Complement System
Series of 20 ptn synthesized in liver, heat labile ptn inactivated
by heating serum at 56c for 30 minutes.
Activation of complement system by
1-Immunological molecules.
2-non Immunological molecules like bacterial lipopoly
saccharide.
Pathways of complement system activation
1-the classical pathway
2-ulternative pathway
3-lectin pathway
Biological effects of complement system
1-opsonization
2-chemotaxis
3-anaphy latoxin
4-cytolysis
5-Enhan cement of antibody production
Regulation of complement system
1-C1 estrase inhibitor regulates the classical pathway of
complement system.
2-the ulternative pathway is regulated by binding factor H to
C3b forming acomplex which is cleaved by factor I leading to
reduction in the amount of C5 convertase.
3-protection of cell from lysis by membrane attach complex
occur by decay accelerating factor  destabilization of C3 and
C5 convertase.
Medical Application
1-inherited or Aquired difficiency of C5 –C8 neisseria
bacteremia.
2-inherited difficiency of C1 estrase inhibitor hereditory
Angio oedema.
3-Aquired difficiency of decay accelerating factor paroxysmal
nocturnal hemoglobinurea.
4-In blood transfusion mismatches hemolysis occur due to
complement activation.
5-in SLE complement level is low due to its consumption.
6-inliver cirrhosis complement level in low due to inability of
liver to synthesize sufficient amount of complement.
Tolerance and Autoimmune disease
The lack of specific immune response to certain antigen in
afully immune competent individual.
Types of tolerance
1-naturally acquired tolerance (neonatal) tolerance. failure of
this type of tolerance  Autoimmune disease.
2-Induced tolerance. this type of tolerance used for treatment
of autoimmune disease and Allergic conditions.
Factors affect the induction of tolerance
1-neonatal immaturity of the host.
2-types of cells B or T lymphocyte.
3-Dose of toleragen.
4- complexity of toleragen.
5-Immuno suppressive therapy.
6-persistance of toleragen.
Auto Immune Diseases
They are disease that results from an Immune response of the
Individual towards his own tissus occer in female more than
male.
Etiology
1-Release of sequestered Ag.
2-increase activity of self reactive T helper lymphocyte.
3-by pass T helper cell activity.
4-genetic predisposition.
5-increase expression of class II MHC molecules.
6-thymus defect.
7-break down of suppressor mechanism.
Stimulatory factors in causation of Autoimmune
disease
1-enviromental factors.
2-genetic factors.
3-hormonal factors.
4-Age factor.