Unit 3 - Adaptive Immunity Flashcards
Which cell is the link between the adaptive and innate immune systems?
Dendritic cells
Identify what the innate and adaptive aspects of the dendritic cells are
Innate = phagocyte Adaptive = antigen-presenting cell
What is the name for the non-specific features that are recognized by the innate immune system?
PAMPs
- the same pattern COULD be on multiple bacteria species
What is the name if the specific molecule that may be used by the adaptive immune system to identify a specific pathogen?
An antigen
What is on the surface of lymphocytes that is able to bind to specific antigens?
Receptors
Which cells are lymphocytes that are part of the adaptive immune response (2)?
- B-cells
2. T-cells
True or False:
Toxins can be ligands that bind to receptors
True
What are immunoglobulins?
Receptors on B-cells that bind to antigens
What happens to a B-cell that binds to the antigen that it’s been looking for?
It become PARTIALLY activated!
- a T-helper cell would make it FULLY activated
What happens to the B-cell and it’s immunoglobulins (Ig’s) if it is fully activated by a helpter T-cell?
The receptors are secreted as antibodies
True or False:
Each individual B-cell or T-cell only recognizes one unique antigen
True
What section of the antigen does a b-cell or t-cell receptor recognize/bind to?
The epitope
What are the things that epitopes must have in order to be functional?
- Minimum 4-6 amino acids
- 3D shape
- Multiple epitopes
True or False
The amino acid sequence of an epitope is more than the 3D shape
False
- 3D shape is more important than the amino acid sequence
True or False
All antigens are immunogens
False
- Immunogens always produce an immune response
- Not all antigens mount an immune reponse
Define immunogenicity
The ability of a substance to elicit an immune response
What are 4 factors that contribute to the immunogenicity of an antigen or immunogen?
- Chemical composition
- Molecular size
- Foreignnes of the molecule
- Extrinsic factors (adjuvants)
Which molecule classes are more immunogenic, proteins, carbohydrates or lipids - why?
Proteins
- lipids are too fluid, they don’t have a rigid shape
- carbs have are weakly immunogenic
What do perfumes and colognes contain that cause an allergic reaction?
Aromatic compounds
- these can be recognized by the immune system and stimulate an allergic response
What size of molecule is too small to generate an immune response?
< 1000 Da
< 10,000 Da are poorly immunogenic
What is a Hapten?
A small antigen
- cannot initiate an immune response
What is the function of a carrier?
It is a large substance that binds to a Hapten
- now the Hapten is large enough to stimulate an immune reponse
What is the name of the structure, when a hapten binds with a carrier?
Hapten-Carrier Complex
True or False:
The likelihood of a hapten binding (“conjugating”) to a carrier is high
False
- the likelihood of a hapten binding is relatively low
What does it mean if a person is sensitized to a hapten?
It means that the hapten has been bound to a carrier
- it will elicit an immune response
What happens if a person has been exposed to a conjugated hapten (that elicited an immune response), and then the next time the person is only exposed to the hapten (no carrier)?
The immune system MAY respond to unconjugated hapten = allergy
- this happens with some metals
- when people develop allergies to metal
Is it possible that some sugars, amino acids and drugs (or drug metabolites) are haptens?
YES!
- for instance penicillin
Explain why some people have a drug allergy to penicillin.
Penicillin is too small on its own
- when drug degrades, it can react with (bind with) proteins
- this makes it large enough to elicit a response
- immune system will keep a memory of the penicillin allergy
In the case of a penicillin allergy, what is the hapten and what is the carrier?
Hapten = penicillin Carrier = protein
Why can someone get hemolytic anemia due to an antibody production against penicillin?
RBCs can have conjugated penicillin attached to the surface
- antibodies attach to the surface and mark it
- complements will lyse the cell b/c of antibody markers
True or False:
In order for a molecule to be immunogenic, it should be static, > 10,000 Da and have multiple epitopes
True
Which structure has greater immunogenicity (aromatics, linear, or bent)?
Aromatics = most Bent = middle Linear = least
What happens to lymphocytes that recognize self-antigens during maturation?
They are removed!
- we don’t want lymphocytes attacking ourselves
Give an example of molecular mimicry
Microbes that have evolved protein epitopes that resemble human proteins
True or False:
Your adaptive immune system will not react to tumor cells
True!
- tumor cells are your OWN cells
- adaptive immune system will NOT react to “self”
Why is a Group A Streptococcus infection so deadly?
Strep cells components mimic the shape of human proteins in heart, kidneys, joints, etc
- autoantibodies will react to BOTH strep AND human cell structures
= you make antibodies against yourself!
= Rheumatic fever
What does cross-reacting mean?
Antibodies that target similar epitopes on unrelated substances
Give an example of when cross-reacting occurred
1940s
- women were diagnosed with STD syphillis
- actually had lupus
Explain WHY lupus was diagnosed as syphillis
- Cardiolipin is found on surface of bacteria (such as syphilis)
- it is also on the surface of mitochondria
- For patients that have LUPUS, antibodies are made that CAN GO INSIDE THE CELL, and they find the cardiolipin on the mitochondria, not on the bacteria
= Auto-antigen!
True or False:
Botulism is an exotoxin, so we can make antitoxins against it
True!
How does serum sickness occur?
- Expose horse to botulism
- Collect serum from horse
- Expose patients to serum (with antibodies against toxin)
- Patients got sick! (Cytokine storm)
- Patients reacted to the foreignness of the horse serum components
What is an autograft?
Transplant from self-self
What is an isograft?
Transplant from genetically identical twin-twin
What is an allograft?
Transplant from the same species
What is a xenograft?
Transplant from a different species
How are auto-antigens able to generate an immune response?
Modification to normal proteins
- stimulation of autoimmune response can cause normal proteins to become recognized as antigens (auto-antibodies)
What are allo-antigens?
Antigens derived from other people
What are two example of allo-antigens?
- Blood transfusion (blood group antigens = A, B, and Rh)
2. Organ transplant (human leukocytes antigens (“tissue type”))
What is biobanking?
Hematopoietic stem cells are collected from umbilical cord blood, and stored if there is a risk of an inherited hematological disease