Part 5

Question 1

in the humoral response what is happening?

Answer 1

• B cells once activated are producing antibodies that go and bind to antigens that are extracellular ( haven’t yet infected cells.

Question 2

in the cell mediated response what is happening?

Answer 2

• Cytotoxic T cells once activated are in the position to recognize bad antigens and go out to kill infected cells

Question 3

what is culmination?

Answer 3

• The actual mounting of a response.

Question 4

describe the process of culmination in B cells?

Answer 4

• antibodies basically secreted versions of the B cell receptor, they contain a constant and variable regions.
• The variable region is what is binding to the antigen.
• These antibodies are being produced in large amounts
  (basic antibody notes.)
  ——————————————————————————
• ## antibodies work in a variety of ways, in one case they can trigger opsonization
• ## antibodies covering the surface of a pathogen can sometimes trigger neutralization of a phagocytic cell.
• ## because the antibody receptors have two arms one antibody can simultaneously bind to two antigens, and if the antigens are on different pathogens you cross link a bunch of these together (agglutination)- which keeps the pathogens bunched together and prevents them from spreading freely.
• some compliment proteins are activated in response to some antibody binding to a specific target. in some cases if the pathogen is covered in the antibody and the compliment protein is around and binds to it… it becomes activated. so then the complement protein kills the pathogen. (co-stimulation of complement proteins)

Question 5

what is opsonization

Answer 5

• just phagocytosis by a neutrophil, macrophage, etc. of something that has been covered in antibodies.
• you have a bacterium covered in antibodies and that goes to bind to receptors on the phagocytes surface, which helps to trigger phagocytosis.

Question 6

what is neutralization?

Answer 6

• a pathogen covered in antibodies prevents the cell from interacting with the desired phagocytic cell via a physical barrier..

Question 7

Describe the indirect ELISA test?

Answer 7

• lets say your showing symptoms of the flu and your doctor wants to test you for influenza A or B and he draws you blood.
• He then puts your blood into a multi-well dish.
• the well has already been coated with fragments of a known antigen, previously by the pharmaceutical company
• Then once your blood has been added and if your blood contains antibodies for those antigens, it’ll stick
• then the wash off anything that hasn’t stuck and add secondary antibodies.
• then the enzyme from the secondary antibodies will cause the well to turn yellow if it identifies your antibodies bound to the pre placed antigen
  ( Very mis-simplifiied.)

Question 8

Describe culmination via cytotoxic T cells

Answer 8

• cell mediated response. Cytotoxic T’s will be destroying antigens they recognize once activated.
• once a virus has hijacked a host cell’s machinery it is in a position to make new virions.
• remember that cells are randomly sampling proteins and once they chew them up via proteasomes and then displaying them via MHC class one on their surface.
• ## so it will in turn show fragments of viral proteins as well as its own on its cell surface.
• then if an activated cytotoxic T cell with the correct antigen receptor binds to one of the pathogen proteins , then the cytotoxic T cell will dock onto the cell and carry out a signaling pathway.
• this will cause the cytotoxic T cell to do two things:
  #1: secret proteins that will assemble into the membrane of the infected cell and cause it to make a pour.
  #2: Then the cytotoxic T will secrete cells that will trigger apoptosis
• then a phagocytic cell pulls up and munches on the remaining pieces.

Question 9

What happens to the culmination response to an antigen the more times it is presented?

Answer 9

• the response is faster and stronger. (immunological memory)

Question 10

What is the basis for immunological memory?

Answer 10

• when a T or B cell is activated, the majority of these cells try to carry out culmination (effector cells). But a subset of the cells refrain from immediately carrying out culmination (memory cells)
• MEMORY CELLS is the basis for immunological memory… they remain in active but carry the receptor to be able to bind to the antigen, so when it is seen again you already have a much greater basis of cells that trigger the production of more effector cells.

Question 11

What is the basis for vaccination?

Answer 11

• immunological memory:
• when your get a vaccine for a virus you are typically injected with fragment for that virus that has been killed by heat.
• once you have been injected by viral antigens you activate B cells and T cells, and a subset of those become memory cells, the other larger subset, effector cells, kills off the pathogen.
• the memory cells persist in the body for years so that if you are ever exposed to that virus/antigen again you now have more B and T cells with the needed receptor to get activated and rid of it.

Question 12

What are hypersensitivity disorders?

Answer 12

• overactive, or misdirected immune response.
  allergies and asthma- primarily a result of overactive components of the innate immune system.
• Autoimmune disorders: a result of the adaptive immune response against self-antigens (e.g. multiple sclerosis, lupus)

Question 13

What are immunodeficiency disorders?

Answer 13

• caused by an immune system that is non/weakly functioning.
• Primary immunodeficiencies: genetic basis to the immunodeficiency (SCID)
• Secondary immunodeficiencies: are acquired (AIDS)