aging of the immune system Flashcards
what is our adaptive immunity?
it takes time to generate an adaptive response
-there is memory in this branch of immunity
-e.g. Polio or chicken Pox, years later your body will still recognize it
adaptive immunity
self-non-self, lag phase, diversity, memory
self/ non-self discrimination: is the present, reaction against foreign
lag phase: present, response takes at least a few days
specificity: limited, the same response is mounted to a wide variety of agents
diversity: extensive, and resulting in a wide
memory: present, subsequent exposures to the same agent induce amplified responses
what is our innate immunity?
natural, encoded in our germ line, present at birth
there is no memory for the innate branch, your body’s response would be the same when you are age 8 or age 12 years old
innate immunity
self-non-self, lag phase, diversity, memory
self- non-self discrimination: the present, reaction is against foreign
lag phase: absent, response is immediate
specificity: limited, the same response is mounted to a wide variety of agents
diversity: limited, hence limited specificity
memory: absent, subsequent exposures to the agent generate the same response
what is an interferon?
response primarily to viruses
what do B cells respond to?
they respond to extracellular things like fungi for example
evidence of immune aging
elderly humans
-increased susceptibility to pathogens
-decreased response to vaccination
what is the thymus?
the thymus is an organ responsible for maturation of immune cells that help to protect the body from against foreign antigens
thymic involution
decreased thymic output
adiposity in thymus
decreased thymic epithelial cells
iL-7 production
Overall changes in older age
decreased telomerase activity
increased tumor incidence
increased infection susceptibility
increased autoimmune/inflammatory reactions
decreased response to vaccination
inflamm-aging
increased inflammatory mediators
increased IL-6, C reactive protein
increased tissue dysfunction
B lymphocytes
decreased naive B cell pool
increased memory B cell
decreased IgM, IgD serum levels
increased IgG, IgA serum levels
T lymphocytes
decreased naive T cell pool
increased memory T cell
decreased TCR diversity
increased CD8 and decreased CD4
what is the prevalence of infectious disease?
- infectious disease risk elevated in elderly
-severe impact on quality of life
-in the USA: pneumonia, influenza, septicemia- are among the top 10 leading causes of death
why are the elderly more susceptible to covid-19?
after covid-19 disease was gone, people had prolonged inflammation release which causes damage in other places, lung damage and this contributed to why people died from disease even after it was gone
in an aged system, there is immunosenescence, inflammaging, viral antagonism, ARDS, cytokine storm, coagulopathy
what is a cytokine storm
is an uncontrolled inflammatory release
covid and the immune system
-recruitment of immune cells to infected sites
-widespread inflammation in lung, kidney, heart, liver, brain
-even with decreases in viral load
-can develop a cytokine release syndrome
how is covid-19 controlled?
to suppress and eliminate the virus:
-recognition
-alert-activation of the immune system
-destroy the virus
-clear the virus
the recognition, alert/activation of immune system, destroying the virus, and clearing the virus are all changed in older adults
clearing of the virus also includes reducing inflammation safely
vaccine efficiency
all the changes contribute to a lower vaccine response for older people
exhausted T cells
overstimulated T cells, activated for prolonged time, tire out (become exhausted)
Naive T cell
diverse when young, but this lessens with age
antigen presentation
crosstalk between innate and adaptive immunity, reduced immune response between T and B cells
proinflammatory monocytes
macrophages are still in the blood in the aged immune response
decreased response to vaccination?
flu vaccine
-65-80% prevention for young adults
-30-50% in aged people( quite a substantial reduction)
-decreased B-cell production
e.g. influenza kills many older people
new vaccines
-decreased efficacy in older adults
-smaller T cell population
