adaptive immunity - b cell Flashcards
b cells are part of the — immune system as they have —- response
they produce – which is crucial to fight pathogens ( mainly extracellular pathogens)
- adaptive
- antigen specific
- antibodies
-BCR are found in the cell —- receptor or b cells and they recognise antigen in —- form
-anitgen recognition cause b cell – where they — and differentiates into —
each plasma cell product trillions of —-
- the — are the secreted form of the BCR (which is a membrane bound immunoglobulin molecule )
- antibodies are secreted into — and – which triggers effector response
- cell surface antigen receptor
- biological form ( protein carbs lipids polysaccharides )
- b cell activation
- proliferates
- differentiates into plasma cells
- antibodies ( aka immunoglobin aka ig)
- antibodies
- circulation
- mucosal membranes
life cycle of b cells :
1- b cell development occurs in — and its – to antigen exposure:
* BCR rearrangement
* Selection process
* Now known as Naïve B cells
2- b cell activation occurs in — and its — antigen exposure :
* B cell is ACTIVATED
* Differentiation into
plasma cells
3- b cell function occurs in— and its – to recognition antigen
- bone marrow aka primary lymphoid antigen
- prior
- lymph nodes . spleen aka 2ndart lymphoid tissues
- initial
- peripheral tissues where needed
- response to
( check slide 9 )
- A membrane bound IgM is also called the —
- It is composed of— chains and —- chains
and —- chains - They are assembled to form a — structure
- The heavy and light chains are attached via—- bonds
- The — region is the variable ‘antigen-binding site’
- The — region is the constant region
- BCR
- 4 polypeptides
- 2 heavy chains (H) and 2 light chains ( L)
- Y
- disulfied bonds
- v region
- c regions
- At any one time we have millions of B cells in our body, each having a
BCR with a different—- for antigen - How? During B cell development—- of BCR genes (VDJ
recombination) occurs and variable BCRs with unique specificities are
generated! - —–– randomly combine V(D)J genes to form VDJ or VJ
segments →—- different combinations!!!!!
- specifity
- gener rearrangement
- CDJ recombination
- 10 power 11
b cell activation occurs in 2 ways:
1- — > which use antibody class isotope-switched high affinity antibodies , memory b cells , long lived plasma cells
2- —> mainly IgM ,low affinity antibodies , short lived plasma cells
- T cell dependent ( as follicular b cells )
- T cell independent ( as b-1 cells , marginal zone b cell )
b cell activation requires — signals
1- singnal : — binding to BCR
*B cell antigen receptor will recognise—- (protein, carbohydrate, lipid, polysaccharide)
*Triggers—- of antigen
*B cells excellent—- and—-
*If T-independent, the recognition of an antigen is — to activate the B cells to produce— levels of IgM antibodies (no second signal)
*If T-dependent (i.e. protein antigen), peptides are presented on MHC class —
*Up-regulation of CD40 a co-stimulatory receptor
*Up-regulation of cytokine receptors
2d signal:
use — help
* ACTIVATED —- will recognise antigen presented by B cells
* The T cell upregulates costimulatory molecules —- which binds to —on —
* The production of— drive B cell proliferation and differentiation
- 2 signals
- antiges
- antigens
- phagocytosis
- phagocytes and APC
- enough
- low
- class ii
- T cell help
- helper T cells
- CD40L
- CD40
- b cells
- cytokines
- —- are secreted proteins which recognise — on the surface of pathogens using their antigen binding site within the variable regions
*—- can be any biological molecule –protein, carbohydrate, lipid, polysaccharide - The—- region activates different effectors (complement proteins or innate immune cells) that eliminates these microbes and toxins
- The ‘type’ of— region defines the isotype of an antibody
- antibodies
- epitopes
- epitopes
- constant
- constant
( info : The “epitope” is the specific part of the antigen that is
recognised by T and B cell receptors)
b cell function occurs in — where needed and the functions include :
- peripheral tissue
1- neutralisation of microbes n toxins by igG igA
2- opsonisation and phagocytosis of microbes IgG
3- antibodies dependent cellular cytotoxicity IgG (igE)
4- phagocytosis of mcuorbes opsonisation w complement fragment ( c3b) , activation of complement (IgG , igM)
5- inflammation
6- lysis of microbes
antibodies structural features:
1. —–: recognises antigen and binds incredibly tightly – Incredibly specific – can distinguish between very similar epitopes
2. ——:where — protein binds to start the classical complement cascade
3.binding site for —- Macrophages, mast cells,basophils, NK cells, neutrophils and eosinophils all have Fc receptors that will recognise the
Fc portion of an antibody and
bind helps antibody function
- anitgen binding site
- complement biding site
- C1q
- immune cells
( check slide 23 structure sssosooso important )
b cell activation results in :
- antibodies secretion
- isotope switching where only when T cell dependent
- affinity maturation when only T cell dependent
- memory b cell only when T cell dependent
—- anything the immune system recognises as non self
antigen
- — is the first antibody secreted upon infection
- But B cells can isotype switch into making ——- isoforms as required
- During isotype switching the antigen binding site remains —- but the constant region of the heavy chain is —-
- The process of isotype switching is induced by —– interaction and—- released by T helper cells
- Each isotype has a slightly different function as discussed later
- IgM
- igG igA igE igD
- same
- replaced
-CD40-CD40L - cytokines
—- complement activation
—- oponiszation , phagocytpsis , complement activation , neonatal immunity ( placental transfer )
—– immunity against helminths , mast cells degranulation ( immediate hypersensivity )
—- mucosal immunity ) transpot IgA through epithelia )
IgM
IgG ( most skilled ) IGG1 IGG3
IgE , IgG4
- IgA
- —- is the process by which the
affinity of antibodies produced in response to an antigen increases with— or—- exposure - With repeated exposures to the same antigen, a host will produce antibodies of successively—- affinities
- A secondary response can produce antibodies with several fold — affinity than in a primary response
- one way this occurs is by —- in the variable antigen binding region of the antibody
- affinity maturation
- prolonged
- repeated
- great
- great
- random mutation
