Immunology: Antibodies Flashcards
What are lymphocyte receptors?
Found on T & B cells
Assembling of random assortment of molecules that make receptor
Can recognise almost anything
What is the difference between T cell lymphocyte receptors and B cell lymphocyte receptors?
B cell antibody is not membrane-bound
T cell receptor is membrane bound
What are the three stages of B cells?
- Naive
- Plasma cell
- Memory cell
How are B cells activated?
When met with antigen and cell division happens (clonal expansion) and produce antibodies
Explain clonal selection
Antigen-driven antigen-specific
Proliferation of naive but mature B cells
Explain immunoglobulins
Antibodies
High affinity with antigen
Explain B cell receptor signalling
BCR only extended to few amino acids
Intracellular accessory proteins (Iga and IgB)
How are naive B cells activated?
Signal 1: cross-linking of BCR
Signal 2: co-stimulation
Explain T cell dependent activation
T cell specific for same antigen
Would undergo clonal expansion and activation first to be able to help B cell
Explain B cell activation
Class switching - type of antibody made
Somatic hypermutation - make better antibodies
Career decision - plasma cell and memory
What do antibodies do?
Activate complement, neutralise, opsonisation, ADCC, degranulation
What is neutralising?
Block entry of pathogen
What do Fc receptors do?
Change behaviour and signalling events
What does opsonisation do?
Make phagocytosis better
What does ADCC mean?
Antibody-dependent cell-mediated cytotoxicity
What does degranulation do?
Causes allergies
What are the four classes of antibodies?
IgG
IgE
IgD
IgM
IgA
Explain IgG and IgE
IgG - defence of fetus, across placenta, most abundant
IgE - allergies, mast cells, degranulation
Explain IgD, IgM and IgA
IgD - differentiation to B cells
IgM - pentamer, first Ab produced in immune response
IgA - breast milk, saliva, dimer
