L5 - A Kelly - Adaptive immune system Flashcards
give some examples of where an immune response isnot beneficial
Allergens: pollen, hair, dust mites
Autoimmune diseases: against self tissue
how are autoimmune diseases normally prevented
aquirance of tolerance against self tissues
describe the inate immune system
The innate immune system carries no memory of an encounter with a foreign antigen but it
recognises the nature of the pathogen and helps drive an appropriate adaptive immune response.
describe briefly adaptive immunity
based upon the generation of millions of different recognition molecules or receptors made by clonally variable B and T lymphocytes.
Selection and expansion of cells expressing these receptors takes time but pathogens are recognised with exquisite specificity and the system acquires long-lived memory of the encounter.
why must the adaptive imune repsonse be appropriate for the pathogen?
because different pathogens lead different lifestyles - extra / intracellularly / different compartments
describe the B cell receptor
surface receptor on B lymphocytes
capable of interacting with a wide range of structures such as simple chemicals, sugars, small peptides or large protein complexes such as viruses.
can the BCR recognise stuff in its natural state?
yep
B lymphocytes are generated in the ______ ______ where the genes encoding the BCR…..
B lymphocytes are generated in the bone marrow where the genes encoding the BCR rearrange to produce millions of clones with diverse specificity
Upon activation, B lymphocytes do what?
Upon activation these clones can differentiate into plasma cells which secrete antibody or immunoglobulin.
antibodies are a soluble version of what?
BCR
BCr image
D: antigen
anything that can bind antibody
Antibodies normally interact with …..
Antibodies normally interact with relatively small parts of molecules termed antigenic determinants or epitopes
what are linear epitopes?
Some antibodies may recognise consecutive amino acids within a protein or peptide and these are referred to as linear epitopes
purpose of the constant region of the antibody?
constant region that recruits effector function.
The constant region can be recognised by receptors on cells such as dendritic cells, macrophages, neutrophils, basophils and mast cells and can interact with complement.
picture for primary and secondary response curves
3 ways antibodies work
Neutrilisation
Opsonisation
complement activation
describe how antibodies work : neutrilisation
Blocking the biological activity of a target molecule e.g. a toxin to its receptor.
Describe how antibodies work - opsonisation
antigen + antibody inteacts with Fc receptors on various cells (inc neutrophils and macrophages) allowing them to phagocytose the marked cell
essentailly they promote opsonisation
antibody is an opsonin
describe how antibodies activate complement
Complement is recruited to antibody coated antigen and may cause direct lysis. Complement also functions as an opsonin to enhance phagocytosis.
T lymphocytes arise in the….
T lymphocytes arise in the bone marrow but mature in the thymus.
describe how many clones of T cells with different receptor specificity are generated? - briefly
the genes encoding the T cell receptor (TCR) rearrange to generate clones of T cells with different receptor specificity
(in thymus)