Antigen Flashcards
Any molecular structure that when introduced is capable of Antibody production.
ANTIGENS
- Can elicit the immune system to produce antibodies
- Can be microorganism, pathogen, foreign substances, etc.
ANTIGENS
responsible for the molecular weight of the antigen; the molecular weight of an antigen can be expressed as _______
Carrier Portion; daltons
determines the specificity of the antigen; responsible for the specific antibody production and can be based on the nature of the antigen
Epitope or Determinant
The entire microbial cell is the carrier portion of the antigen. The specific structures on the membrane of the cell are the epitopes. The epitopes on the surface would determine the specific antibody that would interact with the _____?
bacillus
inherent ability of a substance to induce immune response resulting in the formation of immune lymphocytes or antibodies
IMMUNOGENECITY
the immunogen must be recognized as foreign or non-self to induce immune response
FOREIGNESS
self-antigen; derived from the person’s body
Autoantigen
derived from other individuals of the same species
Alloantigen
Example of Alloantigen
Blood cells of donors
derived from other species; can derived from animals or nonhuman sources; most foreign to humans
Heteroantigen
a type of heteroantigen that is produced from unrelated plants or animals that can induce a common or similar immune response
Heterophile antigen
is also known as tissue transplant
Graft
obtained from the patient’s own body
Autograft
Example of Autograft
Patients who had second- or thirddegree burn
obtained from identical individuals (identical twins)
Isograft/ Syngraft
obtained from non-identical individuals of the same species; most common graft transplanted
Allograft
Example of Allograft
Kidney, Blood
commonly transfused tissue
Blood
obtained from other species
Heterograft/ Xenograft
Example of Heterograft/ Xenograft
Other mammals or laboratory animals (pig’s heart)
Minimum molecular weight for an antigen/ substance to induce immune response:
at least 10,000 daltons of molecular weight or
higher
If less than 10, 000 daltons, the antigen is
considered as _____ (incomplete antingen)
thus, incapable to induce an immune
response due to its small size
hapten
(30, 000 to 60, 000 daltons); considered as a good antigen
Albumin
(100,000 to million daltons); excellent antigen because it is highly complex type
Hemocyanin
the best and strongest antigen; highly stable because of the peptide bonds present which makes it circulate longer in the body
Proteins
In the circulation, if the antigen could last longer in the circulation, that would make an antigen highly immunogenic. The longer it stays in the circulation, the longer the exposure of the antigen in the immune system leading to a greater chance of immune response.
Proteins
Example of Polysaccharides
Endotoxin, pneumococcal capsule
like ABO, Rh antigens
Glycoproteins
Example of Polypeptide
Insulin
least immunogenic
Nucleic Acid, Lipids and Amino Acids
the ability to react specifically with the antibody
or cell that caused it to be produced
ANTIGENICITY/ SPECIFICITY
based on the epitope present on the antigen surface
Specificity
an incomplete antigen; not immunogenic by itself; if coupled with a carrier protein, hapten can elicit immune response since molecular weight will be increased and hapten structure will be stabilized
Hapten
Common carrier protein
Albumin
defined as any substance that can induce an immune response; antigen
Immunogen
a special class of immunogen that induces hypersensitivity reactions specifically Type 1 hypersensitivity reaction; cause reaction to some people but not all
Allergen
substances added to an immunogen to enhance immune response
Adjuvants
longer stay in circulation, increases the chance to be recognized by immune cells (WBCs), activating immune system
Prolongs the retention time of the immunogen in the body
the bigger substance, the more immunogenic and becomes easily recognized
Increases the effective size of immunogen
increased production of immunocompetent WBC
Stimulates the influx of macrophage and/or lymphocytes
Examples of Adjuvants
✓ CFA (Complete Freunds Adjuvants)
✓ LPS (Lipopolysaccharide)
✓ Aluminum Adjuvants
composed of water in oil emulsion of Mycobacterium butyricum or Bordetella pertussis culture
CFA (Complete Freunds Adjuvants)
more clinically/commonly used
Aluminum Adjuvants
antigen that induces an antibody and reacts specifically with it
Homologous antigen
cross reaction; antigen reacts with antibody. It did not induce for its production
Heterogenous antigen
the strength of attraction between an epitope and the antigen combining site (Fab portion)
of the antibody
Affinity
the sum of interaction/the strength of interaction between complex antigens and antibodies
Avidity
measures the strength of attraction/interaction
AFFINITY & AVIDITY
involves simple interaction (single epitope + Fab portion)
Affinity
involves multiple epitopes are interacting with antibodies
Avidity
