Complement System

Presenter: Dr. Karthikeyan P

Moderator: Dr. T.K. Mishra

Overview

• Discovery , characteristics of complement system

• Complement components and denomination

• Activation of the complement system—three pathways: classical pathway, Lectin pathway, alternative pathway - Comparison of three pathways

• Regulation of the activation of the complement system: self-regulation and roles of the regulatory factor

• Complement receptors: components, distribution, and functions

• Complement system in disease

History

Lectin pathway

Ficolin - structure

Alternate pathway

Alternative tick over pathway

Alternative properdin pathway

Alternative protease-activated pathway

• Inflammation and coagulation goes hand in hand.

• Thrombin cleaves C3

Classical pathway

• Why soluble antibodies can’t activate complements ?

• Which antibody is effective in complement activation and why ?

Classical Pathway Initiation

Common Terminal pathway

MAC

Review

Regulation of complement system

Complement receptors do effector function and regulation

• Complements in cell signalling

Anaphylotoxins

Complement system as a tool of diagnosis

• SLE low C3 and C4

• MPGN low C3, but normal C4

• Terminal complement deficiency low C5, C6, C7, C8, C9

• Properdin deficiency is an X-linked disorder that also causes susceptibility

to neisserial infections.

• C1-inhibitor deficiency or hereditary angioedema low C4 with normal

C1 and C3 levels

Complement system as a therapeutic target

• Purified C1 esterase inhibitor

• Ecluzimab in PNH

Complement system as a therapeutic target