the immune system

IMMUNE SYSTEM
Dr.Baha, H. AL-Amiedi
Ph.D.Microbiology
pImmune system :The Immune system comprise a network cells with each other cooperates directly to reach the effectors mechanism. and defense the body .against invaders , back to the 1 960 the immune system has been structurally and functionally confined to lymphoid organs .Recently however immune system may be of six component as in the following
. genetic component
. Haemopietic component
. Reticulo endothelial component
. complement component
. Lymphoid component
. mucosal component
genetic component: The immune system structures &functions are encoded by set of genes like control Immune response, GVHR immunoglobulin synthesis and The genes of MHC system involved in rejection of foreign tissue from a region known as the Major histocompatability complex (MHC) that contain several Polymorphic genes which expressed on the surface of all nucleated cells consist of two classes (class I and class II) .These act as peptide receptors and are important in Antigen presentation after processing the Antigen .These epitopes peptides bind to MHC molecules and present on the cell surface of antigen presenting cells like macrophage, dendric cells
Class I + epitopes peptide(APC)------- recognized by CD-8 T- Cell
( Intracellular infection )
Class II —epitopes peptide(APC) ------- recognized by CD-4 T- Cell
( Extracelluler infection )




Reticuloendothelial system: it s a System of cells and tissues whose function include principally phagocytosis and degradation and antigen presentation on the surface of the cells which including fixed macrophage and Circulation in blood. It is filter particular matter from blood. The cells of Reticuloendothelial system organized into dense sheet and fibers form sructura1 matrix e f spleen . bone marrow and lymph nodes
The cells are mononuclear leukocytes in blood in liver is kuppfar cells in spleen is denderitic cells in lung is alveolar cells… ect.
Haemopietic component:
bacteria it is large of lymphoid cells in blood (monocytes) they are produced by bone marrow .tissue macrophages are denderic cells in spleen alveolar cells in lung…. etc
Macrophages have function phagocytosis for the invading microbes.
Microphages are leukocytes of blood:
1. Neutrophil active phagocytic in m acute inflammation.
2. Eosinphils are phagocytic in condition like allergic inflammation, parasitic inflammation
3. Basophils cells will release of. pharmacologically active agents in anaphylactic and a topic allergy.
The Complement system
A plasma protein with 25 fraction these protein heat sensitive at 56 C for 30 minutes , the chemical structure of complement is polypeptide chains interconnected by disulfide bound.
The complement system plays a major role in host defense and the inflammatory process. The complement component synthesized in liver , spleen as well as enterocytes with 25 fractions. Nine fraction of which are involve in complement pathways which act as sequential manner and can be activated or inhibited , properdin is important on first exposure to Microorganism (first Immune Response)
Complement classical pathway in second exposure to microorganism (second immune response) complement defect associated with disease condition, Activators of complement system are of two types immunological &non-.immunology ,also complement system regulated
with inhibition factors.
Classical complement system pathway: The activation of this is
1) Antigen -Antibody.
2) Non - Immunological such as C-Reactive protein and staphylococus
Staphylococcus aureus protein A.
Alternative (properdine) Complement system pathway
1.The immunological activator lgG, IgA molecules
2. Non - Immunological Activator,
a. Lipopoly saccharide.
b. Copra, Venum factor.


The Mechanism of cell lyses with complement when fraction of complement system binding with the cell surface of cell. in present of’ antigen & Antibody it will non - equilibrium in permeability of cell wall non - equilibrium in protein synthesis process of hole in cells.
Non - equilibrium in metabolic of cells presence of hole in cell
wall and that will lead to lyses of cells
the function of complement system:
The complement play a wide range of biologial activites when activated:
1-Mediated Antigen-Antibody Reaction
2-Mediated inflammatory response
3-Facilitate phagocytosis.
4-Facilitate blood coagulation
5-Neutralize viruses effect & the effect of bacterial LPS
6-Play a role in the non-specific resistance to microbial infection
7-Associated with immune distraction - of blood cellular component
1.The immunological activator lgG, IgA molecules
Complement fixation test : This is very sensitive is very
sensitive test and is capable of detection Antigen & Antibody it is used
for serological diagnosis with principle : The ability of Antigen – Antibody
complex to fix complement used for diagnosis of disease
1. Spirochaetal disease e.g Sphilis (wasserman reaction)
2. Rickettsial disease e.g typhus fever.
3. Viral disease like lymphogranuloma venerum
4. Parasitic disease e.g kala-azar, hydatid cyst, amoebiasis