Chapter 12 Flashcards
cell that is the main regulator in the adaptive immune response
helper T cell
HIV’s preferred host
helper T cell
when pathogens enter a cut…
they go to the nearest lymph node
essence of vaccines
memory cells
vaccines
1) dead form of virus
or
2) DNA or RNA of the virus
cells of the adaptive immune system
helper T cell, memory helper T cells, cytotioxic T cell, active crytotoxic T cells, memory cytotoxic T cells, B cell, plasma cells, memory B cells
tumor
your own cells proliferating
linked to an increase in the expression of pro-inflammatory cytokines
sickness, stress, depression, aging, and other somatic conditions that detrimentally affect cognitive functions
_________ may benefit from anti-inflammatory immune requirement
hippocampus
cytokines principally shown to have a detrimental effect on cognitive function
TDN, IL-1, IL-6, and IL-12
innate immune cells
(both peripheral and CNS resident) were proposed as the source of pro-inflammatory cytokines
chroid plexus
source of most of the CSF; CSF produced in chroid plexus flows within the confines of the meninges
functions of CSF
1) CSF in the subarachnoid space has a “buoyant” function and also a “buffering” zome for a brain located within a rigid skull
2) regulation of the extracellular environment of neurons
CSF drains into cervical lymph nodes
enabling peripheral T cells to respond to CNS antigens under certain pathological conditions
plausible that neuroimmune interactions affecting learning and memory originate in…
the meninges and choroid plexus/ventricular areas rather than in the parenchyma
multiple sclerosis (MS)
- autoimmune demyelinating disease
- affects transmission of neural messages
- the immune system attacks the myelin sheath, thinking that it is a foreign body
- occurs at scattered locations within the central nervous system
- process leaves hard patches of debris called sclerotic plaques
how multiple sclerosis (MS) attacks
- white blood cells attack neurons
- affect fatty tissues (myelin) around the nerve fibers in brain, spinal cord
- nerve signals are slowed or blacked, causes MS symptoms
MS treatment
- interferon beta
- glatiramer acetate (also known as copaxone or copolymer-1)
pregnancy and MS
- higher prevalence of MS in females compared to males and a decrease in disease activity during pregnancy, particularly in the third trimester
- fetus represents an “allograft” since it harbors antigens inherited from the father and the natural immunomodulation is thus important to prevent fetal rejection
- pregnancy is characterized by the presence of potentially neuroprotective hormones including estrogens, progesterone, and prolactin
estrogen and MS treatment
- estriol was administered in a pilot clinical trial to women with MS in an attempt to recapitulate the protective effect of pregnancy on disease
- oral estriol treatment was associated with significant decreases in CD4+ and CD8+ T cells
- reductions of enhancing lesions in brain
encephalitis
when the brain is inflamed caused by herpes simplex virus, rabies, or acute anterior poliomyelitis reaching the brain
rabies
fatal viral disease that causes brain damage and is usually transmitted through bite of infected animal
acute anterior poliomyelitis
viral disease that destroys motor neurons of brain and spinal cord
meningitis
inflammation or swelling of the meninges surrounding the brain and spinal cord caused by viruses or bacteria
transmissible spongiform encephalopathies
- mad cow disease
- bovine spongiform encephalopathy (BSE)
- can be transmitted to humans
- Creutzfeldt-Jakob disease a variant
- prion
- sporadic disease - occurs rarely and is not obviously caused by heredity or infectious agent
- result in progressive degeneration of the brain and eventual death
- PrP^Sc
prions
proteinaceous infectious particle
types of prions
- scrapie in sheep
- bovine spongiform encephalopathy (BSE) or mad cow disease
- Creutzfeldt-Jakob disease (CJD) and variant CJD (vCJD) in humans
- kuru in humans
PrP^Sc
- mad cow disease
- causes PrP^C protein to change its conformation to abnormal form
- newly produced PrP^Sc molecules convert more normal molecules to the abnormal form through unknown mechanism
Alzheimer’s disease (AD)
- degenerative brain disorder of unknown origin
- causes progressive memory loss, motor deficits, and eventual death
- amyloid plaque
- beta-amyloid
- neurofibrillary tangle beta-amyloid precursor protein (APP)
- secretase
detrimental effects of neuroimmune interactions
- autoimmunity
- onset and progression of neurodegenerative disease
- exacerbation of injury-induced loss of neuronal function
general functions of immunity when it works
- defend against infection by viruses, bacteria, fungi, parasites, etc.
- destroy and recycle worn-out cells
- identify and destroy abnormal (cancer) cells
general functions of immunity when it doesn’t work
- allergies
- autoimmune diseases
- limits tissue/organ transplants
types of immunity
- innate
- acquired
innate immunity
- non-specific
- inherited
- rapid
- no memory
acquired immunity
- specific
- adaptive
- slower
- memory
pathogens
agents that cause disease
response in immune system
- dedicated cells of the immune system interact with and destroy pathogens
- first lines of defense help prevent pathogens from gaining entry to the body (e.g., skin, mucus, hair)
- second and third lines of defense: innate and adaptive immunity
recognition in immune system
molecular recognition allows detection of non-self molecules, particles, and cells
who has innate immunity
all animals and plants
- defense active immediately upon infection
- includes barrier defenses
who has adaptive immunity
vertebrates
- activated after the innate response and develops more slowly
overview of innate immunity
- recognition of traits shared by broad ranges of pathogens, using a small set of receptors
- rapid response
- barrier defenses: skin, mucous membranes, secretions
- internal defenses: phagocytic cells, natural killer cells, antimicrobial proteins, inflammatory response
barrier defenses
include the skin and mucous membranes of the respiratory, urinary, and reproductive tracts
- mucus traps and allows for the removal of microbes
- lysozymes in saliva, mucus, and tears can destroy bacteria
- the low pH of skin and the digestive system prevents growth of many bacteria
overview of adaptive immunity
- recognition of traits specific to particular pathogens, using a vast array of receptors
- slower response
- humoral response: antibodies defend against infection in body fluids
- cell-mediated response: cytotoxic cells defend against infection in body cells
cells of the immune system
white blood cells
- less than 1% contained in blood
- rest contained in tissues of the immune system
lymph
a colorless fluid containing white blood cells that drains through the lymphatic system into the bloodstream
tissues of the immune system
- tonsils
- lymph nodes
- thymus
- spleen
- bone marrow
- lymphatic vessels
- lymphocyte accumulation in small intestine
bone marrow
site of B-cell development
VAN
vein, artery, nerve
- any time there is a nerve, it is connected to a vein and an artery
leukocytes
- white blood cells
- all arise from pluripotent stem cells
pluripotent stem cells
in bone marrow; give rise to T cells and B cells (lymphocytes)
- B cells mature inside bone marrow
- T cells migrate to thymus to mature
- once mature, both move to peripheral lymphoid organs (lymph nodes, spleen) where they carry out their effects
three types of phagocytic cells in mammals
neutrophils, macrophages, dendritic cells
neutrophils
circulate in the blood; go up in numbers to indicate onset of infection
macrophages
often reside permanently in organs and tissues
- stays
type of white blood cell that surrounds and kills microorganisms, remove dead cells, and stimulates actions of other immune system cells
dendritic cells
stimulate development of adaptive immunity (relative of macrophages)
- moves
- migrate to lymph nodes after interacting with pathogens; there they activate other immune cells
brief summary of phagocytic cells and immunity
1) pseudopodia surround pathogens
2) pathogens are engulfed by endocytosis
3) vacuole forms
4) vacuole and lysosome fuse
5) pathogens destroyed
6) debris from pathogens released
antigen presentation
- important process because it allows wandering lymphocytes to become activated
- links nonspecific and specific immune responses
- passing of microbial fragments from the phagolysosome to the endoplasmic reticulum initiates antigen presentation
- macrophages and dendritic cells become antigen-presenting cells (APC)
pain and swelling
brought about by molecules released upon injury or infection
1) histamines and cytokines released; capillaries dilate
2) antimicrobial peptides enter tissue; neutrophils are recruited
3) neutrophils digest pathogens and cell debris; tissue heals
histamines
causes arteries to open up a little bit to allow neutrophil movement
two types of responses in the immune system
- innate
- adaptive
innate immune system response
cells have pattern recognition receptors— detect patterns of pathogen-associated molecules not on host cells
adaptive immune system response
cells such as phagocytic macrophages stimulate adaptive immune response by other cells
one way innate system helps activate adaptive system
- dendritic cells (or also macrophages) phagocytose invading bacteria; cells then put microbial antigens on surface of cell and migrate to lymphatic vessel
- there they present antigen to T cell; co-stimulatory protein also presented to T cells; activated T cells (cytotoxic T cells) then migrate back to site of infection to kill invading cells or help macrophages do this
- other activated T cells (helper T cells) stay in lymphoid tissue and help B cells to produce antibodies that are circulated through the body and coat microbe to allow phagocytosis; also activate cytotoxic T cells and macrophages
two places where pathogens can reside
inside a cell or in the fluid outside of the cell
cytotoxic T cell
goes to kill pathogens when they are living inside of the cell
- clears pathogens in infected cells
B cell
turns into a plasma cell that makes antibodies
- clears pathogens in fluid
antibodies
coat pathogens when they are in the fluid
how lymphocytes learn to recognize foreign antigens but not self-antigens in central lymphoid organ
- during maturation of lymphocytes in central lymphoid organ immature cells express wide variety of antigen receptors on their surface
- they are also exposed during this time to self-antigens
- if receptor that cell makes recognizes self-antigen, the receptor can: be modified (receptor editing) so that it no longer recognizes self; undergo apoptosis and die
- if cells have their receptors edited or produce receptors that are not self-recognizing, the mature lymphocyte is released into circulation so that it can go to a peripheral lymphoid organ
- some lymphocytes escape from central organ even with self-recognizing receptor
how lymphocytes learn to recognize foreign antigens but not self-antigens in peripheral lymphoid organ
- mature naïve lymphocytes gather
- they can undergo responses to antigens from a foreign source to produce effector and memory cells
- the escaped lymphocyte recognizes self antigen in peripheral organ and undergoes either clonal deletion or clonal inactivation or clonal suppression all of which disable the self-recognizing lymphocyte
