Immune Response & Inflammation (Part 1)- Exam 3 Flashcards
What is the immune system?
System that protects individual against invasion by microorganisms
What is important about immunity in regards to normal body tissue?
Must recognize and destroy invaders, BUT do no damage to normal body tissue
How does the immune system destroy invaders?
Destruction by phagocytosis and/or membrane lysis
Where does destruction of the foreign invader occur?
Takes place at the point of infection; must have ability to activate and move all components to the site
How does the immune system move all components to the site of infection?
Vascular system, lymphatic system, interstitial fluid
Who are the major players in the immune response?
WBCs, Antibody, Complement System (variety of chemical mediators)
Antigen
Anything foreign that enters the body; can bind to antibody and/or can bind to receptors on the T or B cells
Target Cells
antigenic cells that will be destroyed by immune system
Immunogen
any substance that can stimulate an immune response; all are antigenic (can bind with antibody); not all antigens are immunogens
Are all immunogens antigenic (can bind with antibody)?
Yes
Are all antigens also immunogens?
No
Pathogen
antigen with ability to cause disease; usually microorganism or toxin
What are 4 different types of antigens?
Microorganisms
Allogenic cells
Malignant cells
Infected cells
What are some examples of microorganism antigens?
Bacteria, viruses, parasites, fungi, yeasts
What are allogenic cells?
Cells from genetically dissimilar individual
Describe infected cells.
Cells inhabited by viruses, certain bacteria, parasites
How many circulating WBCs does the average adult have?
75 billion
What is the normal WBC count?
5,000 - 10,000 per mL
What percent of total leukocytes are neutrophils?
40-75% of total
What are the first leukocytes to destroy invaders?
Neutrophils
What percent of total WBC count are lymphocytes?
20-45 % of total
What are two examples of lymphocytes?
T cells/ B cells
What percent of total WBC count are monocytes?
Up to 8%
What percent of total WBC count are eosinophils?
1 - 6 %
What percent of total WBC count are basophils?
Up to 1%
What types of leukocytes are most numbers? What are they named after?
Granulocytes; names for granules in the cytoplasm
What are three examples of granulocytes?
Neutrophils
Basophils
Eosinophils
What do monocytes become in the body tissues?
Macrophages
What are large white cells?
Monocytes
What do lymphocytes differentiate into?
B and T Cells
Where are neutrophils made?
Hematopoietic marrow
What is the life span of a neutrophil?
hours to days
What percent of neutrophils circulate?
50%
What percent of neutrophils adhere to blood vessel wall?
50%
What happens to neutrophils during inflammation?
Blood vessels are leaky; neutrophils slip into interstitial space
What is margination?
accumulation and adhesion of leukocytes to the epithelial cells of blood vessel walls at the site of injury in the early stages of inflammation
Describe the neutrophils that adhere to the blood vessel wall.
Margination
Ready to move into tissues
What is the function of neutrophils?
Phagocytosis
How many neutrophils do we produce per day?
100 billion per day
What is the diameter of a neutrophils?
10-15 microns
What are the first cells to enter infected areas?
Neutrophils
What attracts neutrophils to the infected areas?
Chemotaxis
Once the neutrophil is attracted to the infected area, what happens?
Phagocytize invading organism
They die at the site
Phagocytized by macrophages
What attracts macrophages to the phagocytized neutrophil/invader complex?
Chemotaxis, but slow to respond because they’re bigger. “Clean up crew”
Where do eosinophils develop and mature?
Hematopoietic marrow
Where do eosinophils appear?
Where foreign protein and parasites are
What are eosinophils primarily responsible for?
Destruction of parasites
What cells are involved in allergic reactions?
Eosinophils
What do eosinophils have binding sites for?
Specific antibodies; complement proteins
Eosinophils are designed to destroy cells coated with which antibodies?
IgG antibodies, IgE antibodies, and complement proteins
Where do eosinophils reside in the body?
Reside in tissues: skin, bronchi, bronchioles
What do eosinophils release?
Antitoxin (major basic protein); to destroy organisms
What type of cell is very effective against parasitic worms?
Eosinophils
What is the lifespan of an eosinophil?
12-24 hours
What is the least common granulocyte?
Basophil
What type of activity do basophils have?
Chemotaxis and phagocytic activity
What is the main function of basophils?
Release of heparin in areas of foreign invasion to prevent blood clots from forming
What cell releases heparin?
Basophils
Why would blood clots be bad in areas of foreign invasion?
Blood can’t circulation
WBC cannot get to foreign organism to destroy
Would result in tissue necrosis
What granulocytes release histamine?
Basophils
What does the release of histamine cause?
Blood vessel dilation
Where are basophils found in the body?
Circulate in the blood
What antibody do basophils have receptors for?
IgE
What cells are basophils similar to?
Mast cells
What do mast cells contain?
Histamine granules
What antibody to mast cells have surface receptors for?
IgE
Do mast cells circulate in the body?
No, they do not circulate
Where are monocytes/macrophages produced?
Bone marrow
Where are monocytes found in the body?
They circulate immature (monocytes)
Where do monocytes mature into macrophages?
When they leave blood and travel to the tissues
How are macrophages different from monocytes?
Macrophages are mature monocytes.
They are actively phagocytic
Where are macrophages concentrated?
Liver sinusoids, spleen, lungs (think of areas where you need a lot of phagocytosis)
What is the diameter of macrophages?
12-20 micrometers
How long are monocytes in the blood?
1-2 days
How long are macrophages in the tissues?
Months to years
What cells are responsible for specific immune response when antigens invade?
Lymphocytes
When are lymphocytes activated?
When they recognize foreign matter
Where are lymphocytes found?
Circulating in the blood
Where do lymphocytes wait for antigens to appear?
Lymph nodes
What cells play a role in rejection of organ transplants?
Lymphocytes
Where do T-lymphocytes (T-cells) mature?
Thymus
What do T-cells “learn” in the thymus?
learn to recognize self; attack self tissues
What do membrane receptors on T-cells bind?
Protein antigens; need to recognize certain fragments of protein antigens
What is an example of an “antigen presenting cell”?
Macrophage
What do antigen presenting cells do?
Digest and display a peptide fragment on cell surface that T-cells can recognize
What happens once T-cells recognize the foreign invader?
It binds the antigen; releases cytokines
What’s another name for cytokines?
Interleukens
What are the 4 different types of T-cells?
Helper T-cells
Cytotoxic T cells
Suppressor T cells
Memory T cells
What are the protein molecules of antibodies?
Immunoglobulins
What are antibodies produced by? In response to what?
B lymphocyte cells (plasma cells); in response to a specific antigen
After initial exposure to an antigen, how long does it take for antibodies to reach full power? (aka lag time)
14 days
Where are antibodies always present in small amounts?
Blood and body tissues
What are the five classes of antibodies?
IgG IgM IgD IgA IgE
What must antibodies bind with to be effective?
Outer surface of the antigen; antigen binding site unique
Can antibodies cross cell membranes?
No
What are the functions of antibodies?
Opsonize antigen (mark antigen for destruction) Activate complement cascade
The surface of what cells trigger production of antibodies?
B cells
What do T cells do?
Help B cells make antibodies; control immune response; release cytokines and chemical mediators
What 4 regions do all antibodies generally have?
Antigen-binding site
Light chains (Variable region)
Heavy chains
Transmembrane region
What do the immunoglobulins do?
Help B- Cell communicate with the interior of the cell; help bring the signal in
What do B-cells give rise to after an encounter with an antigen?
Antibody-secreting plasma cells
During development, progenitor cells give rise to what?
Large numbers of lymphocytes each with a different specificity
What happens with small lymphocytes one they are activated by a pathogen?
Proliferation and differentiation of pathogen-activated lymphocytes to form a clone of effector cells
What is the coating of antigen with antibody and complement called?
Opsonization
What is the purpose of opsonization?
Provides targeting mechanism for the phagocytic neutrophils and macrophages allowing them to bind, engulf, and destroy the antigen
What process provides points where phagocytes can attach to the antigen?
Opsonization
What are the two specific receptors on the membrane surface of phagocytic cells?
Fc receptor
C3 receptor
What does the Fc receptor do?
Binds with an antibody; it is a specific receptor on the membrane surface of phagocytic cells
What does the C3 receptor do?
Binds with complement; it is a specific receptor on the membrane surface of phagocytic cells
What is the general process for antigen destruction mediate by antibody?
Opsonization
Lysis
Antibody-dependent cell-mediated cytotoxicity
Neutralization
How does lysis occur?
Complement activation leads to the production of the membrane attach complex (MAC)
The MAC will lyse the antigens membrane
How does antibody-dependent cell-mediated cytotoxicity occur?
Cell destruction carried out by natural killer cells, macrophages, neutrophils, and eosinophils of target cells opsonized by antibody
What is neutralization?
Antibody renders the antigen toxins harmless
What two antibody classes do most antibodies fall into?
IgG or IgM
What is antibody class determined by?
Amino acid arrangement in heavy and light chains (same arrangement in specific area of chain)
What is the first antibody produced against an antigen by the B cells/plasma cells?
IgM
What do increased levels of IgM indicate?
New infection
What is the first antibody produced by the fetus?
IgM
What do increased levels of IgM indicate in a newborn?
Infection
What percent of circulating antibodies are IgM?
10-15%
Where are IgM found in the body?
Remain in the vascular system; very large
What is the main function of IgM?
Activate the complement system
What can IgM antibodies cause?
Antigen agglutination (platelets; cold agglutinins)
What type of antibodies are Anti-A and Anti-B antibodies? (Blood type)
IgM
What is the second class of antibody to be released?
IgD; not much is known about this class
Where are IgD antibodies found?
Found in small amounts in serum and body fluids
What effect do IgD antibodies have on the antigen?
Has little immunologic effect
What may IgD antibodies assist with?
Maturation of B cells into plasma cells; but not sure how
What is the third class of antibodies to be released?
IgE
Where are IgE antibodies found?
Very low concentrations in the plasma
When do IgE antibody levels increase?
Allergic reactions and parasitic infections
What is the causative agent for asthma, hay fever, and other allergic reactions?
IgE antibodies
What do IgE antibodies bind with?
Basophils and mast cells stimulating them to release histamine
What antibody is involved with anaphylactic reactions?
IgE
What is the fourth class of antibodies to be released?
IgG
What is the most important and most potent class of antibodies to be released?
IgG antibodies
What percent of antibodies are IgG?
80% of antibody in the immune system
When are IgG antibodies produced in greatest amounts?
Upon second exposure to the antigen
What is the only antibody that can cross the placenta? What is its function?
IgG; provides immunologic protection for fetus
What type of antibody is Rh? What is the significance of this?
IgG, crosses the placenta, can result in hemolytic disease of the newborn
What is hemolytic disease of the newborn?
Disease where mother’s body attacks baby via IgG antibodies; second exposure when mother is Rh- and baby is Rh+
What are IgG antibodies very effective at?
Binding and destroying antigens
What are the four subgroups of IgG antibodies?
IgG1, IgG2, IgG3, IgG4
What does IgG1 do?
Protects body form (most) bacteria
What does IgG2 do?
attacks and destroys organisms encase in a saccharide coat (i.e. rest of bacteria)
What does IgG3 do?
Activates complement proteins, enhances phagocytosis of antigen
What does IgG4 do?
produce potent vasodilators, protects bronchioles
What is the major antibody in the body fluids and mucous secreted by the mucous membranes?
IgA antibodies
Where are IgA antibodies found?
Tears, breast milk, bronchiole secretions, saliva
What is the effect of IgA antibodies binding with antigen?
Immobilizes it; allows mucin to remove antigen-antibody complex
Mucin
main ingredient of the mucous
Can IgA antibodies activate the complement system?
No.
What can IgA antibodies trigger?
Cell-mediated immune reactions
What is the heaviest antibody?
IgM
Which antibodies have the longest half-life in serum?
IgG1, IgG2, IgG4 (not IgG3)
Which antibody has the shortest half-life?
IgE
Which antibodies have the greatest effect in opsonization?
IgG1 antibodies
Which antibodies have the greatest effect in sensitization of mast cells?
IgE antibodies
Which antibodies have the greatest activation of hte complement system?
IgM, IgG3
Which antibodies have the greatest transport across the epithelium?
IgA
Which antibodies have the greatest transport across the placenta?
IgG1, secondary: IgG3
Which antibodies have the greatest diffusion into extravascular sites?
All the IgG’s
What are the two categories of immunity?
Innate
Adaptive
What is the innate immunity?
Inborn/natural
First line of defense- always present; able to respond quickly
What are the components of innate immunity?
Epithelial barriers, phagocytes, complemetn, natural killer cells
How does the innate immunity detect an antigen?
General recognition mechanisms; recognizes microorganisms, limited number of recognition proteins available
Does innate immunity produce long term immunity to an antigen?
No
Innate immune system response results in what?
Inflammation
What is adaptive immunity?
Responds to specific antigen; can be non-microbial
How many recognition proteins does adapative immunity have?
Millions
When does adaptive immunity develop?
After exposure to antigen; slow response; very powerful response
What are the major players of adaptive immunity?
Lymphocytes: T and B cells
What are the characteristics of adaptive immunity?
Specificity Diversity Memory Self-regulation Self-tolerance
What is specificity?
Immune reaction specific for offending antigen
What is diversity?
Lymphocytes can response to millions of antigens
What is memory in regard to adaptive immunity?
Lymphocytes can remember any antigen previously encountered
What is self-regulation?
Lymphocytes can shut down activity after antigen is destroyed
What is self-tolerance?
Lymphocytes can distinguish self-tissue from non self tissue
What are the recognition mechanisms for innate immunity?
Rapid response (hours)
INvariant
Limited number of specificites
Constant during response
What are the recognition mechanisms for adaptive immunity?
Slow response (days to weeks)
Variable
Numerous highly selective specificities
Improve during response
When is the immune response initiated?
When antigen stimulates activation of T and B cells
What are the phases of immune response?
Cognitive Phase (First phase) Activator Phase (second phase) Effector phase (third phase)
What is the cognitive phase?
Antigen interacts with the T lymphocytes
What is the activator phase?
T cells respond by releasing cytokines
Cytokines stimulate proliferation of T and B cells
What is the effector phase?
Granulocytes, macrophages, complement activated
Antigen opsonized and engulfed
What kind of response do T Lymphocytes induce?
direct immune response against protein antigen
What type of cells are responsible for the type of white cells that response and how they response?
T lymphocytes
What is the job of the T cell?
Recognize the antigen; assist phagocytosis via release of cytokines that activate other phagocytic cells; destroy malignant cells, allogenic cells nad infected cells via lysis; aids B cells/ plasma cells in antibody production; delayed hypersensitivity immune reactions; graft rejection in organ and tissue transplantation, autoimmune disorders
T cells response to antigen is called what?
Cell-mediated immunity
Where are T cells produced?
Bone marrow
When T cells leave the thymus, which secondary lymphatic organs do they travel to?
Lymph nodes
Spleen
Tonsils
How are T cells categorized?
Protein molecules on cell membrane (CD8+ / CD 4+)
MHC
Major Histocompatibility Complex
Describe the intracellular antigen complex with T-cells?
MHC class I molecules bind to CD8
Describe the extracellular antigen complex with T-cells?
MHC class II molecules bind to CD4
What are 3 types of T cells?
Cytotoxic cells
Helper cells
Suppressor cells
CD8
Cytotoxic T cells
What must CD8 be converted from?
Inactive T cells
What is the function of CD8 cells?
Destroy virally infected cells, allogenic cells (organ transplant), malignant cells. Once they activate, release lytic molecules that rupture target cells
What is the function of CD4 cells?
Assist or activate other white cells; release cytokines to call other cells
Do CD4 cells destroy the antigen directly?
No
When are CD4 cells activated?
When presented with antigen-MHC-combination
Where is MHC found?
Found on most body cells
What types of MHC are there?
Class I or Class II
What does MHC do?
Binds with antigen fragments
What are the two subsets of Helper T cells (CD4)
TH1
TH2
CD4
Helper T cells
TH1
Inflammatory helper; recognizes complex of peptide antigen with MHC class II and activates macrophage; release cytokines that convert inactive T cells into cytotoxic T cells
TH2
Release cytokines needed for B cell activation and antibody secretion; must be present; recognizes complex of peptide antigen with MHC class II and activates B cell
Why are suppressor T cells activated?
To stop immune response once antigen has been destroyed
What do B Lymphocytes do?
Produce antibody in response to antigen
Able to directly recognize carbohydrate and lipid antigens and initiate response
What type of immunity are B lymphocytes associated with?
Humoral Immunity
How are B Lymphocytes acitvated?
TH2 helper cells; must be activated before it can produce antibody against protein antigen
What happens when B Lymphocytes are activated?
Proliferate and differentiate into plasma cells; plasma cells produce the antibodies for the specific antigen; antibody will be produced until antigen has been destroyed
Where are dendritic cells?
In Skin
What is an antigen digested into?
Small peptides
