IM4: Adaptive immune response Flashcards
(21 cards)
Define antigen.
Foreign substance that induces an immune response in the body.
Define specificity.
Immune response is adapted to individual antigens.
Define adaptation.
Immune system functions only ib contact with an antigen & its quality & quantity can be modified.
Define memory.
Previous contact with antigen changes subsequent responses quantitatively & qualitatively.
B cell characteristics
Produce antibodies
Have antigen-specific receptors (BCR)
Have memory
Recognise large antigens
How do T cells recognise antigens?
Recognise antigenic peptides bound to MHC.
What are the subcategories of B cells?
CD4+ T cells
CD8+ T cells
What are CD4+ T cells?
They are the helper T cells that organise the immune response by secreting cytokines.
What are CD8+ T cells?
They are cytotoxic and involved in pathogen killing.
How are antigens recognised?
They bind to antigen-specific receptors on the surface of B/T cells.
How can BCR & TCR be modified?
Parts of the T/B cells that control receptors are mutated to modify the receptor’s affinity/avidity to the antigen.
What allows specificity?
Gene rearrangement of specific receptors
Selection of receptors in individual animals during maturation & development.
Lymphocytes recognise single specific molecules
What is clonal selection?
Antigen selects & stimulates each cell that expresses a receptor that it can bind to.
How do T cells undergo clonal expansion?
Cytokines stimulates T cell clonal expansion
What happens when B cells undergo clonal expansion?
They produce antibodies
What is education of lymphocytes?
Making sure they can recognise self & non-self antigens
Define tolerance.
Lack of response to self established during lymphocyte maturation
Define central tolerance.
Tolerance that occurs during cell development & education in the bone marrow or thymus
Define peripheral tolerance.
Tolerance that occurs during the immune response to account for cells that escaped central tolerance.
What happens to cells with self-antigen receptors?
If found during central tolerance, they will undergo apoptosis. If found during peripheral tolerance, they will undergo either apoptosis or anergy.
Define auto-immunity.
When tolerance fails & lymphocytes attack cells with self-antigens
