adaptive sensing Flashcards
What are features of adaptive immunity
-recognise majority of any microbial or non-microbial molecule (antigens) w/ high degree of specificity
-large receptor diversity
-adaptable; receptors created by somatic recombination of gene segments
What is an antigen
A molecule recognised by adaptive immune cells
what will an antigen bind to
to either a T cell receptor or antibody (B cell receptor), or both
what is an epitope
precise part of antigen recognized by T or B cell receptor - antigen can have multiple epitopes
what is a paratope
the part of the antibody or T cell receptor that binds to the epitope
how do T cells recognise Ag (antigen) presented to them
by professional antigen presenting cells (APC) e.g macrophage
how do B cells recognize Ag (antigen)
on their own
what are 2 features of the T cell antigen receptor
-only membrane bound
-called: T Cell receptor (TCR)
what are 4 features of B cell antigen receptors
-membrane bound and secreted
-secreted form has immune effector functions
-secreted form called antibody (Ab) or immunoglobin (Ig)
-membrane form called B cell receptor (BCR) or surface immunoglobin (slg)
what do surface receptors allow a cell to do
to recognize antigens
how many Ag binding sites does a T cell receptor and antibody have each
T cell receptor - 1 Ag binding site
antibody - 2 Ag binding site
what are the two chains that a T cell receptor is composed of
alpha and beta chain
how are antigen receptors created
somatic recombination
what is VDJ recombinase used for
to recombine different gene segments
what is the role of RSSs (recombination signal sequences)
used to align V, D and J segments
what are steps to create junctional diversity
1)joining of V,D and J (RSSs)
2)addition of bases
3)deletion of bases
4)sequence aligns
5)fill in the gaps
what does the somatic recombination of V, D and J genes allow the creation of
T cell receptors and antibodies (B Cell receptors) that can recognize almost any protein or organic molecule
what is the process of clonal expansion
-T/B cell sees its Ag = becomes activated
-activated T/B cells divide
-all daughter cells have identical Ag specificity
-time to activate + expand Ag-specific T/B cells to effective number = slow adaptive response
what are the advantages of adaptive sensing
-adaptable
-somatic rearrangement of gene segments allows creation of receptors that can recognize almost any antigen
-highly specific
what are the disadvantages of adaptive sensing
-slow, requires time to activate and clonally expand cells w/ receptor
-high specificity = easy for microbe to evade recognition by changing antigen structure
-receptors cant distinguish pathogens from self/innocuous molecules
