Lecture 2 A
Medical Immunology Techniques
Dr. Sheng Xia
xiasheng1519@163.com
Department of Immunology
Jiangsu University
Antigen, antibody
and
Cytokine in Diseases
Antigen
• Antigen: a substance that stimulates antibody
formation and has the ability to bind to an
antibody.
• Antigen contain structures recognized as
foreign by the immune system, which are
called antigenic determinant, or epitope.
• Epitope can be re-act specifically with an
antibody or T lymphocyte receptor (TCR).
** Tolerogen
Allergen
Antigen
Important antigen in clinic
Pathogens and their products
• Structure of pathogens:
surface antigen; somatic antigen; Flagellar antigen; pillus
antigen
Important antigen in clinic
Pathogens and their products
• Structure of pathogens:
surface antigen; somatic antigen; Flagellar antigen; pillus
antigen
Important antigen in clinic
Pathogens and their products
•
Structure of pathogens:
surface antigen; somatic antigen; Flagellar antigen; pillus antigen
Products of pathogen: Toxin
•
Serum
•
Exotoxin
In vivo
Anti-toxin
Immunization
Fixation in
formalin
Toxoid（loss of toxicity, keep antigenicity ）
Important antigen in clinic
How to detect antigens of pathogen in
patients with immunological methods?
EXPAMLE: HBV infection
Immunoglobulin and Antibody
Immunoglobulin (Ig): It refers to all globulins that possess the
bioactivity of Ab or a similar structure to Ab
Antibody (Ab): a type of glycoprotein molecule, produced by B
cells that bind antigens often with a high degree of
specificity 。
Therefore, all Abs belong to Igs,
but not all Igs possess the functions of Abs.
Structure of Immunoglobulin
Four polypeptide chains
2 identical heavy chains
2 identical light chains
The 4 polypeptide chains
are joined by S-S bonds.
intra-chain disulfide bonds (S-S)
Two terminal ends
“N” terminal end
“C” terminal end
Two regions
variable regions
constant region
N-terminal end