Hd (04-20-06) Complement Ii

Front 1

Which receptors are involved in opsonization?

Back 1

CR1, CR3, CR4.
They bind to iC3b (or in the case of CR1, C3b) to recruit macrophages, monocytes, leukocytes, B-cells, and FDC's.

Front 2

Which receptors are involved in immune complex clearance?

Back 2

CR1.
They bind to C3b and iC3b and allow RBC's to transport immune complexes to the liver.

Front 3

Which receptors are involved in inflammation - endothelial activation?

Back 3

C5a-R, C3a-R.
They recruit endothelial cells and mast cells.

Front 4

Which receptors are involved in inflammation - recruitment and activation of phagocytes?

Back 4

C5a-R.
They recruit phagocytes.

Front 5

Which receptors are involved in regulation of the adaptive immune response by binding to B-cell co-receptors?

Back 5

CR2.
They bind to C3d, iC3b, C3dg, which are co-stimulatory for activating B-cells.

Front 6

How is complement regulated by decay?

Back 6

Spontaneous decay will degrade the activating component of complement, usually by hydrolysis. This prevents unbound complement from activating and damaging cells unnecessarily.
Free C3b will undergo spontaneous decay almost immediately after being released.

Front 7

How is complement regulated by the classical pathway?

Back 7

The C1INH protein will cause dissociation of the C1-q-r-s complex by dissociating C1r and C1s from the activated C1 complex.

Front 8

How does DAF regulate the complement reaction?

Back 8

Binds either C4b (classical) or C3b (alternative), inhibiting both complement pathways.
(No cofactor is required).

Front 9

How does MCP regulate the complement reaction?

Back 9

Binds either C4b (classical) or C3b (alternative), inhibiting both complement pathways.
(Cofactor I is required).

Front 10

How does CR1 regulate the complement reaction?

Back 10

Binds either C4b (classical) or C3b (alternative), inhibiting both complement pathways.
(Cofactor I is required).

Front 11

How does C4BP regulate the complement reaction?

Back 11

Binds only to C4b to inhibit the classical pathway.
(Requires cofactor I).

Front 12

How does Factor H regulate the complement pathway?

Back 12

Binds only to C3b (competitively with Factor B) to inhibit the alternative pathway.
(Requires cofactor I).

Front 13

How does Properdin (Factor P) regulate the complement pathway?

Back 13

It is a positive regulator that enhances C3bBb activity in the alternative pathway by stabilizing it and increasing its half-life.

Front 14

How is MAC formation regulated in the complement pathway?

Back 14

CD59 (protectin) prevents the last phase of assembly of C5b-9 at the final C8/C9 stage.

Front 15

What is hereditary angioedema?

Back 15

A C1INH deficiency that leads to increased spontaneous complement activation, including the formation of anaphylatoxins and other complement products. Result is edema, abdominal pain, and swelling caused by stress.
Treatment: C1INH infusion therapy.

Front 16

What is paroxysmal nocturnal hemoglobinuria (PNH)?

Back 16

A rare GPI (glycosyl-phosphatidylinositol) protein-linked deficiency, particularly DAF and protectin. All blood cells are susceptible to hemolysis by the complement pathway.

Front 17

What diseases are caused by Factor H and I deficiencies?

Back 17

Glomerulonephritis, and hemolytic uremic syndrome.

Front 18

What diseases are caused by DAF/MCP homologue deficiencies in mice?

Back 18

Increased loss of pregnancy in mice.

Front 19

Why does a C1, C2, or C4 deficiency increase the prevalence of autoimmune diseases?

Back 19

Complement typically binds to an apoptotic cell and assists in its removal. A deficiency in this pathway may prevent apoptotic cells from clearing, and result in re-presentation through APC's. This might break tolerance.

Front 20

What are some therapeutic approaches to complement disease?

Back 20

Block activated complement and introduce regulatory proteins.