Brock Immunity Reading Flashcards
The body’s built in ability to recognize and destroy pathogens or their products
Develop within hours after contact with pathogen
Function of phagocytes
Innate immunity
Cells that can ingest, kill, and digest most microbial pathogens
Play a big role in innate immunity
Phagocytes
The acquired ability to recognize and destroy a specific pathogen or its products
Activated by innate response phagocytes
Directed at unique pathogen molecules called antigens
Takes several days to develop
Adaptive immunity
Unique pathogen molecules
Antigens
Phagocytes present antigen molecules to these cells
Key cells in the adaptive response
Antigens bind specific receptors on these cells
Lymphocytes
What doors the process of antigens binding specific receptors on the lymphocyte result in?
Triggers genes that promote lymphocyte multiplication and production of pathogen specific proteins that interact with the pathogen, marking it for destruction
Cells active in innate and adaptive immunity develop from common precursors called….
Grow in the bone marrow
Stem cells
What does immunity primarily result from?
The actions of cells that circulate throughout the body, mainly through the blood and the lymph
A fluid similar to blood that has nucleated cells and proteins but lacks red blood cells
Lymph
Precursor cells that can differentiate into any blood cell
Multipotent stem cells
How do stem cells differentiate into a variety of mature cells?
Under the influence of soluble cytokines and chemokines
Proteins that influence many aspects of immune cell differentiation
Cytokines and chemokines
Most numerous cells in human blood
Nonnucleated cells that function to carry oxygen from the lungs to the tissues
Erythrocytes (red blood cells)
Nucleated cells
Include phagocytes of the innate immune system and lymphocytes of the adaptive immune response
Leukocytes (white blood cells)
What does human blood consist of?
Red blood cells
White blood cells
Plasma
Include the phagocytes of the innate immune response
Leukocytes
The cells active in the adaptive response
Lymphocytes
A liquid containing proteins and other solutes
In the blood
Plasma
The remaining fluid after blood clots, which has no cells or clothing proteins
Has a high concentration of antibodies
Serum
Soluble immune proteins that bind pathogen antigens
Antibodies
How does blood travel?
Blood is pumped by the heart through arteries and capillaries throughout the body and is returned through the veins
A separate circulatory system containing lymph
Lymphatic system
How does lymph drain?
Drains from extravascular tissues into lymphatic capillaries, lymph ducts, and then into lymph nodes throughout the lymphatic system
Organs that have lymphocytes and phagocytes arranged to encounter micro organisms and antigens as they travel through the lymphatic circulation
Lymph nodes
Part of the lymphatic system
Interacts with antigens and micro organisms that enter the body through mucous membranes, including those of the gut, the genitourinary tract, and bronchial tissues
Contains phagocytes and lymphocytes
Mucosa-associated lymphoid tissue (MALT)
Consists of the lymph nodes, MALT, and spleen
Sites where antigens interact with antigen presenting phagocytes and lymphocytes to generate an adaptive immune response
Secondary lymphoid organs
Nucleated white blood cells found in the blood and the lymph
Participate in adaptive immunity
Leukocytes
Active in innate immunity
Derived from myeloid precursor cells
Myeloid cells
What two lineages can mature myeloid cells be divided into?
Monocytes and granulocytes
What does the monocyte lineage develop into?
Specialized phagocytic cells, called the antigen presenting cells (APCs)
Engulf, process, and present antigens to lymphocytes
Derived from monocyte lineage
Include macrophages and dendritic cells
Antigen presenting cells
Usually the first defense cells that interact with a pathogen
Abundant in spleen, lymph nodes, and MALT
derived from monocytes
Macrophages
Phagocytes that specialize in presenting antigens to lymphocytes
Derived from monocytes
Dendritic cells
Second lineage derived from myeloid precursors
Contain cytoplasmic inclusions, or granules
Granulocytes
Contain toxins or enzymes that are released to kill target cells
Granules
Granulocyte with phagocytic activity
Called a polymorphonuclear leukocyte (PMN)
Central to innate immunity
Neutrophil
Release of granules
Can cause allergy symptoms and inflammation
Degranulation
Specialized leukocytes involved exclusively in the adaptive immune response
Lymphocytes
Circulate through the blood and lymph system but are concentrated in the lymph nodes and spleen where they interact with antigens
Mature lymphocytes
What are the two types of lymphocytes?
B cells
T cells
Type of lymphocyte
Originates and matures in the bone marrow
Specialized APCs
Precursors of antibody producing plasma cells
B cells
Called immunoglobulins (Igs)
Soluble proteins produced by B cells and plasma cells
Interact with certain antigens
Antibodies
Type of lymphocyte
Interact with antigen
Begin development in the bone marrow but travel to the thymus to mature
T cells
Consists of the bone marrow and thymus
Sites where lymphoid stem cells develop into functional antigen-reactive lymphocytes
Primary lymphoid organs
Process of leukocytes moving throughout the body and passing from blood to interstitial spaces, then to lymphatic vessels, and back to the blood circulatory system
Extravasation
The non-inducible, preexisting ability to recognize and destroy a pathogen or its products
Does not require previous exposure to a pathogen
Mediated by phagocytes
Innate immunity
What do the macromolecules inside and on the surface of pathogens display?
Pathogen associated molecular patterns (PAMPs) ~ have repeating subunits
What is the first line of defense against pathogens the body has never encountered?
Phagocytes such as macrophages and neutrophils
What do phagocytes have that interact directly with PAMPs?
Pattern recognition receptors (PRRs)
How do PRRs work?
Each PRR interacts with a certain PAMP to activate the phagocytes to ingest and destroy the targeted pathogen by phagocytosis
Directed toward a molecular component of the pathogen called an antigen
Pathogen specific receptors are made in large numbers only after exposure to the pathogen or its products
Inducible only when triggered by a unique antigen on a pathogen
Adaptive immunity
What is generated during the first exposure to an antigen?
Primary adaptive immune response
The Antigen contact stimulates growth and multiplication of antigen reactive cells, creating clones, which are large numbers of identical antigen reactive cells
Clones persist for years and confer long term specific immunity
Primary adaptive immune response
The antigen binding proteins of T cells
T cell receptors (TCRs)
Cell surface antibodies on a B cell
B cell receptors (BCRs)
Caused by a second exposure to the same antigen which activates the clones of antigen reactive cells
Faster and stronger response
Secondary adaptive immune response
The rapid increase in adaptive immunity after a second antigen exposure
Memory
Exhibited by the adaptive immune system
The acquired inability to generate an immune response against self antigens
Ensures that adaptive immunity is directed to outside agents that pose genuine threats to the host, and not to host proteins
Tolerance
What does adaptive immunity begin with?
The interactions of immune T lymphocytes with peptide antigens on infected cells
When can a T cell recognize peptides?
The T cell, with its TCR, can recognize peptide only when the peptides are complexed with self proteins called major histocompatibility complex (MHC) proteins, found on host cell surfaces
What displays MHC 1 proteins?
All host cells
What cells display MHC 2?
APCs (macrophages, dendritic cells, B cells)
Where are the APCs found?
Macrophages ~ all organs of the body
Dendritic cells and B cells ~ secondary lymphoid organs
Process of MHC-embedded peptides being transported to the phagocyte surface where the complex is displayed
Antigen presentation
How do T cells grow and divide?
Peptide-MHC complexes that interact with the TCR signal the T cell to grow and divide,producing antigen reactive clones that interact directly to kill cells displaying the same foreign peptide or help other cells to eliminate cells with the same peptide
What are the three basic T cell subsets?
*t cell subsets interact with other cells to initiate immune reactions
1) . T-helper cells (Th)
- Th1
- Th2
2) . T-cytotoxic (Tc) cells
Differentiated from Th cells
Antigen activated T cell subsets
Respond by proliferating and producing soluble cytokines which interact with receptors on other cells, activating them to initiate an immune response
Th1 and Th2 cells
Interact with peptide-MHC 2 complexes on the surface of macrophages stimulate the Th1 cell to make cytokines that activists the macrophages, enhancing phagocytosis of cells displaying the target peptide and causing inflammatory reactions that limit the spread of infections
Antigen specific Th1 cells
Use cytokines to stimulate (help) antigen reactive B cells to make antibodies
Th2 cells
Recognize the peptide-MHC 1 complex on an infected cell
When they interact with the infected cell, they secrete proteins that kill the peptide bearing infected cell
T-cytotoxic cells (Tc)
Soluble proteins made by B cells and plasma cells in response to exposure to antigens
Bind specifically to a single antigen
Antibodies
Controls the spread of infection by recognizing pathogens and their products in extra cellular environments like blood and mucous secretions
Antibody mediated immunity
Specialized lymphocytes that have antibodies on their surface
Each one displays multiple copies of a single antibody that is specific for a single antigen
B cells
How are antibodies made?
B cells bind antigens through interactions with the BCR
The surface antibody-antigen interaction induces the B cell to ingest the antigen containing pathogen by phagocytosis
The B cell then kills and digest the pathogen, producing a battery of pathogen derived peptide antigens
The peptides are complexed with MHC 2 and displayed on the surface of the B cell to the antigen specific Th2 cell
What do Th2 cells produce?
Cytokines that stimulate antigen reactive B cells, which respond by growing and dividing, establishing clones of the original antigen reactive B cell
Many of the activated B cells differentiate into plasma cells that make soluble antibodies
The secondary response
Basis for vaccination
Immune memory
Antibody class
Found in blood and mucous secretions
Functions in secondary response and mucosal immunity for extracellular pathogens
IgA
Antibody class
Found in mast cells
Functions in parasite immunity and allergies
IgE
Antibody class
Found in the blood
Functions to secondary response for extracellular pathogens
IgG
Antibody class
Found in the blood
Functions in primary response for extracellular pathogens
IgM
How do antibodies work?
Most antibody interactions don’t directly kill the pathogen
Many antibodies block interactions between pathogens or their products and host cells
Specific serum antibodies can bind toxins, blocking the binding of toxin to host cell receptors
Neutralization
Have general antibody receptors called Fc receptors (FcR) that bind to any antibody attached to an antigen
Phagocytes
Enhanced phagocytosis of the antibody coated cells
Opsonization
What might antibody mediated destruction of pathogens also involve?
A group of proteins known collectively as complement
How do complement proteins work?
Complement proteins attach to pathogen surfaces, attracted by IgM or IgG antibodies bound to the pathogen
What two effects could the complement proteins haven on the pathogen?
1) . Complement proteins could form a pore in the pathogen cytoplasmic membrane, directly lysing the pathogen cell
* only affects those pathogen cells with bound antibodies
2) . The stimulation of phagocytosis; pathogen bound complement proteins are recognized by complement receptors called C3 receptors (C3R) found on the surface of phagocytes like neutrophils and macrophages
* results in opsonization and phagocytosis of the cells sensitized by antibody and complement
A general, nonspecific reaction to noxious stimuli such as toxins and pathogens
Characterized by redness, swelling, pain, and heat usually localized at the site of infection
Inflammation
What are the molecular activators or inflammation?
Group of cell activators and chemoattractants, including cytokines and chemokines
Cells with inflammation inducing abilities
Produced in high concentration by phagocytes and lymphocytes
The most important chemokines and cytokines
Proinflammatory
Why does an immune response normally activate inflammation?
To isolate and limit tissue damage by destroying pathogen invaders and removing damaged cells
An acute condition that begins at the site of pathogen entry into the body
Immune mediated inflammation
What happens if the inflammatory response fails to localize the pathogens?
The reaction spreads throughout the body
Uncontrolled systemic inflammation can be more dangerous than the Original infection
Can lead to septic shock
IL-1, IL-6, and TNF-alpha
Endogenous pyrogens
Proinflammatory cytokines
Stimulate the brain to produce prostaglandins, chemical signals that raise body temperature, causing a fever
Endogenous pyrogens
High fever
Extremely low blood pressure
Severe edema
Caused by a high quantity of projnflammatory cytokines meant to combat systemic infections
Septic shock
Fragment of antigen binding
FAB
Increased oxygen species
Increased hydrolytic enzymes
Decreased pH
Increased antimicrobial peptides
Effects of phagocytosis
Involve phagocytes, macrophages, phagolysozome, phagosome, lysozome
Intracellular defense
Involve neutrophils, granules, NETS
Extracellular defense
True or false: both myeloid cells and lymphoid cells are leukocytes?
True
True or false: primary lymphoid organs are places where leukocytes clear infections; secondary lymphoid organs are placed where leukocytes are generated
False
True or false: phagocytes are myeloid lineage cells
True
True or false: LPS composition is the same in all bacteria?
False
True or false: primary adaptive immune response takes place in primary lymphoid organs; secondary adaptive immune response takes place in secondary lymphoid organs?
False
True or false: antigen presenting cells are pathogens that have pathogen associated molecular patterns on their surface?
False
True or false: the presence of pathogens is enough to stimulate antibody production?
False
True or false: antibodies do not directly kill pathogens
True
True or false: during septic shock, the blood pressure is likely lower?
True
