Antibodies - structure and function

Question 1

Adaptive immunity is made up of 2 connected systems. What are these 2 systems?

Answer 1

humoral immunity and cell-mediated immunity

Question 2

this type of immunity includes high specificity, immunological memory, exquisite specificity for millions of molecules, and lymphocytes that can recognize any molecule with highly diverse antigen receptors

Answer 2

Adaptive Immunity

Question 3

this is a type of adaptive immunity that is mediated by antibodies that recognize B cell receptors, it is the principle defense against microbes present outside of cells, antibodies bind to microbes to trigger immune response

Answer 3

humoral immunity

• produces antigen specific antibodies

Question 4

this type of adaptive immunity includes T cells that can only recognize peptide antigens and trigger apoptosis of infected cells

Answer 4

Cell-mediated immunity

Question 5

What are the 4 major immune functions of Antibodies?

Answer 5

[N.0. F*uck Antibodies]

1. Neutralization
2. Opsonization
3. Fixation of Complement
4. Antibody Dependent Cellular Cytotoxicity (ADDC)

Question 6

What is Neutralization used by antibodies to fight infection?

Answer 6

neutralization is when antibodies neutralized viruses and toxins by directly blocking their functions

Question 7

this process involves a coating of a pathogen with something more palatable to be eaten (phagotocized) such as antibodies, which get recognized by a receptor on phocytes to be ingested

Answer 7

Opsonization

Question 8

Explain Fixation of Complement used by antibodies to fight infection.

Answer 8

Antibodies will coat a microbe that is infected so that it could be recognized by the complement proteins.
Complement proteins then come in to put a dagger in the microbe - makine it pourous and killing it via lysis

Question 9

Explain the process of ADDC - antibody funciton to kill microbes.

Answer 9

ADDC is used when we have a virally infected cell.
Anibodies recognize the cell when they see a spike protein on its surface and bind to it.
this binding initiates Natural killer cells to come to the infected cell and kill it via apoptosis

Question 10

Antibodies have a unique structure and consist of many different classes. Describe the basic structure of antibodies: 
shape 
# and type of chains
constant and variable regions
name of arms and tail 
# of varibale domains 
# fingers

Answer 10

Y shaped protein
2 heavy chains 2 light chains
constant region is the tail (Fc)
variable region is the 2 arms (Fab) 
each arm has 4 variable domains 
each heavy chain and each light chain has 3 fingers which form the antigen binding sites 
* so 6 fingers on each arm

Question 11

this is the part of the antibody that binds to specific antigens

Answer 11

complementary determining regions (CDRs)

or hyperavailable regions (HV)

Question 12

this antibody class responds to allergies and worms. Y shape

Answer 12

IgE

Question 13

This antibody class is the foot soilder of the immune system. Y shape

Answer 13

IgG

Question 14

this antibody class is part of gut immunity and resistant to gut proteases 
it is made of dimer 2 Y antibodies

Answer 14

IgA

Question 15

this antibody class is made up of 5 antibodies (pentamer) has 10 binding sites so high binding availability but low affinity

Answer 15

igM

Question 16

This portion of the antibody is critical. It is the portion of the antibody that is bound to complement or is recognized by the receptors on phagocytes or on natural killer cells

Answer 16

Fc portion (tail)

Question 17

Antibodies are meant to protect us from disease. When could they actually harm us?

Answer 17

1. when they can recognize self antigens
2. when they form immune complexes with antigens in circulation, deposition in vessel walls - mediates damage (doesn’t require self antigens)

Question 18

Antibodies fight infections using neutralization, opsonization, fixation of complement and ADDC. When antibodies cause disease and damage to ourselves what proccesses do they use?

Answer 18

Antibodies fight infection in basically the same way they cause harm to self by instead using these processes when they start to recognize self antigens by mistake.

1. neutralization
2. opsonization
3. fixation of complement
4. inflammation –> complement activation +opsonization
   **• antibodies bind to self antigens on surface of epithelial cells, complement can bind to antibodies and get activated, C5a & C3a get produced (inflammatory) they bind to blood vessel wall, leads to movement of leukocytes outside of blood
   • neutrophils can bind to the antibodies- cannot eat the cell though (‘Frusterated phagocytosis”) - so it releases toxic granules which lead to damage and killing of epithelial cells