Lecture 20 Unit 3 Flashcards
what does antibody mediated immunity rely on?
-the TCRs of Th cells and BCRs on B cells
What does antibody mediated immunity defend the body against
pathogens that live outside of our cells
what does antibody mediated immunity only recognize?
foreign antigens thats presented by MHC II proteins
what is the role of BCRs of B cells?
they are required for antigen binding, endocytosis, processing and presentation via MHC II proteins
what is the role of TCRs in Th cells
they are required for recognition of foreign antigen
how does each new B cell possess a unique pair of genes for its BCR
through genetic recombination
what do BCRs contain?
two copies of a unique variable region
what do the unique variable regions in BCRs do?
they can potentially bind to specific unprocessed foreign antigen
what happens when BCRs don’t bind to an unprocessed self antigen
BCRs become tolerant of our own proteins, nucleic acids, lipids and polysaccharides
through what cell does antigen presentation occur?
a B cell
through what cell does antigen recognition occur?
a Th cell
through what cell does activation occur?
a B cell through costimulation by a Th cell
through what cell does proliferation and differentiation occcur
a B cell
through what cell does action occur?
antibodies produced by plasma cells
what do BCRs do in antigen presentation?
naive B cells bind to free antigen in lymph or interstitial fluid and process it for presentation
how is the free antigen Brough to the cell in antigen presentation?
via endocytosis , it is processed then presented via MHC II
What happens in antigen recognition?
a Th cell interacts with MHC II antigen complex and if binding is tight Th cell secretes cytokines in order to activate the B cell
what happens in activation
activated B cells proliferate into a clone and differentiate into plasma cells and memory B cells
What happens in proliferation and differentiation?
- plasma cells secrete antibodies with the exact same antigen specificity as the original B cell
- memory B cells are produced
What happens in action with effector B cells?
they do not leave the lymphatic system but the antibodies they produce do leave and circulate
where do antibodies travel?
throughout the body extracellular fluids where they will attach to the same antigen that triggered their production
what do antibodies do to antigens?
inactivate it and tag it for desctruction
what are defensive mechanisms used by antibodies?
- neutralization
- immobilization
- agglutination
- precipitation
- complement fixation
- enhancement of phagocytosis
what happens in neutralization?
antigen blocks effects of toxins or prevents its attachment to body cells
