Immune Complex Disease

Question 1

Hypersensitivity type I

Answer 1

Allergies and asthma

Question 2

Hypersensitivity type II

Answer 2

diseases caused by antibodies, i.e. immune throbocytopenia

Question 3

Hypersensitivity type III

Answer 3

diseases caused by antigen/antibody complexes, i.e. lupus erythematosus

Question 4

hypersensitivity type IV

Answer 4

diseases associated with “delayed hypersensitivity or TIMMI

Question 5

formation of an Immune complex depends on

Answer 5

the source and intensity of antigen exposure
The rate of IC formation is the balance between antigen exposure, Ag/Ab binding(avidity, valence), disposal by neutrophil catabolism and transport to distant disposal sites.
the vigor of the B cell response to the antigen-gender variability, TLR and MHC genes

Question 6

what two inflammatory amplifying systems can an IC activate

Answer 6

FcR crosslinking and activation and
complement via the classic or direct pathway
both mobilize neutrophils to the site of infection

Question 7

The vigor of IC formation

Answer 7

based on characteristics of antigen and how they interact with host factors such as fender, age and MHC and other “immune” related genetic loci of the host

Question 8

antigen bound to IgG binds

Answer 8

Fc(gamma)R on monocytes and neutrophils. this is an important interaction that mediates an inflammatory response

Question 9

ICs can be eliminated by

Answer 9

1. effective neutrophil destruction of antigen-reduces the amount of antigen at the inflammation site
2. catabolism by neutrophils and monocytes
3. Transport via CR1 receptors on erythrocytes to the liver for disposal

Question 10

CR1

Answer 10

receptor for C3b on all peripheral blood cells except platlets. Binds C3b and converts it to iC3b, transports IC to liver for disposal or sleep for B-cell activation

Question 11

if IC formation exceeds its disposal

Answer 11

pathologic inflammation either local or systemic can result (

Question 12

causes of production exceeding disposal of ICs

Answer 12

intensity and duration of the antigenic stimulus and impaired disposal(usually secondary to increased production of complexes)

Question 13

How do immune complexes cause inflammation

Answer 13

FcR cross-linking

Question 14

FcR crosslinking results in

Answer 14

activates neutrophils and macrophages
causes release of IL8 and other proinflammatory cytokines that recruit more inflammatory cell to the area
Destroys underlying vascular architecture and tissue damage

Question 15

Arthus Reaction

Answer 15

large #s of Ab’s already present when the antigen is introduced (usually by revaccination) causes formation of immune complexes so quickly that the system of removal by RBC is immediately overwhelmed. The ICs cause mass neutrophil activation by binding C3bR and FcR which triggers release of IL-8. Causes pain, swelling, and redness at injection site

Question 16

treatment of IC disease

Answer 16

Eliminate the antigen-drainage of an abcess, antibiotics
Inhibit antibody formation- can be dangerous
Suppress inflammation- also can be dangerous

Question 17

Function of IC delivered to the spleen and lymphoid tissue

Answer 17

strongly stimulate antibody production (these are NOT disposal sites like the liver)

Question 18

Crosslinking of FcRs on B-cells

Answer 18

tells the B-cells that there is enough Ab present and to stop producing more Ab (inhibitory signal)

Question 19

ITAM

Answer 19

Immunoreceptor tyrosise-based activation motif (ITAM)- triggered by the binding of IgG-IC to an Fc(gamma)R on a macrophage, monocyte, neutrophil, or DC. - results in increased phagocytosis. The receptor has high affinity and can therefore be activated by small amounts of IC

Question 20

ITIM

Answer 20

immunoreceptor based tyroside inhibitory motif (ITIM)- triggered by binding of IgG-IC to a Fc(gamma)R on a B-cell which inhibits B-cell proliferation and Ab formation. The receptor is low affinity and therefore needs a lot of ICs to become bound.

Question 21

How do we prevent Anti-Rh IgG from causing problems during pregnancy

Answer 21

Give the mother Anti-Rh IgG so that it binds the fetal RBC and the complexes bind B-cells turning off their response so that they do not make anti-Rh IgG (bc they think they already made enough)

Question 22

what would giving Anti-Rh-IgM do

Answer 22

activating signal- not inhibitory maybe do something with Tregs