. Maintaining healthy flora is important in maintaining good health.
True
What are the two categories of fungi?
Yeast
Molds
Describe characteristics of yeast (fungi)?
- Unicellular oval structures.
- Reproduce by budding.
- Non-photosynthetic plants.
Describe characteristics of molds (fungi)?
- Non-photosynthetic plants.
- Multicellular
- Forms clumps of blue-green or black (like on cheese/bread).
What type of pathogen is Streptococcus pneumonia?
Bacteria
What are parasites?
- Large variety of unicellular protozoa and multicellular worms found in water and soil.
- Causes disease by using all of host’s nutrients.
- Classified based on their life cycle/relationship with host.
What are prions?
- Infectious substances, but not living.
- “Prion Hypothesis” - misfolded proteins. (Debated theory)
- Mechanism by which they cause disease is not well understood.
Name an example of a disease state caused by a prion?
Creutzfeldt-Jakob Disease (CJD), a degenerative brain disease.
- Incurable and fatal.
- Often undetected until an autopsy is performed.
- Brain tissue in someone w/ CJD has holes, like sponge.
What causes Typhoid fever?
Salmonella typhi, bacteria
What causes Mononucleosis?
Epstein-Barr virus
What causes Thrush?
Candida Albicans,
Bacteria
What causes Tuberculosis?
Mycobacterium tuberculosis
Bacteria
What causes Malaria?
Plasmodium falciparum
Parasite
What are superantigens? Name one example.
Superantigens stimulate a much larger population of cells.
Example: Staphylococcal aureus - releases bacterial toxin which produces a massive immune response.
Symptoms: High fever, low blood pressure, coma, and … death.
What can antigens be made of?
Any macromolecule in existence can elicit an immune response.
Proteins, carbohydrates, lipids, and/or nucleic acids.
What is a hapten?
Non-immune stimulating compounds of small molecular weight that can be coupled with an antigen to create a new antigen. This changes the immune response stimulated.
What is the part of the antigen called that is actually recognized by the immune system?
Epitope
Also called ‘antigenic determinant’.
What are the characteristics of antigens?
- Foreignness - More foreign (degree of difference to host) –> more response
- Molecular Size - The larger the molecule the more antigenic (larger response)
- Chemical Nature - Generally more complex the more antigenic;
- Method of Introduction - varies whether injected, ingested or inhaled.
- Genetic Susceptibility - genes affect how well an individual will respond to an antigen.
What units are molecules measured in?
Da, dalton for size
Atomic mass unit for weight, ~ 1 nucleon = 1g/mol
Compare some molecular size of antigens reviewed in notes and the immune response they cause?
- Insulin <10,000 Da Poor response.
- Antibody of 150,000 Da, Good response.
- E.coli of 2,500,000,000 Da Great Response.
Get the idea?
Are there exceptions to the molecular size rule related to antigenicity? Example?
Yes there are some exceptions to the rule.
Penicillin has a molecular mass of 335 Da but is very immunogenic for some individuals.
Heparin (anticoagulant is 12,000-15000 Da is not immunogenic (fortunately).
List the molecules which are antigenic from the greatest to the least.
From High to low immune response:
Proteins (Great),
Carbohydrates (Good),
Nucleic Acids (DNA/RNA) (Poor), Lipids (very poor)
What gene helps people who posses it to have good immune responses?
IR gene - good immune responders compared to those who lack it.
What methods of introduction gives the greatest antigenicity?
Injected subcutaneously - more potent immune response than with ingested or inhaled.
What happens to our immune response if a vaccine dose is too large or too small?
If too large or small - immune response will be avoided.
Needs to be optimal concentration/amount!
Is it possible to exhaust your immune system?
Yes, it is possible to manipulate the immune system and create a state of exhaustion in an individual. By repeated and vigorous stimulation by an antigen - will cause eventual ceasing of the immune response. E.g. treating an allergy.
