Immune response part 1 Flashcards
define immunity
System that protects individual against invasion by microorganisms and foreign substances
what must immunity be able to do
Must recognize and destroy invaders – BUT do no damage to normal body tissue
– destruction by phagocytosis and/or membrane lysis – destruction take place at point of infection
ability activate and move all components to the site (vascular system / lymphatic system / interstitial fluid)
major players in immune system
white blood cells, antibody and the 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
pathogen
– antigen with ability to cause disease – usually microorganism or toxin
– antigen examples
Microorganisms – bacteria / viruses / parasites / fungi / yeasts
Allogeneic cells – cells from genetically dissimilar individual
Malignant cells Infected cells
– cells inhabited by viruses / certain bacteria / parasites
leukocytes/wbc normal count
Avg adult has 75 billion circulating WBCs
NORMAL COUNT: 5,000 to 10,000 per mL
leukocytes by percentage
Neutrophiles: 40 to 75% of total
Lymphocytes: 20 to 45% – T Cells / B Cells
Monocytes: Up to 8% Eosinophils: 1 to 6% Basophils: Up to 1%
key leukocytes
Granulocytes: Most numerous, named for granules in cytoplasm
– Neutrophils – Basophils – Eosinophils
Monocytes: large white cells, become macrophages in body tissues
Lymphocytes: differentiate into B- and T- cells
neutrophil production site, life span, how many circulate adhere to wall, fxn.
Made in hematopoietic marrow Life span = hours to days 50% circulate
50% adhere to blood vessel wall – Margination – Ready to move into tissues
Fxn: phagocytosis
neutrrophil how many produced, diameter, how they function
Produce about 100 billion per day
10-15micrometer diameter
First to enter infected areas – Attracted via chemotaxis – Phagocytize invading organism – Die
– Phagocytized by macrophages
Granulocytes: Eosinophils site of production, where they appear, what they cells they destroy with what type of antibodies?
Develop and mature in hematopoietic marrow
Appear where foreign protein and parasites are
Involved in allergic reactions Have binding sites for specific antibodies
and complement proteins
– Designed to destroy cells coated with IgG antibodies, IgE antibodies and complement proteins
Granulocytes: Eosinophils where they reside, what they release, lifespan, especially effective against?
Reside in tissues – Skin, bronchi, bronchioles
Release antitoxin (Major Basic Protein) to destroy organisms
Very effective against parasitic worms Lifespan = 12-24 hours
Granulocytes: Basophils commonness, main fxn. , what kind of activity do they display
Least common
Have chemotaxis and phagocytic activity
Main fxn: release of heparin in areas of foreign invasion to prevent blood clots from forming
– Blood clots – blood can’t circulate – WBC cannot get to foreign organism to destroy – tissue necrosis
Granulocytes: Basophils what they release, where they circulate, receptor type, similar to mast cells how?
Also release histamine – Causes blood vessel dilation
Circulate in blood
Have receptors for IgE antibody.
Similar to mast cells. – Also contain histamine granules – Also have surface receptors for IgE antibody – Do Not Circulate
Monocytes / Macrophages production site, circulation process, diameter, lifespan in blood/tissue
Produced in bone marrow
Circulate immature
Leave the blood and travel to the tissues – Mature into macrophages
Actively phagocytic – Concentrated in liver sinusoids, spleen, lungs
12-20 micrometers
Monocytes in blood for 1-2 days
Macrophages in tissues for months to years
lymphocytes fxn.
Specific immune response when antigen invades
Activated when they recognize foreign matter
Circulate in blood Wait in lymph nodes for antigens to
appear
Play a role in rejection of organ transplants
T-Lymphocytes (aka. T-Cells) maturation process, receptor,relationship between macrophages, what they release
Mature in thymus – Learn to recognize self
Attack self tissues – destroyed Membrane receptors on T-Cells bind
protein antigens
– Need to recognize certain fragments of protein antigens
Antigen presenting cells (ie. Macrophage) digest and display a peptide fragment on cell surface that T-cells can recognize.
Once T-Cells recognize – bind antigen – Release cytokines (interleukins)
Different types of T-cells:
– Helper T-Cells – Cytotoxic T Cells – Suppressor T Cells
– Memory T Cells
Antibody Molecules what they are, what produces them, where they are present
Protein molecules: immunoglobulin Produced by B lymphocyte cells (plasma cells) in response to a
specific antigen – after initial exposure, takes 14 days to reach full power (lag time)
Always present in small amounts – blood & body tissues
5 classes of antibody molecules and what they need to bind to
IgG; IgM; IgD; IgA; IgE Must bind with the outer surface of the antigen to be effective
– antigen binding site unique
Cannot cross cell membra
antibody molecules function
– opsonize antigen (mark antigen for destruction) – activate complement cascade
surface of B Cells Trigger
production of antibodies
t cells control
immune response
Opsonization coating,how phagocytes interact
Coating of antigen with antibody and complement
– Provides targeting mechanism for the phagocytic neutrophils and macrophages allowing them to bind, engulf, and destroy the antigen
Provides points where the phagocytes can attach to the antigen
phagocytic cells two specific receptors on membrane surface
– Fc receptor: binds with antibody – C3 receptor: binds with complement
Ways of Antigen Destruction Mediated by Antibody
Opsonization Lysis
– complement activation leads to production of the membrane attack complex (MAC)
– the MAC will lyse the antigens membrane
Antibody-dependent cell-mediated cytotoxicity
– cell destruction carried out by natural killer cells, macrophages, neutrophils and eosinophils of target cells opsonized by antibody
Neutralization – antibody renders the antigen toxins harmless
Most antibodies fall into what class and how is class determined
IgG or IgM class. class determined by the amino acid arrangements in heavy and light chains – same arrangement in specific area of chain
IgM Antibody Class first antibody….
First antibody produced against an antigen by the B cells / plasma cells
– increased levels indicate new infection First antibody produced by the fetus
– increased levels indicate infection in newborn
IgM Antibody Class SIZE, FUNCTION, what type of antibodies are include in class
Accounts for 10 to 15% of circulating antibody Very large – remains in vascular system Main function to activate complement system Can cause antigen agglutination
Anti-A and Anti-B antibodies are the IgM type Fxn: Activate Complement
IgD
Second class of antigen to be released Not much is known about this class
Found only in small amounts in serum and body fluids
Has little immunologic effect on antigen
May assist with the maturation of B cells into plasma cells
IgE Antibody Class CONCENTRATION IN PLASMA, function
Third class of antibodies released Found in very low concentrations in plasma
Increases with allergic reactions and parasitic infections
– causative agent for asthma, hay fever and other allergic reactions
Bind with basophils and mast cells stimulating them to release histamine
Involved with anaphylactic reactions
IgG Antibody Class percentage, what type of antibodies are in this class, fxn
Fourth class released Most Important Most potent
Comprises 80% of antibody in the immune system – produced in greatest amounts on second exposure to antigen
Only antibody that can cross the placenta
– provides immunologic protection for fetus
– Rh antibody is an IgG antibody Hemolytic disease of the newborn
Very effective at binding and destroying antigen
IgG SUBGROUPS and their fxn.
4 subgroups:
– IgG1- protects body from (most) bacteria
– IgG2 – attacks and destroys organizms encased in a saccharide coat
Ie. Rest of bacteria – IgG3 – activates complement proteins
Enhances phagocytosis of antigen
– IgG4 – produces potent vasodilators Protects bronchioles
IgA Antibody Class where it’s found, fxn., limitation
Major antibody in the body fluids and mucous secreted by the mucous membranes
– tears / breast milk / bronchiole secretions / saliva
Binds with antigen to immobilize it – allows mucin (main ingredient of mucous) to remove antigen-antibody complex
Cannot activate the complement system Can trigger cell-mediated immune reactions
Innate Immunity charac.
Inborn / natural
First line of defense – always present
Able to respond quickly
innate components and recognition
Components – epithelial barriers / phagocytes / complement / natural
killer cells. Uses general recognition mechanisms to detect antigen – recognizes microorganisms – limited number of recognition proteins available
Does NOT produce long term immunity to antigen
Inflammmation!!!!!!!!
Adaptive Immunity what they respond to , how fast/powerful
Responds to specific antigen – can be non microbial – millions of recognition proteins
Develops after exposure to antigen Slow response Produces very powerful response
Lymphocytes (T & B cells) are the major players
Characteristics of Adaptive Immunity
Specificity – immune reaction specific for offending antigen
Diversity – lymphocytes can respond to millions of antigens
Memory – lymphocytes can remember any antigen previously
Self-regulation – lymphocytes can shut down activity after antigen is
destroyed
Self-tolerance
– lymphocytes can distinguish self-tissue from non self tissue
initiation of immune response
Immune response initiated when antigen stimulates activation of T and B cells
– cognitive phase
(first phase) antigen interacts with the T lymphocytes
– activator phase
(second phase) T cells respond by releasing cytokines cytokines stimulate proliferation of T & B cells
– effector phase
(third phase) granulocytes / macrophages / complement activated antigen opsonized and engulfed
T cell response to antigen is called
cell mediated immunity
T cells must recognize ______ to respond
the antigen
role of T cells (7 roles)
Direct immune response Assist phagocytosis via release of cytokines that activate
other phagocytic cells Destroy malignant cells, allogeneic cells and infected
cells via lysis
Aid B cells / plasma cells in antibody production
Involved with delayed hypersensitivity immune reactions
Cause some types of graft rejection in organ and tissue transplantation
Responsible for certain types of autoimmune disorders
t cells produced where? mature where? end up in what secondary organs?
Produced in bone marrow Mature in thymus
– cells trained to distinguish self-tissue from non self-tissue
Leave thymus – travel to secondary lymphatic organs
– lymph nodes – spleen – tonsils
Types of T Cells
– cytotoxic cells – helper cells – suppressor cells
how are t cells categorized
Categorized by protein molecules on cell membrane (i.e. CD8+ / CD4+)
cytotoxic t cells destroy ______ by releasing ________
virally infected cells, allogenic cells (organ transplant), malignant cells. lytic molecules
helper t cells release
cytokines to call other cells. do not destroy directly
helper t cells activated when
presented with antigen-MHC combination
MHC stands for
major histocompatibility complex
TH1:
inflammatory helper; releases cytokines that convert inactive T cells into cytotoxic T cells
TH2
release cytokines needed for B cell activation and antibody secretion; MUST be present
Suppressor T Cells
Activated to stop immune response once antigen has been destroyed
B Lymphocytes Produce antibody in response to
antigen – called HUMORAL IMMUNITY
b lymphocytes can directly recognize
carbohydrate and lipid antigens and initiate response
B lymphocytes must be activated by ______ before it can produce antibody against protein antigen
TH2 helper cells
When activated B cells proliferate and differentiate into
plasma cells
plasma cells produce
antibodies for the specific antigen
– antibody will be produced until antigen has been destroyed
