The Complement System

Complement component C3 is cleaved by

• C3b

• C3bBb

• Factor B

• Factor D

The membrane attack complex in the complement pathway consists of

• C3b3b,Bb

• Colicins

• C5b,6,7,8,9

• Properdin

Complement componenet C3b

• directly injures bacteria

• is an anaphylatoxin

• opsonizes bacteria

• is the inactive form of C3

A complement component that is strongly chemo-tactic for neutrophils is

• C5a

• C3b

• C5b

• C9

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

• C1s

• C1q

• C9

• C3b

Several of the complement components are

• Antibodies

• cytokines

• Enzymes

• Hormones

The classical and alternative pathways meet at complement component

• C3

• C4

• C4b

• C5

One principal function of complement is to

• cross-links allergens

• phagocytize antigens

• bind antibodies attached to cell surfaces and to lyse these cells

• mediate release of histamine

The major role of the complement system is to work in conjunction with

• antibodies lyse cells via the C8 and C9 components

• antibodies lyse cells via the perforin molecules

• antibodies to opsonoze the cells

• T-cell receptor for production of lymphokines

Complement fixation

• Can be modified by the cholera toxin

• has intrinsic guanylate cyclase activity

• is an effector function of IgG and IgM following antigen binding

• can be desensitized by phosphorylation