Immune
Respones
Dr. Baha. Hamdi. AI-Amiedie
Ph. D.Microbiology
PRIMARY &SECONDARY
IMMUNE RESPONSE
Primary 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 . lmmunogen
injected 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 Bcells to produce large amount of antibody
( mainly IgG). This response is seen with Bcell and DTH T-Cell. An anemnestic
response 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 Antibodies
Are glycoprotein present in the gamma- 
globulin fraction of serum. which make 2025 % 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 Reaction
The 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’s

test 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 