Antibody Function

Question 1

Define epitope

Answer 1

• Part of Ab that interacts with the Ag
• Usually 10-20 AAs long
• AKA: antigenic determinant
• Proteins have several epitopes (all bind to different Abs)

Question 2

Define antibody valence

Answer 2

• Refers to many antigenic determinants that an individual Ab molecule can bind
• At least two (divalent) or sometimes more (multivalent)

Question 3

Define affinity

Answer 3

• Strength with which an Ab molecule binds to an epitope

Question 4

Define precipitation

Answer 4

• Large immune complexes that form at or near equivalence
• Tend to become insoluble and precipitate!
• Ag is a molecule

Question 5

Define agglutination

Answer 5

• Similar to precipation

- Except ag is a cell or cell-sized

Question 6

Describe IgG in terms of passage across the placenta, ability to activate complement by the classical pathway, ability to activate complement by the alternative pathway, involvement in allergic diseases, “first line of defense”, most resistant to enzymatic digestion

Answer 6

• Most abundant Ig in blood
• Only Ig that passes the placenta (mom—>fetus) — requires active transport
• comes after IgM after 1ry IZ — stay higher and last longer though
• plasma life = 3 weeks

Question 7

Describe IgM in terms of passage across the placenta, ability to activate complement by the classical pathway, ability to activate complement by the alternative pathway, involvement in allergic diseases, “first line of defense”, most resistant to enzymatic digestion

Answer 7

a

Question 8

Describe IgA in terms of passage across the placenta, ability to activate complement by the classical pathway, ability to activate complement by the alternative pathway, involvement in allergic diseases, “first line of defense”, most resistant to enzymatic digestion

Answer 8

a

Question 9

Describe IgD in terms of passage across the placenta, ability to activate complement by the classical pathway, ability to activate complement by the alternative pathway, involvement in allergic diseases, “first line of defense”, most resistant to enzymatic digestion

Answer 9

a

Question 10

Describe IgE in terms of passage across the placenta, ability to activate complement by the classical pathway, ability to activate complement by the alternative pathway, involvement in allergic diseases, “first line of defense”, most resistant to enzymatic digestion

Answer 10

a

Question 11

Sketch the immune complexes obtained in antigen or antibody excess, and at equivalence, using Y as Ab and + as antigen

Answer 11

a

Question 12

Discuss why a line of precipitate may form in agar gel when antigen and Ab diffuse towards each other

Answer 12

a

Question 13

Describe precipitation in terms of the nature of the antigens involved, and sensitivity of the tests.

Answer 13

a

Question 14

Describe agglutination in terms of the nature of the antigens involved, and sensitivity of the tests.

Answer 14

a