Immune ResponesDr. Baha. Hamdi. AI-Amiedie

Ph. D.Microbiology

PRIMARY &SECONDARY

IMMUNE RESPONSEPrimary Immune Response:

This is the first interaction between the antigen and B-cells ,the B-cells will differentiate and become memory cells for future exposure or become mature plasma cells and produce antibodies .the antibody classes strat with IgM, and described as Antigen specific response . lmmunogeninjected intramuscular has greater immune response than an immunogen taken orally . A 25-Year old will have a greater immune

response than if it given to child.

Secondary Immune Response:

This is anamestic response . It is also known for response of booster shot , it cause a rapid proliferation and differentiation of B-cells to produce large amount of antibody ( mainly IgG). This response is seen with B-cell and DTH T-Cell. An anemnesticresponse is faster, more specific and longer lasting than primary immune response.

The antigen type is in these responses is B-dependent-Antigen

Primary & secondary immune

resoponse

Lymph node

factor influencing Antibody production:

.1-Age

.2-Nutritional status

3-Route of administration

4-Size and Number of doses

5-Multiple antigens

.6-Adjuvant

.7-Immunosuppressive agent.

Imunoglobuline

Or AntibodiesAre glycoprotein present in the gamma-

globulin fraction of serum. which make 20-

25 % of serum protein Immunoglobulin

generally natural present in blood without

previous antigenic stimulation However

antibody are produce

specifically by activated B-cell( plasma cell )

after antigenic stimulation . Thus all

antibodies are Immunoglobulin while no all

Immunoglobulin are antibody

Electrophoresis Assay

The characteristic of antibody are

1-glycoprotein in nature.

2-specific to antigen induce them.

.3-React specifically with their

own antigen

Antibody are distributed in serum, body

fluid, Urine ,Saliva , Ear wax and tears.

CLASSES OF ANTIBODIES

The antibody molecule are found to be of different classes , the classification depend on :

1-The molecular size

2-Natur of carbohydrate,

3-Amino acid sequence.

The classes of Antibodies are IgM, IgG, IgE & IgD.

The difference between these Classes depend on the type of heavy chain in each molecule, Immunoglobulin , the term immunoglobulin is structural & chemical concept while antibody is biological and function concept.

The basic structure of antibody

antibody are made up of one or more units (monomers) comprising four polypeptides which are:

1-two identical light chain (I.C) consist of 214 amino acid, 106 amino acid respect the constant region of molecule while variable region consist of 108 amino acid for Kappa & Lambda

2-two identical heavy chain (HC) consist of 440 amino acid, residues 322 amino acid occur in constant region (CH). 118 amino acid in the variable region (VH)

Basic Structure of Antibody

There are 5 Classes of (HC) Heavy

chain content of five Classes of

lmmunoglobulines:

1-(Gamma) or lgG

2-(Mu) or lgM

3-(Alpha) or lgA

4-(Epsilon) or lgE

5-(Dalta) or IgD

The variable region in both heavy chain

(HC) and light chain (LC) are consist the

antigen combination sit.

Fab : it is amino acid terminal half of

heavy chain & light, it act as Antigen

binding fragment .

Fc: It is carboxyl terminal half of

heavy chain & determine biological

properties of Immunoglobulin

Mono, di & pentameric of antibody

These chains are connected to form

Y- shaped molecules:

1- IgM is a pentamer of the basic

structure

2-IgA is usually a dimer

3- lgG, IgD & lgE are monomeric

Atigen and Antibody ReactionThe following are the important tests based on

antigen -Antibody reactions

• Agglutination

• Precipitation

• Redioimmunoassay

• ELISA

• Immune fluorescence

• Neutralization

• Haemagglutination

• Antiglobulin test ( comb’s test )

• Complement fixation test. and other tests using complement system

Precipitation

The antigen -Anti body complex is not. found firmly together and may dissociate spontaneously unless PH, salt concentration and temperature are properly the antigen — antibody complex forms insoluble Precipitate.

The use of precipitation reaction in:

1-identification of bacteria, example detection of group Specific polysaccharides substance in streptococci in Lancefield group.

2-Identification of antigen component of bacteria in infected animals tissue. Example bai1lus anthracis(Ascoli test)

3-Standardization of toxin and anti- toxins.

4-Demonstration of antibody in serum, as kahn’stest for the diagnosis of syphilis.

Lattic hypothesise

Lattic hypothesis

is multivalent antigens combine with bivalent antibody in varying proportions , depending antigen antibody ratio in reaction mixture precipitation result When large lattice is formed consisting of alternating antigen and antibody molecules in the zone of equivalence.

precipitation is maximum when optimal

proportion of antibody combine precipitation can be produced in solutions or in semisolid (agar gel) medium, precipitation in solution can be shown by adding these two on a slide and mixing well or in small narrow tubes.

Latex Agglutination:

This performed with microscopic latex

( really polystyrene) which have been

coated with specific antibody when this

beads mixed with fluid consist specific

Antigen they bind to the antigen

agglutination and forming visible

precipitation

Cellular Immune Response:

The term cell mediated immunity refers to the specific immune responses that do not involve antibodies, induction of cell mediated immune response (CMI) ,The T-cell recognize Antigen through a surface molecule termed the T-cell receptor (TCR) ,Each T-cell possesses a different (TCR) to allow it to recognize a different antigen . specifically sensitizing T-lymphocytes comes against the antigen. When sensitized T-cell comes in contact with antigen determinant (epitopes) after the enzymatically degraded antigen into small peptides (epitopes)

which binding to class l or class ll and

transport to the cell surface; Class l pathway

activated CD 8 (Cytotoxic) T-cell

While Class ll pathway activated CD4 T-Cell

(TH2 &TH1 Cells) by the function of Antigen

Presenting Cell (APC) ,so T-cell under goes

blast transformation and clonal proliferations

selectively in paracortical areas of lymph

nodes.

Function of antigen presentation cell

lymphokines

lymphokines: material required as

secreted proteins from the activated T-cell

, These Lymphokine have several biological

function

Agglutination or latex test

1-Effect on macrophage :

: This Lymphokine is function is covered

out by the following:

a-Macrophage inhibition Factor (MIF)

b-Macrophage aggregation Factor(MAF)

c-Macrophage chemotactic Factor (MCF)

2-Effect on Lymphocytes:

The role is done by:

a-Blastogenic factor (BF)

b-Potentiation factor (PF)

c-Cell co-operation factor (CE).

3-Effect on granulocyte: •.

a-Inhibition factor (IF)

b-Chemotactic factor(CF)

4-Effect on tissue cultur:

a-Lymphotoxin

b-Proliferation inhibition factor (PIF)

c-Interferon