Adaptive immune system Flashcards
B cells
originate in bone marrow, are APC, possess B cell antigen binding receptor, produce antibodies.
what’s so special about the adaptive immune system?
Memory, diversity ( broad coverage), specificity ( recognize very small differences between antigens), learning ( self vs foreign)
B cell activation
classical pathway. Antigen binds BCR, rapid B cell division and proliferation. antibody produced by PLASMA CELLS
B cells steps
- differentiation- BCR against specific antigen
- antigen recognition- in peripheral lymph tissues ( spleen and nodes)
- clonal expansion- all cells produced are same as original B cells
- B cell differentiation- divides into Antigen produced plasma cell OR long-lived memory cells
Antibody structure
Fab- antigen binding sites
Fc- recognized by other immune system components
IgM
produced during exposure to antigen, pentameric
IgG
most abundant, cross placenta, long-lived, complement activation, opsonizing antibody: binds to Fc receptor on phagocytes
IgA
mucus, tears, saliva, breastmilk, newborn protection
IgE
allergic reactions, low serum concentration, binds Fc receptor on mast cells
IgD
unknown function, bind on mature B cells
serum vs. plasma
serum- liquid fraction of whole blood after blood is allowed to clot
plasma- liquid fraction of blood when whole blood is collected and treatment with anticoagulant, blood not allowed to clot
MHC I
found on all self-nucleated cells, presents ENDOgenous petides, activates CD8 cytotoxic T cells
MHC II
found only on APCs, presents exogenous peptides, activates CD4 helper T cells
who are professional APC?
dendrites, macrophages, B cells
cell death differences
necrosis- whole cell destroyed at once, cellular debris contaminates the extracellular env and leads to inflammation
apoptosis- programmed cell death, clean contained way to kill cells, prevents inflammation
