Unit 6; Immune System Flashcards
What are the three major functions of the immune system
protecting the body
removes dead/damaged tissue and cells
tries to recognize and remove abnormal cells
What are examples of microbes
bacteria, viruses, fungi, protozoa
What are examples of parasites
worms, etc.
What are pathologies
diseases of the immune system
What are the 3 main pathologies
- incorrect response
- overactive response
- lack of response
What does incorrect response lead to
autoimmunity
What does overactive response lead to
allergies
What does lack of response lead to
immunodeficiency
Are bacteria intra or extracellular
both!
Are bacteria prokaryotic or eukaryotic
prokaryotic: no organelles, just a cell with a membrane and a cell wall
Do bacteria need to be inside the host to reproduce
no, they can reproduce outside the host
What type of drugs kill bacteria
antibiotics
Are viruses intra or extracellular
intracellular
Are viruses cells?
no, just a nucleic acid with a protein coat (cannot reproduce alone)
What type of drugs kill viruses
antivirals
How do viruses attack
insert themselves into cell and the viral nucleic acid takes over the cells nucleic acid
Why are immune system organs called lymphoid organs
they contain lymphocytes
What is the difference between interstitial fluid and lymph
just different names!
- interstitial fluid when in the tissues
- lymph when in the lymphatic vessels
What are regions outside of the lymphoid organs called
periphery
What are the two classifications of lymphoid organs
primary and secondary
What are primary lymphoid organs
organs where lymphocytes developed
- bone marrow (all blood cells) (B cells mature here)
- thymus (T cells mature here)
What are secondary lymphoid organs
organs where lymphocytes interact and initiate responses
- spleen, lymph nodes, tonsils, and gut-associated lymphoid tissue (GALT)
What is the function of secondary lymphoid organs
filter blood and lymph
What do afferent lymph vessels do
bring lymphocytes from periphery
What do efferent lymph vessels do
keep lymphocytes circulating
What is the pulp inside lymph nodes for
mixing of lymphocytes and other leukocytes
What three things do arteries and veins supply the body with
nutrients, O2, and non-lymphocytic leukocytes
What lymphoid organs are encapsulated
spleen and lymph nodes
What lymphoid organs are not encapsulated, therefore capable of diffusion
tonsils and GALT
What are the 6 main types of leukocytes
- eosinophils
- basophils
- neutrophils
- monocytes
- lymphocytes
- dendritic cells
**remember NLMEB + D
What are the categories that leukocytes can correspond with
granulocytes, phagocytes, cytotoxic cells, and APCs (antigen-presenting cells)
What are granulocytes
have prominent cytoplasmic granules
- eosinophils, basophils, and neutrophils (and mast cells)
What are phagocytes
can engulf and ingest pathogens
- neutrophils, macrophages, and dendritic cells (and monocytes)
What are cytotoxic cells
killer of other cells (even self cells)
- eosinophils, and some lymphocytes (cytotoxic T and natural killer)
What are APCs (antigen-presenting cells)
display fragments of pathogens on cell surface
- some lymphocytes, dendritic cells, and macrophages
What are antigens
substances recognized by an antibody and induces the immune response
What are antibodies
proteins that bind specifically to antigens and target pathogens for destruction
Eosinophils are what classification(s) of cell with what colour staining granules
cytotoxic granulocytes
- bright pink staining granules
What is the lifespan of an eosinophil
6-12 hours
What is the role of eosinophils
defence against parasites and allergens
Where are eosinophils found
digestive tract, lungs, genital tract, and skin
How do eosinophils respond
bind to an antibody-coated parasite and degranulate (spew granule contents) which kills the parasite
Basophils are what classification of cell with what colour staining granules
granulocytes
- dark blue staining granules
Where are basophils found
in blood (rare in numbers), mast cells in tissue
- found in digestive tract, lungs, and skin
What do the granules of basophils contain
histamine, heparin, and cytokines
What are basophils for
allergic response
What classification of cell are neutrophils
phagocytic granulocytes
What is the lifespan of a neutrophil
1-2 days
What is the most abundant leukocyte
neutrophils
What do the granules of neutrophils contain
cytokines that cause fever and inflammatory response
Monocytes are precursor cells of tissue ______________ and are _________ in the blood
macrophages, uncommon in blood
Monocytes move to the __________ to become _________________
move to tissues to become macrophages
What are macrophages
amoeboid cells that function as scavengers by phagocytosing old RBCs and dead neutrophils
What type of immunity do monocytes play a role in
adaptive immunity
- phagocytosed pathogens are digested, and fragments are placed on the cell surface (APCs)
- that’s why macrophages are called big eaters
What type of immunity do lymphocytes contribute to
adaptive immunity
How much of lymphocytes are actually in circulation
5%, the rest are in lymphoid tissues
What are the 3 types of lymphocyte
T cells, B cells, and natural killer cells
What are B cells called when activated
plasma cells
What are dendritic cells
phagocytic antigen-presenting cells (APCs)
What type of cell has long thin processes (like dendrites on neurons)
dendritic cells (think of the similarity in the name)
Where are dendritic cells found
skin and other organs
What is the function of dendritic cells
engulf pathogens and present their markers on the cell surface, then they travel to secondary lymphoid organs to present the antigens to lymphocytes
What is hematopoiesis guided by
cytokines
What type of cell do all specialized cells come from
pluripotent hematopoietic stem cells
Where are B cells produced and matured
produced and matured in bone marrow
Why are B cells called B cells
derived from research in chickens
What is important about B cells
produce antibodies (can be found on the cell surface as receptors or as free antibodies in the plasma)
Where are T cells produced and matured
produced in the bone marrow, matured in the thymus
Why are T cells called T cells
mature in the thymus (T for thymus)
What is important about T cells
use contact-dependant signalling via T-cell receptor on the T-cell membrane
- can only bind to MHC-antigen complexes (not free Ag)
What does MHC stand for
major histocompatibility complex
What are MHCs
proteins expressed on the surface of cells that display “self-antigens” and “non-self antigens”
Who would have identical sets of MHCs
identical twins
What are class one MHCs
found on all nucleated cells
- can display self or non-self antigens
What are class two MHCs
found only on APCs
What type of MHC do APCs have
class one and class two
What happens when an MHC is infected
display antigens on class 1 instead of class 2
What are the 3 subtypes of T cell
cytotoxic, helper, and regulatory
(Tc, Th, Treg)
What are cytotoxic T cells
recognize antigens on class 1 MHCs and kills the cell
What are helper T cells
recognize antigens present on class 2 MHCs and promote differentiation of B cells/T cells (+ activate macrophages)
What are regulatory T cells
recognize antigens on class 2 MHCs and suppress other immune cells to prevent excessive immune responses
What’re the 4 steps when a foreign invader enters
detect and identify the pathogen, communicate with other cells, recruitment of help and coordination of the response, destruction or suppression of the invader
What do cytokines do
affect the growth and activity of other cells
Which type of immunity is more rapid, and less specific
innate
Which type of immunity is slower, but more specific
adaptive
What is a hallmark of innate immunity
inflammation
What are the two categories of adaptive immunity
cell-mediated immunity and antibody-mediated immunity
What is the first line of defence in innate immunity
skin (physical barriers)
What is the second line of defence in innate immunity
patrolling or stationary leukocytes & blood proteins
What is the majority of innate immune system cells
phagocytes
How do phagocytes attract other cells
release cytokines
Chemicals that attract other immune cells are called….
chemotaxis
What type of cells are attracted by chemotaxins
cytokines and other immune blood proteins
products of tissue injury
bacterial products
What is extraversion
when phagocytes leave circulation and enter the tissue through capillary walls
What is opsonization
when blood proteins bind to a pathogen to “tag” it
- happens when a pathogen doesn’t have surface features that a phagocyte can recognize
What is the blood protein that tags pathogens
opsonin
What is a phagosome
name for the vesicle formed when a pathogen is ingested
Once the phagocyte (with ingested pathogen) fuses with a lysosome, it is called…
phagolysosome
What is pus
when dead phagocytes, tissue fluids, and debris collect at the site of injury
What lymphocyte is associated with innate immunity instead of adaptive
natural killer cells
What is the purpose of NK cells
initiate apoptosis in pathogen-infected cells
What important cytokines are produced by NK cells
interferons
What are interferons
interfere with viral replication
IFN a and b induce…
antiviral state in nearby cells (signal to other cells that there is a virus present)
IFN y…
activates macrophages and other immune cells
What does inflammation do to capillaries
increases capillary permeability
What interleukin mediates the inflammatory response
IL-1
What are the functions of IL-1
- act on endothelial cells lining the blood vessels
- act on liver cells to produce blood proteins involving damage control
- induce fever
- stimulate cytokine production
What are complement proteins
cascade of events that occurs in innate immunity by blood proteins
What are complement proteins activated by
sequential proteolysis
What do complement proteins subsequently form
MAC attack (membrane attack complex)
What is the MAC attack
makes holes in the pathogen membrane, which allows ions to enter and lyses the pathogen, killing it
What are other terms for adaptive immunity
acquired or specific immunity
What cells are involved in adaptive immunity
T cells and B cells
All lymphocytes produce:
cytokines
What does it mean to expand clonally
make identical copies of itself and multiply to create an “army”
What is specificity
each cell recognizes a different specific pathogen
What are naïve cells
don’t know things… have never seen its particular antigen (body has never had its particular infection)
Once a pathogen has recognized its pathogen, it is no longer naïve, it is an ______________ cell
effector
What cells produce the antibodies needed in antibody-mediated immunity
B cells
What is an interchangeable term for antibodies
immunoglobulins
Where can antibodies lie
plasma or cell membrane protein of B lymphocytes
When activated, B cells become…
plasma cells
At which response level is there a delayed response period
primary response (on first exposure)
What is IgM
produced during primary response: activates compliment
What is IgA
found in secretions
What is IgD
were not sure what its function is
What is IgG
produced in secondary responses: recognized by mast cells
What is IgE
allergic responses
Where are the antigen binding sites on an antibody
on the fragment antigen binding region (Fab)
What part of the antibody determines which type of immunoglobulin the antibody belongs to
the stem (Fc region)
What is the hinge region on an antibody
between the Fc and the Fab regions on the antibody
Antibodies make up ___% of proteins found in plasma
20%
Do antibodies attack the pathogens themselves
no, they make pathogens more visible to immune cells to be destroyed
What are the 7 antibody functions
- act as opsonins
- caused antigen clumping
- neutralize bacterial toxins
- activate compliment
- activate B cells
- activate antibody-dependant immunity
- activate mast cells to degranulate
Can T cells bind to free antibodies
no, must bind to antigens presented on the MHC receptor
What is the purpose of class 1 MHCs
defend against pathogens inside the cell
What do class 1 MHCs release
perforin and granzymes
What is perforin
formes pores in target cell (think perforate)
What are granzymes
enter through the pores (perforin) and trigger apoptosis
Tc cells can also express the ________ ligand to kill a target cell
Fas (on antibody)
What is the purpose of class 2 MHCs
defend against extracellular pathogens
How do helper T cells respond to class 2 MHCs
secreting cytokines that activate other immune cells
How do regulatory T cells respond to class 2 MHCs
secreting cytokines that suppress other immune cells
What are the 4 different responses of the 2 immunity types
- extracellular
- intracellular
- allergic
- foreign tissue
Bacterial invasion often results in the __________________ response
inflammatory
When complement proteins are activated by bacterial cell wall components, what do they act as
chemotaxins, MAC attack, and opsonins
What occurs in the response to bacterial invasion
- complement proteins activated
- phagocytes produce cytokines and activated cells produce antigens
- cytokines are secreted by B and helper T cells
- B cells clonally expand (becoming plasma cells)
- most cells die at end, but some become memory
Phagocytes and antibodies ___________ & __________ viruses on first exposure
opsonize and neutralize
What occurs in response to viral infection
- infected host cell produces IFNb and macrophages produce IFNa (antiviral state in nearby cells)
- cytokines secreted from host cells and macrophages activate NK and cytotoxic T cells
- T cells recognize viral peptides on class 1 MHCs and kill it
- perforin and granzymes induce apoptosis
For viruses that turn off the class 1 MHC expression, what happens
NK cells kill any cell without class 1 MHCs, therefore it is killed anyway
Allergic responses, or hypersensitivities, happen in what two types
immediate hypersensitivity and delayed-type hypersensitivity
What mediates immediate hypersensitivity
antibodies
What mediates delayed type hypersensitivity
T cells and macrophages
What happens in response to allergens
sensitization phase: equivalent to primary immune response
- antigen ingested by APC, activates helper T cells
- helper T cells activate B cells to make IgE
- helper T cells and B cells become memory cells
re-exposure phase: equivalent to secondary immune response
- IgE on mast cells recognizes allergen
- mast cells degranulate releasing histamine and cytokines, resulting in inflammatory response
What is another term for MHC
human leukocyte antigens (HLA)
How does transplantation work in relation to HLA
if the recipient and the donor have the same HLA type, the transplantation is possible
What are the two negative outcomes of a transplant
rejection of host by the donor tissue: graft vs host
rejection of donor tissue by host: host vs graft
What is a common example of tissue donation
blood transfusion
Do RBCs contain MHCs
no, remember RBCs have no nucleus, and MHCs present on only nucleated cells
If the wrong type of blood is introduced, what happens
blood rejects and agglutinate (clump)
- this is dangerous in the body cause blood clots can lead to a number of health defects
If people express antibodies for blood types that they do NOT have, what would a person with type A blood present
anti-B antibodies
Antibody binding of blood would cause activation of complement, which would lead to…
MAC attack; cells lyse, which would kill blood cells
