Transcript Immune Memory and Vaccines

Immune Memory and Vaccines
• B-cell activation and Memory B-cells
• Acquired Immunity
– “natural” after infection or disease
– “artificial” through vaccine
• Vaccines
When B-cells activate…
B-cell clones
• Of 1011 B-cells in body
(remember that each has a
gene combination for a specific
antibody), most will never
encounter an antigen that their
antibody or BCR “recognize” or
that causes them to activate
• For those who do, they begin
undergoing mitosis, forming
clones or cells that have the
exact same antibody (or BCR)
gene combination
• The clone cells become either:
– Plasma cells that make antibodies
or immunoglobulins that are
released into the blood stream
– Memory B-cells…
Memory B-cells
• Have BCR that
recognizes antigen
that caused original
“mother cell”
activation
• Thousands
(millions?) are made
so body is ready for
next exposure to that
antigen
• Thus, secondary
response (when
body is again
exposed to same
antigen) is much
faster than primary
response
Memory T-cells
• Virtually
same
process
happens with
T-cells
Acquired Immunity
• Presence of Memory B-cells and Memory T-cells
provides acquired immunity to the diseasecausing microbe that originally introduced the
antigens that caused the “mother cells” to
activate.
• Two ways to acquire this kind of active
immunity* (active because the body actively
produces antibodies to trigger a quick secondary
response)
– Naturally acquired active immunity: example—
common cold viruses
– “Artificially” acquired active immunity: Vaccines…
*Passive immunity: Antibodies come from outside source—body does not
produce them from activated B-cells. Source can be “natural (from mother’s
blood across placenta in fetus or mother’s milk during nursing in infant) or
“artificial” as in antibody injections, frequently used against venoms
(“antivenom) or for temporary immune protection (“antiserum” made of
antibodies harvested from cell cultures of cells with antibody that respond to
antigen associated with disease-causing agent)
• Edward Jenner and small pox vaccine (1796)
• Vaccines can come from:
–
–
–
–
Similar disease (cow pox/small pox)
Living, “attenuated” virus (polio)
Dead virus (most vaccines)
Antigens from disease-causing organism—
usually case with bacterial vaccines
What is vaccine?
How do vaccines work?
(and why do they work with some
diseases and not others?)
• Disease-causing organism must
have antigens that immune
system can “see”
• Disease-causing organism must
not mutate too rapidly (AIDS) or
have too many different strains or
causative-agents (common cold)
• “Herd” vaccination is probably
more important than individual
protection
• Flu vaccine example:
Vaccine Development and Production