Immunoglobulins

Question 1

What are immunoglobulins?

Answer 1

They are glycoproteins (sugar proteins)

Question 2

What are immunoglobulins used for?

Answer 2

Different functions

• Opsonize- immunoglobulins coat antigen (say bacteria) & mark it & get it phagocytized
• Neutralize- Can coat pathogen with antibodies & make it ineffective by taking up binding sites
• Activation of complement system- Antibody binds and activates complement system which introduces MAC which makes pores which destroys pathogen

Question 3

What do B cells secrete? What type of response?

Answer 3

• Immunoglobulins (Ig’s), they create immunoglobulins
• They make a lot of immunoglobulins
• But only one antigen type, one type of antibody specific to one antigen
• They have humoral response

Question 4

Structure of immunoglobulin/antibody

Answer 4

• 2 Heavy regions & 2 light regions
• held together by disulfide bonds
• Fab region (top half) binds antigens (specific to antigen). Determines antigen binding
• Fc region (bottom half) binds to receptors on cells

Question 5

Immediate response, acute infection

Answer 5

IgM

Question 6

Delayed response

Answer 6

IgG

Question 7

If we take blood sample from a patient and find IgG what does that mean?

Answer 7

It means they have been infected with the bug for awhile because the body takes awhile

Question 8

Function of IgG

Answer 8

• It does everything
• Main Ig in blood
• Activate complement system, create membrane attack complex MAC.
• Kill it
• Opsonize
• Neutralize

Question 9

What does IgM do?

Answer 9

• Immediate response
• Important structure (pentomeric) Fc region bound together in middle, Fab portions sticking out so it can bind many antigens (5)
• Great for agglutination because its huge
• Bind or fix complement
• Found on B cell surface

Question 10

IgA points

Answer 10

• Mucous membrane
• Gets passed from mother to baby through breast milk, baby receives passive immunity
  It coats:
• Saliva
• Gastric wall
• Intestinal mucosa
  Anywhere where there is mucous
• Structure: diameric & dimer
• Does not fix complement (activate membrane attack complex)

Question 11

What do the IgM & IgG have in common?

Answer 11

They both activate the complement system whereas the others do not

Question 12

IgD

Answer 12

• Found in monomeric state
• Found on B-cell surface
• Does not fix complement

Question 13

IgE

Answer 13

• Helminth (worm infection)
• Binds to helminth coat, this will signal to the eosinophils to attach to helminth & they will release contents which will kill the helminth
• Associated with mast cells & basophils
• Allergic allergies