Immunity Flashcards
Cells of the immune system:
- neutrophils
- basophils
- eosinophils
- monocytes
- lymphocytes
Neutrophils are…
phagocytes
Eosinophils destroy…
parasites
Basophils release…
- histamines
- leukotrienes
- prostaglandins
Monocytes are…
macrophages/phagocytes
Types of lymphocytes:
- B lymphocyte
- T lymphocyte
Why would there be an abundance of neutrophils?
bacterial infection
Why would there be an abundance of lymphocytes?
viral infection
Why would there be an abundance of eosinophils?
allergic response
Immune system provides…
resistance to disease
Immune system is made up of two intrinsic systems. What are they?
- innate (nonspecific)
- adaptive (specific)
Innate system are part of which lines of defense?
first and second lines of defense
First line of defense for innate system are…
external body membranes (physical barriers)
- skin
- mucosae
Second line of defense for innate system are…
- antimicrobial proteins
- phagocytes
- inhibit spread of invaders
- inflammation is most important
Adaptive system:
3rd line of defense
- attack specific foreign substances
What are the two categories of lymphoid categories?
- primary: sites where stem cells divide and develop
- secondary: sites where most immune responses occur
What are lymphoid organs?
places where immune cells hang out
Examples of primary lymphoid organs:
- bone marrow
- thymus
Function of bone marrow:
produces mature B cells and immature T cells
Thymus is a primary lymphoid organ because…
- where T cells mature
- has T cells, scattered dendritic cells, epithelial cells, and macrophages
Thymus:
- located above heart
- atrophies after maturity
Examples of secondary lymphoid organs:
- lymph nodes
- spleen
- lymphoid nodules
Function of lymph nodes:
- filter microbes
- macrophages and lymphocytes destroy filtered microbes
Where are lymph nodes located?
scattered throughout lymphatic vessels of body
Function of spleen:
removes microbes and aged/defective erythrocytes
The spleen is the largest…
lymphoid organ
Examples of lymphoid nodules:
- tonsils
- peyer’s patches
- appendix
Innate immunity is the ability of the body to defend itself against…
microbes and other foreign substances without specific recognition of invading pathogens
Innate immunity: function of skin in 1st line defense
- water resistant
- prevents entry of foreign substances
Innate immunity: examples of other physical barriers than skin for 1st line of defense
- mucus
- hair
- cilia
- sebum
- lysozyme
- gastric juice
- vaginal secretions
2nd line of defense for innate immunity comes into play when…
first line is not effective
Innate immunity (2nd line): function of antimicrobial substances
discourage microbial growth via interferons, complement, iron-binding proteins, or antimicrobial proteins
- attack microorganisms directly or hinder its ability to reproduce
Innate immunity (2nd line): function of natural killer cells
release chemicals that lead to death of infected or abnormal body cells
Innate immunity (2nd line): function of phagocytes
- neutrophils and macrophages non-specifically engulf microbial invaders
Innate immunity (2nd line): steps of phagocytosis
- adherence: recognition and attachment
- ingestion
- digestion via fusion w/ lysosome
- killing and degradation via O2 radicals
Innate immunity (2nd line): inflammatory response
- nonspecific response to tissue damage
- rids body of organisms that caused tissue damage and damaged tissues
- promotes wound healing
Causes of inflammation:
- trauma
- chemical agents
- thermal extremes
- pathogenic organisms
What is the most abundant phagocyte?
neutrophils
Neutrophils are aided by…
opsonization: antibodies/complement proteins as opsonin that coat pathogens and make them easier to phagocytose
Macrophages develop from…
monocytes and are the chief phagocytic cells
Free macrophages:
wander through tissue spaces
- ex: alveolar macrophages
Fixed macrophages:
permanent residents of some organs
- ex: stellate macrophages (liver) or microglia (brain)
Helper T cells trigger macrophage to…
produce respiratory burst, which kills pathogens resistant to lysosomal enzymes by releasing free radicals, producing oxidizing chemicals, and increasing pH and osmolarity of phagolysosome
Symptoms and signs of inflammation:
- fever (pyrogenesis)
- redness (rubor)
- swelling (turgor)
- pain (dolor)
- tissue/organ dysfunction (functio laesa)
Sequence of inflammatory events:
- trauma or pathogen leads to acute inflammatory response
- platelet adhesion and vasoconstriction of efferent vessels
- cytokine induced afferent vascular dilation
- activation of complement, clotting, fibrinolysis, kinin system, leukocyte adhesion cascade
- endothelial gaps
Cytokine induced afferent vascular dilation leads to…
increased blood flow to infected/damaged area
Endothelial gaps increase…
vascular permeability and allow extravasation of serum proteins and leukocytes
Natural killer cells are…
- nonphagocytic
- large granular lymphocytes
- part of 1st line of defense
Function of natural killer cells:
- police blood and lymph
- kill cancer and virus-infected cells before adaptive immunity is activated
- attack cells that lack “self” receptors
- secrete potent chemicals that enhance inflammatory response
Natural killer cells kill by inducing…
apoptosis in cancer cells and virus-infected cells
Benefits of inflammation:
- prevents spread of damaging agents
- disposes of cell debris and pathogens
- alerts adaptive immunity
- sets stage for repair
During inflammatory chemical releases, macrophages have…
special pattern recognition receptors called toll-like receptors (TLRs), which trigger release of cytokines that promote inflammation
Kinins, prostaglandins (PGs), and complement:
- causes vasodilation of local arterioles
- make capillaries leaky
- attract leukocytes to area
- trigger pain receptors
- prompting release of more inflammatory chemicals
Vasodilation and increased vascular permeability leads to…
- hyperemia
- redness
- heat
Benefits of edema:
- sweeps foreign material into lymphatic vessels for processing in lymph nodes
- delivers clotting proteins and complement to area
Basics of acute inflammation:
- vasodilation
- increased flow to damaged area
- repair
Acute inflammation: effects of vasodilation
- increased vascular permeability and edema
- allows more blood flow to site
- causes loss of plasma proteins
- permeability changes caused by histamine and kinins
Acute inflammation: increased flow to area increases…
emigration: WBC population goes to damaged site to deal with what is causing response
Acute inflammation: increased flow to area occurs via…
chemotaxis: chemically stimulated movement of phagocytes
- chemoattractants: chemicals that attract phagocytes
Acute inflammation: phagocytes move across capillary wall via…
diapedesis
Acute inflammation: repair occurs once infection has…
been contained or cleared
- can leave scar tissue (collagen fibers more densely arranged)
Clinical presentations of infection:
- pus
- abscess
- tumorlike growth
Pus looks like…
creamy yellow mixture of dead neutrophils, tissue/cells, and living/dead pathogens
Abscess are…
collagen fibers that are laid down, which walls off sac of pus
- might need to be surgically drained
Tumorlike growth (granulomas) occurs b/c of…
bacteria’s ability to resist to digestion by macrophages and stay alive
Most important antimicrobial proteins are…
- interferons
- complement proteins
Interferons are cells that are…
infected with viruses and can secrete IFNs that warn healthy neighboring cells
Chemical cascade includes…
eicosanoids, such as prostaglandins and leukotrienes
What is a complement system?
group of 20 blood proteins that circulate blood in inactive form
Complements are present in…
- plasma
- on cell surfaces
Complements interact w/…
each other to produce biologically active inflammatory mediators
The complement cascade leads to…
- chemotaxis (C5a)
- inflammation (C3a)
- increased capillary permeability (C5a)
- opsonization (C3b)
- cytolysis
Complement cascade is a series of…
enzymatic reactions
Opsonization is the…
promotion of phagocytosis
What are the three pathways to activate phagocytes?
- classical
- lethal binding
- alternate
Describe the classical pathway of activation for phagocytes:
most specific
- antibody dependent activation
- binds C1
Describe the lethal binding pathway of activation for phagocytes:
some specificity
- mannose binding protein
- binds C4
Describe the alternate pathway of activation for phagocytes:
most primitive
- nonspecific
- auto-activation of C3
T/F: nitric oxide from blood vessels and macrophages don’t contribute to inflammation
F, they do contribute
When tissue is destroyed or invaded by leukocytes in inflammation for pain, what happens?
mediators are delivered by circulation and/or released
Examples of proalgesic mediators:
- proinflammatory cytokines
- chemokines
- protons
- nerve growth factor
- prostaglandins
Proalgesic mediators are produced by…
invading leukocytes or by resident cells
Proalgesic mediators can produce…
- analgesic mediators, which counteract pain
- anti-inflammatory cytokines
- opioid peptides
Role of NSAIDs and aspirin in inflammation:
- prevent cyclooxygenase from making prostaglandins
- reduce inflammation
T/F: cytokines are produced in inflammatory response
T, because they promote inflammation
Fever is a systemic response to…
invading microorganisms
What are the benefits for a fever?
- intensifies interferon effect
- inhibits growth of some microbes
- speeds up body repair processes
- liver and spleen to sequester iron and zinc, which are needed by microorganisms
Which molecules are involved in a fever?
- leukocytes
- macrophages
What activates the leukocytes and macrophages during a fever?
foreign substances
When leukocytes and macrophages are exposed to foreign substances, they secrete…
pyrogens, which reset thermostat in hypothalamus
Adaptive immunity develops..
after exposure to antigen
- allows macrophages to show lymphocytes what to look for
Adaptive immunity is regulated by…
release of lymphokines and interleukins
Lymphocytes are activated by…
acquiring disease or by vaccination
Adaptive immunity amplifies _____ and activates _____
inflammatory response, complement
Disadvantage of adaptive immunity:
has to be primed by initial exposure to specific foreign substance, which takes time
T/F: adaptive immunity doesn’t have memory
F, it does for previously encountered antigens
What are the important components of adaptive immunity?
- B and T cells, which are both lymphocytes
- antigen presenting cells (APCs), which don’t respond to specific antigens and play essential auxiliary roles in immunity
B and T cells both must…
- gain immunocompetence
- develop antigen receptors
B cells produce…
antibodies
Types of T cells:
- cytotoxic T cells (CD8)
- helper T cells (CD4)
Humoral immunity is…
antibody mediated adaptive immunity
What is the immune component in humoral immunity?
- antibodies (gamma globulins) that travel in plasma
Antibodies are made by ____ and mature in ____
B-lymphocytes, bone marrow
What is the activated form of B cells?
- plasma cells
- synthesize and secrete antibodies
What is the immune component of cell-mediated immunity?
T-lymphocytes
T-lymphocytes mature in the…
thymus gland
Two types of T-lymphocytes in cell-mediated immunity:
- T8 lymphocytes (comes from CD8), which attack directly
- T4 lymphocytes (comes from CD4), which releases lymphokines that attract granulocytes to area and stimulates mitosis of immune cells
What is the function of memory cells?
remember specific antigens and quickly generate immune response when exposed to same antigen
Cell-mediated immunity gives…
long term protection against some viruses, bacteria, and cancer cells
Cell-mediated immunity involves the use of…
cytotoxic T cells, which attack infected body cells, cancer cells, foreign cells
Two important characteristics of antigens:
- reactivity: antibody binds specifically to the antigen that provoked it
- immunogenicity: ability to provoke an immune response by stimulating production of antibodies
Antigen can be…
- whole or part of cell
- non-microbial
Example of non-microbial antigens:
- egg whites
- pollen
- incompatible blood cells
- transplanted tissues
What is an epitope?
small parts of the antigen where antibodies attach and provokes a response
Antibodies bind…
temporarily to target cell, which inactivates it and marks it for destruction
What are self antigens?
your own antigens, which allows the body to recognize which cells are yours
MHC proteins are important…
self-proteins that are a group of glycoproteins
MHC proteins are coded by…
genes of major histocompatibility complex (MHC), which are specific to each individual
T/F: identical twins have identical MHC
T
MHC proteins have a groove that can hold…
pieces of self or foreign antigen
T-lymphocytes can recognize only…
antigens that are presented on MHC proteins
What is important in tissue/organ transplant rejection?
self-antigens
Two types of antigen presentation:
- exogenous
- endogenous
Steps of exogenous antigen presentation:
- ingest antigen
- digest antigen into peptide fragments
- synthesize MHC-II molecules
- package MHC-II molecules
- bind peptide fragments to MHC-II molecules
- insertion of antigen-MHC-II complexes into plasma membrane
Steps of endogenous antigen presentation:
- digest antigen into peptide fragments
- synthesis of MHC-I molecules
- binding of peptide fragments to MHC-I molecules
- packaging of antigen MHC-I complexes
- insertion of antigen MHC-I complexes into plasma membrane
T cells are usually…
inactive
T cells are activated when it…
binds to foreign antigen
How do cytotoxic T cells kill target cells?
release perforins (makes a hole) and granzymes (enter via hole and destroy cell)
Antibody mediated immunity is carried out by…
B cells, which get activated in the spleen, lymphoid nodule, or lymph node in the presence of a microbe
Structure of antibodies match those of…
antigens, just like a lock and key
Antibodies are also known as…
immunoglobulins
Antibodies has 4 polypeptide chains:
- 2 heavy chains
- 2 light chains
- hinge region: flexible
- stem region
- in H and L region, there are variable and constant regions
Variable region in H and L area of antibodies is the…
antigen binding site
Constant region in H and L area of antibodies is the…
same in all antibodies of the same class
T cells mature in thymus under…
positive and negative selection pressures
Positive selection process for maturation of T cells:
selects T cells that can recognize self-MHC proteins
- those who can’t be recognizes are destroyed by apoptosis
Negative selection process for maturation of T cells:
prompts apoptosis of T cells that bind to self antigens displayed by self-MHC
- clonal deletion ensures self-tolerance
Antibody functions as…
- neutralizing antigen
- agglutinating antigen
- precipitating antigen
- activating complement
- opsonization
Adaptive immunity can be acquired via…
- active
- passive
What happens during active adaptive immunity?
person’s own immune system responds to microbe
What happens during passive adaptive immunity?
person receives antibodies from another person or animal
- only temporary because no memory cells
Active and passive adaptive immunity can be either…
- natural
- artificial
Natural actively acquired immunity develops when…
person is exposed to antigen by chance
- ex: getting the flu
Artificial actively acquired immunity develops when…
person gets vaccines
Natural passively acquired immunity comes from…
mother to fetus
- placenta: IgG
- breast milk: IgA
Artificial passively acquired immunity develops when…
one receives serum containing antibodies
- from person or animal that has been vaccinated
Process of self recognition:
- self recognition
2. self tolerance
Loss of self tolerance during self recognition leads to…
autoimmune disorders
Two types of allergic reactions:
- immediate hypersensitivity
- delayed hypersensitivity
What are naive immunocompetent B and T cells?
cells that are not yet exposed to antigens
- called CD4 or CD8
Naive immunocompetent B and T cells are exported from…
primary lymphoid organs (bone marrow and thymus) to secondary lymphoid organs
Major types of APCs:
- dendritic cells
- macrophages
- B cells
Negative affects of immune response:
- autoimmune diseases
- allergic reactions
Autoimmune diseases result when…
immune system loses ability to distinguish self from foreign
Autoimmunity is the production of…
autoantibodies and sensitized Tc cells that destroys body tissues
Rheumatoid arthritis:
autoimmune disease that destroys joints
Myasthenia gravis:
autoimmune disease that impairs nerve-muscle connections
Multiple sclerosis:
autoimmune disease that destroys white matter myelin
Graves’ disease:
autoimmune disease that causes hyperthyroidism
Type 1 diabetes mellitus:
autoimmune disease that destroys pancreatic cells
Systemic lupus erythematosus (SLE):
autoimmune disease that affects multiple organs
Glomerulonephritis:
autoimmune disease that damages kidney
The two types of hypersensitivities are distinguished by…
- time course
- whether antibodies or T cells are involved
When antibodies are involved in an allergic response, it causes…
immediate or subacute hypersensitivities
When T cells are involved in an allergic response, it causes…
delayed hypersensitivity
Steps of immediate hypersensitivities:
- initial contact w/ allergen and sensitizes person
- activated IgE against antigen binds to mast cells and basophils
- later encounter with same allergen causes flood of histamine release from IgEs, which results in induced inflammatory response
Systemic response during immediate hypersensitivity leads to…
anaphylactic shock, which is usually seen with injected allergens
Subacute hypersensitivities are caused by…
IgM and IgG transferred via blood plasma or serum
Subacute hypersensitivities have a _____ onset and a ____ duration
short, long
Example of cytotoxic reactions:
mismatched blood transfusion
Example of immune complex hypersensitivity:
systemic lupus
Delayed hypersensitivity depends on…
helper T cells
TB test depends on what kind of reaction?
delayed hypersensitivity
Example of delayed hypersensitivity?
poison ivy reaction
