Immunology 3: The antibody response and antibody effector mechanisms

Question 1

Roux & Yersin first showed what?

Answer 1

• 1888

- that a bacterium free filtrate of the diphtheria bacillus contained exotoxin

Question 2

What is an exotoxin?

Answer 2

poison shed/excreted by a pathogen

Question 3

Immunity can be developed to toxins by ____?

Answer 3

immunizing with a sublethal dose of the toxin (toxoid) treated in a way so it wasn’t toxic anymore
-heating/treating it with inactivating chemicals

Question 4

When blood was collected from an immune animal treated with a toxoid, what happened?

Answer 4

Blood would clot & cell-free yellow liquid that seperates (serum) inactivates the toxin

Question 5

Administration of immune serum to normal/unimmunized animals did what?

Answer 5

Conferred immunity to toxin i.e. resistance to normally lethal challenge of toxin

Question 6

Discovery of _____ led to recognition that ____ exist.

Answer 6

Passive transfer of immunity (i.e. giving serum from immune to normal animal); protective molecules are present in immune serums (ANTIBODIES)

Question 7

Molecules/substances antibodies specifically bind?

Answer 7

Antigens

Question 8

Von Behring and Kitasato first demonstrated protective role of antibodies via passive transfer of immunity how?

Answer 8

• 1890
• employed antibodies to poisonous tetanus toxin & had similar observations
• also did this with antibodies for diphtheria toxin

Question 9

Protective immunity shown to be due to ____.

Answer 9

presence of something in immune serum that was absent in normal serum

Question 10

Agglutinate

• definiton
• seen when?

Answer 10

immune system causes bacteria to clump together

-Charrin & Roger showed with pseudomonas in 1889

Question 11

Why does immune serum to a filtrate of bacterial cultures precipitate with the filtrate?

Answer 11

because bacteria produce soluble/filterable antibodies and immune serum has antibodies specific for these antibodies.

Question 12

Process by which precipitate is formed is called?

Answer 12

Precipitin reaction

• very specific!!! (lock & key)
• what generally happens when immune system is mixed with appropriate soluble antigen

Question 13

Effector mechanisms activated by ___.

Answer 13

Antibody molecules
-bind to antigen & call upon various mechanisms to attack the antigen they are bound to (i.e. they are adaptors connecting antigen to attacking machinery)

Question 14

“Attacking machinery” for antigens

Answer 14

• evolutionarily older than the immune system

- serves in innate resistance

Question 15

How do antibodies render mechanisms of innate resistance highly specific (by acting as an adaptor)?

Answer 15

• activation of complement
• enhancement of phagocytosis
• trigger acute inflammation

Question 16

Activation of complement (antibodies using mechanisms of innate resistance)

Answer 16

immune serum causes bacterial lysis to kill them

• this property is lost once immune serum is heated to 56 degrees celsius
• If heated serum is complemented with non-heated serum, can still lysis & kill bacteria (Bordet)

Question 17

How can the heated & non-heated immune serums still lysis (punch holes in bacterial membrane)?

Answer 17

• the heated serum provides heat-resistant specific recognition antibodies
• non-heated serum provides heat-liable non-specific compliment required to lysis bacteria
• example of antibodies using innate defence mechanisms to provide specific attack against something they bind

Question 18

Enhancement of phagocytosis (antibodies using mechanisms of innate resistance)

Answer 18

Serum has specific antibodies called OPSONINS that specifically enhance phagocytosis of antigen to which antibodies bind via acting as linking molecule (attach to both microbe & phagocyte, build bridge)

Question 19

Trigger acute inflammation (antibodies using mechanisms of innate resistance)

Answer 19

Histidine stored in granules of mast cells present in skin

• mast cells bind specific cytophilic (cell loving) antibodies
• when these cells bound to antibodies interact with appropriate antigen, discharge granule contents (histidine) causing acute/local inflammation

Question 20

How can someone determine if they have cytophilic antibodies for a particular antigen?

Answer 20

inject skin with small amount of an antigen & if local inflammation occurs w/in 20min, antibody molecules bound to mast cells exists
-person with a + acute skin reaction said to be allergic to this antigen & display an acute inflammatory reaction