BIO 343 Lecture Notes - Lecture 11: Macrophage, Fetus, 18 Months
Immunology Chapter 11: Immunological Memory and Vaccination
Hayden Casassa
• In a secondary immune response, the infection is often cleared with few or no symptoms
• A suessful pia espose ahiees to goals…
o Effector cells + molecules clear infection and it temporarily strengthens immune responses to
prevent reinfection
▪ If this does’t ou, patiet eithe dies o suffes fo hoi disease
o It establishes a state of long-term immunological memory
▪ Expanded clones of memory B cells
▪ Expanded clones of memory T cells
• Following primary infection, plasma cells that live a few months secrete specific Abs to prevent
reinfection from strain with this term called protective immunity
o Protective immunity is generally only against seasonal strains since most plasma cells die within
a year and effector T cells within a few weeks
• Advantages of B memory cells in secondary response vs naïve B cells (Discussion Question)
o Memory cells specific for a pathogen are more abundant than naïve B cells
▪ Wh ae eo ells ette… eause thee ae oe of the due to loal epasio
o Memory cells are more sensitive to lower amounts of pathogen and are more easily activated
▪ The’e oe easil atiated due to highe affiit BCR due to affiit atuatio
▪ They also have higher levels Class 2 MHC and B7
• This is what helps present to make antibodies
• Therefore, then can then help activate TFH cells better
o Memory B cells have undergone isotype switching
▪ Switches away from IgM to a better BCR
o Memory B cells have undergone affinity maturation
▪ Therefore, they make better antibodies
• Components of immunological memory: Memory B and T cells
o In beginning of primary response, mostly effector T cells and B cells are made
o Later, long-lived pathogen specific CD8 and specific CD4 cells and B cells are made
o Upon subsequent exposure to same pathogen, the secondary response is stronger and faster
• Comparison of Primary vs Secondary Humoral (Ab) response to the same pathogen.. The Secondary
espose is…
o Higher amount of Ab produced
o Ab is produced faster (no lag)
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o Ab levels remain higher for longer period of time
o Different Ab isotypes produced
o Higher affinity abs are produced
• Memory cells get even better and better with every subsequent exposure which is why we get boosters
• Memory T cells
o Less is known about memory t cells vs memory b cells
o Unlike effector T cells, memory T cells are long-lived
o Do’t euie o-stimulation via CD28 similar to effector T cells to allow fast secondary
response
o Memory T cells can recirculate through peripheral tissue and be activated at site of the
infection
• Goal of vaccination is to immunize individuals with a benign form of a pathogen and induce
immunological memory
o In vaccinated individual, the infection is met with a secondary immune response
o Some vaccines induce immunological memory for life while others need boosters
• Small Pox makes a protein that blocks all types of IFN production
o Half the US has’t ee aiated
o Live vaccina virus was used as vaccine to eradicate smallpox
▪ Virus is hybrid between variola (smallpox) and cowpox
• It is primarily specific-memory B cells that participate in the secondary immune response
o Activation of specific naïve B cells is suppressed
o Specific naïve B cells are suppressed to ensure that low affinity Abs and IgM are not made in
secondary response
▪ This would be bad because you would go down in quality of abs
o Mechanism: Specific IgG generated against previous infection can inhibit the activation of naïve
B cells specific for the same pathogen
• Immune Complexes, comprised of the pathogen, and previously made IgG, suppress naïve B cell
activation by simultaneously cross-linking the BCR and FcyRIIB1
o Memory B cells do not express FcyRIIB1 and so the Ag-Ab binding to the BCR sends a positive
signal to activate the memory B cell
• Inhibition of naïve B cells by immune complexes is put to practical use in preventing Hemolytic Disease
of the Newborn
• Rhesus D antigen
o Highly polymorphic RBC antigen expressed by majority of population
o One is either positive or negative for antigen
o Tasfusio of RhD+ RBC’s into negative individual will cause production of anti-RhD
• This disease can be cused by Rh+ father and Rh- mother producing fetus with RhD+ fetus
• Mothe’s aïe B ells geeate plasa ells akig ati-RhD IgM Abs
o Fetus is’t at isk sie IgM at oss fetus
find more resources at oneclass.com
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Document Summary
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