Types Of Antigens Flashcards
: immune response against autoantigens.
• Autoimmune disease
Antigens that belong to the host.
AUTOANTIGEN
They are not capable of eliciting an immune response under normal circumstances.
Autoantigen
” Important to consider in tissue transplantation and
blood transfusions.
ALLOANTIGEN
They are different from the host’s antigens and are capable of eliciting an immune response.
ALLOANTIGEN
Come from other members of the host’s species.
ALLOANTIGEN
• For example, human blood group A and B antigens are related to bacterial polysaccharides.
HETEROANTIGEN
are a type of heteroantigen that exist in unrelated plants or animals.
Heterophile antigens
• Examples include antigens from other animals, plants, or microorganisms.
HETEROANTIGEN
• Come from a different species than the host.
HETEROANTIGEN
Effect of proteus vulgaris in blood typing
Proteus vulgaris is a type of bacteria that can be found in the environment, including soil and water.
Proteus vulgaris can interfere with blood typing by causing false reactions or autoagglutination, leading to inaccurate blood type results. Proper sample handling and testing are crucial to prevent and manage such interference.
No agglutination reaction.
Type A blood donated to a type A recipient does not cause an agglutination reaction… why?
Type A blood can be safely donated to a Type A recipient because both have the same A antigens, and the recipient’s immune system does not have antibodies (anti-B antibodies) against A antigens. This compatibility prevents agglutination reactions.
Agglutination reaction.
Type A blood donated to a type B recipient causes an agglutination reaction…why?
Type A blood causes an agglutination reaction in a Type B recipient because the recipient’s anti-A antibodies attack the A antigens on the donated red blood cells. This incompatible antigen-antibody interaction leads to clumping and potential destruction of the donor blood cells.
A mitogen is a substance that…
stimulates mitosis (cell division) in all T cells or all B cells, regardless of antigen specificity.
Mitogen for T cells
Phytohemagglutinin (PHA)
(red kidney bean)
Concanavalin (ConA)
(jack bean)
Mitogen for B and T cell
Pokeweed mitogen (PWM)
(pokeweed)
Mitogen for B cells
Lipopolysaccharide (LPS)
(Escherichia coli)
Microbial proteins that can act as potent T- cell mitogens.
SUPERANTIGENS
” Massive T-cell activation leads to a surge in cytokine release, resulting in a systemic inflammatory response known as…
toxic shock syndrome
• Generated within a cell
• Typically derived from viruses or intracellular bacteria that are actively replicating within the host cell.
ENDOGENOUS ANTIGENS
originate from outside the cell.
are taken up by specialized antigen-presenting cells (APCs), such as macrophages, dendritic cells, and B cells, through phagocytosis or endocytosis.
EXOGENOUS ANTIGENS
Most protein antigens are classified as…
T-dependent.
T-CELL DEPENDENT ANTIGENS…
Require T-cell help for B cells to mount an effective antibody response..
Steps in T-cell dependent antigens
Steps:
• Antigen presentation
• T-cell activation
• B-cell activation and differentiation
• Antibody production
These antigens typically possess repetitive structures (ex. those found in polysaccharides, lipopolysaccharides, and some polymeric proteins)
T-CELL INDEPENDENT ANTIGENS
Can activate B cells directly without the
TI-1 antigen need for T-cell help.
T-CELL INDEPENDENT ANTIGENS
• Two types of T-independent antigens:
Type 1
Type 2
primarily activated by dendritic cells and macrophages.
• Type 2 T cell independent
activated by binding to immunoglobulin receptors and other receptors, such as Toll-like receptors (TLRs).
Type 1 t-cell independent antigen
SEQUESTERED ANTIGENS
• A.k.a.
cryptic antigens
This concealment prevents the immune system from learning to tolerate these antigens, potentially leading to autoimmune reactions if they are later exposed.
SEQUESTERED ANTIGENS
• Self-antigens hidden from the immune system during its development.
SEQUESTERED ANTIGENS
Sequestered antigens in humor of eyes
sequestered antigens in the eye are hidden to protect the delicate structures from immune system attacks. If these hidden antigens are exposed due to injury or disease, it can trigger an immune response that might harm the eye.
Differentiate T-cell dependent and independent antigens
T-Cell Dependent Antigens:
Need T cells to help stimulate an immune response, leading to a stronger and longer-lasting response.
T-Cell Independent Antigens:
Can directly activate B cells without T-cell help, leading to a weaker and shorter-lived immune response.
M proteins as superantigens
M protein acts as a superantigen by directly stimulating a large number of T cells in a non-specific manner, bypassing the normal antigen processing and presentation.
This causes an exaggerated immune response that can lead to severe conditions like toxic shock syndrome.
