Complement System

Complement component C3 is cleaved by:

• C3b

• C3bBb

• Factor B

• Factor H

The membrane attack complex in the complement pathway consists of:

• C3b3b,Bb

• C5b,6,7,8,9

• Properdin

• C4b,2a

Complement component C3b:

• Directly injures bacteria.

• Is an anaphylatoxin.

• Is the inactive form of C3.

• Opsonizes bacteria.

The initial complement component that is bound by complement-fixing antibodies is:

• C1q

• C1s

• C3b

• C9

Several of the complement components are:

• Antibodies

• Cytokines

• Enzymes

• Glycolipids

The classical and alternative pathways meet at complement component:

• C3

• C4

• C4b

• C5

The deficiency of the complement component factor D and properdin lead to recurrent bacterial infection. Which of the following pathway is affected in this condition?

• Alternative pathway

• Classical pathway

• Lectin binding pathway

• None of the above

Which of the complement receptor activate phagocytosis by binding to C3b & C4b coated particles?

• CR1

• CR2

• CR3

• CR4

Which of the following component of complement proteins enhances inflammation (anaphylatoxin)?

• C3a

• C5a

• Both of the above

• None of the above

Certain microorganisms such as Salmonella, Listeria, Neisseria, Cryptococcus consist of specific carbohydrate moieties on the surface antigen that activate _______________________.

• Alternative Pathway

• Classical Pathway

• Lectin Binding Pathway

• All of the above