Exam 3 Lecture 15: Memory & Vaccination Flashcards
What is immunological memory?
Retention of information from a previous exposure that can be used during a re-encounter with the same antigen
Second response is bigger/greater than first response
What is different between a primary and memory response
Primary:
Slower, weaker, high activation threshold,
IgM first, then isotype switching
low affinity first, then high affinity
few pathogen specific cells
first antigen expsure
Memory:
faster, stronger, low act. threshold
IgG, IgA, IgE from start
high affinity from start
many path. specific cells
2nd and following exposure
What are the 3 main players in a memory response?
Long lived plasma cells
Memory B Cells
Memory CD4 and CD8 cells
How are memory T cells generated?
Asymmetrical division
Naive T cell > divides: 1 effector + 1 memory
What distinguishes memory T cells from naïve or effector T cells?
Never die/lose ability to proliferate
Easier to activate than naive
Continually recirculate
What are the 3 different types of memory T cells and where are they located?
Tcm: central memory
Stay in 2ndary lymphoid tissues, lymph, blood
Tem: effector memory
Circulate through entire body
Trm: resident memory
Stay in tissues they were generated in
How do long-lived plasma cells and memory B cells outcompete other cells?
Inhibitory receptor, FcγRIIB1 in presence of IgG makes it hard for naive B cells to compete with memory B cells
Inhibits activating signals and suppress antigen presentation
How does an antibody memory response lead to potential problems for a second pregnancy due to RhD mismatch?
First pregnancy: RhD+ fetus induces maternal
anti-RhD IgG > (weak) primary immune response > minor destruction of fetal erythrocytes > healthy baby
Second pregnancy: very strong secondary immune response > massive destruction of fetal erythrocytes > anemic baby
Treatment (during first pregnancy): anti-RhD
IgG leads to death of naïve B cells specific for
RhD antigen > no fetal erythrocytes destroyed > all pregnancies lead to healthy babies
What is the “original antigenic sin?”
A response against a newer antigen is suppressed in favor of an older antigen
i.e. in rapidly mutating pathogens, the antigens change over time as new strains develop, leading to eventual strains having completely different antigens than the strain you developed immunity to, leading to a primary immune response again
Can be overcome by repeated exposure (getting flu and covid vaccines every year)
What is variolation?
the practice of introducing smallpox (variola virus) antigens from dried pustules derived from patients with mild disease through intradermal scratches
Who is Edward Jenner?
Grandfather of vaccination
It was known that exposure to cowpox lead to resistance in smallpox
Jenner tested whether this previous exposure was actually providing protection against smallpox
Published “On the origin of vaccine inoculation”
What is the purpose of vaccines?
Expose the immune system to antigens
that will be recognized by the adaptive immune system (T and B cells) to generate memory responses
Components of a vaccine
Antigens ans Adjuvents
What are different types of vaccines?
Live: modified live or attenuated (weakened)
ex. Measles, Mumps
Dead: heat-killed, formalin-fixed etc
ex. Typhus fever
Subunit: product or part of infectious disease agent
(inactivated toxin = toxoid)
ex. Tetanus, Hepatitis
DNA or RNA: genetic material coding for components
of the infectious disease agent
ex.
Recombinant: gene(s) from infectious disease agent
‘recombined’ into a ‘vector’
ex. Hepatitis, Rotovirus
What is an adjuvant and what
are some examples of adjuvants?
The activating agent in a vaccine
Induce an inflammatory response by activating DCs and macrophages to induce co-stimmulation
Retain antigen/vaccine in body
Examples
Mineral oil, aluminum salts, liposomes, TLR agonists
