Exam 3
The classical, alternative, and lectin pathways of complement share which one of the following?
C5
In order for fever to occur, ____ bind to receptors in the brain and cause ____ within the extremities of the body. This results in more blood volume within the body's core.
pyrogens ... vasoconstriction
In addition to T-cell receptor complexes, T cells must express surface marker ______ in order to selectively recognize an MHC class II- antigen complex on antigen- presenting cells
CD47
The following process or protein prevents phagocytes from ohfagocytizing host cells?
CD47
Type III hypersensitivities
Circulating immune complexes of antigen and antibody large in blood vessel walls (Skin, joints, kidneys) Bacterial, viral, protozoan infections Systemic lupus erythromatosus
Which of the following immune system components is considered part of the innate system?
Complement
Granulocytes
Contain cytoplasmic granules (innate cells) Neutrophils, basophils, eosinophils
Internal pyrogens
Cytokines produce by body
Chemical barriers to infection
Defensins
What is the function of a TH cell (i.e. an activated helper T cell)?
Delivery cytokines
Select the phagocytic cells that also present antigen on their surface.
Dendritic cells, macrophages
Classic pathways
Depends on antibodies, system doesn't provide immediate protection B cells produce antibody Fc tail attracts C1 Parts of C2 and C4 join to form C3 convertase
Immunodeficiency
Disorder when immune system too weak to prevent infection
Live attenuated have mutations that affect pathogenicity genes
Either grown on media for a long time or genes changed through DNA technology Microbes replicate in host, better at stimulating immune system TB, typhoid fever, chicken pox, measles, mumps, rubella
Subunit vaccines are only pieces of microbe/virus
Either purified antigen or made through DNA technology HepB, cholera, HPV, pertussis
Humoral immunity
Eliminates extracellular antigens triggered to proliferate, differentiate into plasma cells in response to extracellular antigens Some B cells with best matched BCR become memory cells
Transfusion reactions
Erythrocytes have antigenic determinate on surface Have antibodies to the antigens they lack
MHC II complexes on antigen-presenting cells are loaded with ________ produced peptides
Extracellularly
The classical, alternative and lectin pathways of complements share which one of the following?
Factor H
A 5 year old boy develops an infection with Steptococus pneumoniae, an organism encased with a thick, slippery carbohydrate capsule. Which of the following helps phagocytes engulf these organisms?
Fc receptors
Agammaglobulinemia
Few/ no antibodies are made
What are the complements more effective against?
G negative
Primary (congenital)
Genetic defect or from environmental factors that cause developmental abnormalities
5 cardinal signs of acute inflammation
Heat, edema, redness, pain, altered function/ movement
Effector helper T cells (TH cells)
Help humoral and cell-mediated immunity activate B cells, macrophages; produce cytokines to direct and support T cells
The concept whereby unvaccinated persons are protected from infection by those vaccinated in the community is called _______
Herd community
Localized allergic reaction
Hives: skin condition characterized by wheal and flare Hay fever: itching, teary eyes, sneezing, runny nose following inhalation of airborne antigen Asthma: respiratory allergy
Which of the following organs or tissues serves as the body thermostat?
Hypothalamus
CD4 helper T cells only recognize antigen displayed MHC (major histocompatibility class) class ____ molecules.
II
What is immediate hypersensitivity mediated by?
IgE
Which antibody class is associated with a secondary immune response and has the ability to cross a pregnant mother's placenta?
IgG
Autoimmuen diease
Immune responses target self tissues
Explain two reasons why a low to moderate fever is beneficial during an infection.
Increase in temperature allows immune cell metabolism to function faster
Passive immunization
Injecting Ig (ex: antitoxins), Ig passed from other to baby
Immobilization/ prevent adherence
Interferes with flagella, pili
Cytotoxic T cells target infected cells that present antigen on ______
MCH I receptors
Which markers are found on all nucleated cells?
MHC class I molecules
Lectin pathways
Macrophage cytokines cause live to release lectin Liver produces lectin, which binds to microbes Lectin cleave C4 and C2
Which of the following processes ends inflammation at a headed site of infection?
Macrophages engulf dead neutrophils
What makes inflammation stop?
Macrophages stop producing cytokines Neutrophils undergo apoptosis, programmed death with cell membrane intact Resident macrophages phagocytize dead neutrophils Fluid drains away and blood vessels return to normal
Both parts of the adaptive immune system are capable of producing memory cells. What are memory cells and why are they important?
Memory cells are long-lived cells that are produced during a primary response that reside in the body. Upon activation, these cells will have a stronger response that occurs more quickly to subsequent exposure.
Agranulocytes
Monocytes (circulate in blood) and cell types that develop as they leave the blood stream (innate cells) macrophages and dendritic cells
IgA
Monomer or dimer when secreted in saliva, mothers milk, Etc secondary component
IgG
Monomer, most abundant in blood and tissue; associated with secondary response; can cross placenta
IgE
Monomer; involved in allergic reactions and fighting parasitic worms
IgD
Monomer; involved in development/ maturation of antibody response; functions still unclear
T cells characteristics
Multiple copies of T cell receptor (TCR) Cytotoxic T cells recognize antigen on MHC class I molecules Helper T cells recognized antigen on MHC class II molecules
The best protection against a second infection by a pathogen is which of the following?
Natural infection
Why don't phagocytes kill host cell in absence of infection?
Neutrophils/ macrophages must 'see' cell surface as either self or foreign When phagocyte encounters cell, temporarily paralyzed All human cells have an inhibitory glycoprotein, CD47, on surface
Cells killed/ viruses inactivated by formalin or phenol
Not as good at stimulating immune system as live attenuated vaccines HepA, influenza, cholera
Alternative pathways
Not dependent on antibodies, much faster C3 cleaved into C3a and C3b, C5 converts splits C5
____ is the coating of encapsulated bacterial cells with antibodies or complement proteins to facilitate phagocytosis.
Opsonization
External pyrogens
Originate from 'outside' source
IgM
Pentamer, first to appear during primary response; cannot cross placenta, fetus can make but generally made about time of birth
Secondary component
Polypeptide added to dimer to protect it from enzymes in secretion
Pregnancy and hemolytic disease
Pregnant Rh - women carrying Rh + baby can develop antibodies to Rh antigen Will not affect first baby IgM Anti- Rh antibodies to second Rh + baby can cross placenta (IgG), damage fetal blood cells RhoGAM used to prevent hemolytic disease
MHC class I
Present endogenous antigens Produced by all nucleated cells
MCH class II
Present exogenous antigens Produced by antigen presenting cells (APC) (B cells, macrophages, dendritic cells)
B lymphocytes (B cells)
Produce and develop in bone marrow
Type IV hypersensitivities
Reaction takes place 2-3 days following antigen exposure, relies on sensitized T cells TB skin test poison ivy, poison oak, metal allergy
Toxoid vaccines are inactivated form of microbial toxin
Requires several vaccines, protection not long lasting Diphtheria, Tetanus
Effector cytotoxic T cells (TC cells)
Respond to intracellular antigens, induce apoptosis
Secondary (acquired)
Result of infection or other stresses on the immune system
Autoimmune diease
Results when immune system attacks 'self' antigens Treatment is difficult beaus it involved suppressing the immune system
Hemolytic disease of the new born
Rh (rhesus) antigen on red blood cells Rh + have antigen, Rh - do not Ig RH - recipient gives Rh+ blood, antibodies
Physical barriers to infections
Skin Mucous membrane Lungs
Vasodilation
Slows blood flow, neutrophils move out of vessels (extravasation), plasma moves out Cause of redness, swelling and heat
Leukocytes
Some circulate through body, some reside in tissues; numbers increases during infections
Lymphocytes
Specific in recognition of antigen (adaptive cells) B cells, T cells, NK cells
Effective vaccine characteristics
Stimulate B cell and T cell responses, produce long term memory Limited number of boosters Inexpensive, easy to administer, long shelf life
Pyrogens
substances that cause fever
If a TC cell encounters a virally infected TH cell, what will the TC cell do?
The TC cell will induce the TH cell to undergo apoptosis and die.
Type II hypersensitivity
Trigger destruction of cells by complement system or induced lysis Transfusion reaction Hemolytic disease of newborn
Vasodilation will cause a decrease in body temperature. T or F
True
Aggregation
Two arms of antigen bind separate antigens
Herd immunity
Vaccinating large portion of population protects the unvaccinated
Vaccine
Weakened version of microbe/ microbial antigen to cause immunity, protects against future expose
After an infection is cleared, neutrophils will undergo ____, a programmed death that leaves the cell's membrane intact.
apoptosis
Which part of the adaptive immune response is best at recognizing intracellular infections, particularly viral infections?
cell mediated immunity
TCRs (T cell receptors) are capable of bind free antigen as long as the receptor is specific for the antigen. T or F
false
Active immunization
injecting an antigen to stimulate immune system
The ____ responses of the immune system respond quickly to pathogens in a non-specific manner. 'Memory' ____ a feature of these responses.
innate... is not
The binding region of antibodies are constant, while the stem is highly variable. T or F
true
Which of the following hypersensitivity reactions is antibody- independent
type IV
B cells activation is by T dependent antigens
1. BCR binds to antigen, internalizes and degraded into fragments 2. Fragments delivered to MHC (major histocompatibility) class II molecule, inspection by TH cells (antigen presentation) 3. If TCR recognizes fragment, activates B cell with cytokines and B cell replicates and makes many plasma cells 4. If no TH cells recognize peptides, B cell does not respond
Steps of phagocytosis
1. Bacteria binds to the surface of phagocytic cell. antibody or complement can aid binding 2. Phagocyte pseudopods extent and engulf the organism 3. Invagination of phagocyte membrane traps the organism within a phagosome 4. A lysosome fuses and deposits enzymes into the phagosome. Enzyme cleave macromolecules and generate reactive oxygen, destroying the organism
Basic inflammatory response steps
1. Infection via splinter 2. Resident macrophages engulf pathogens and release cytokines 3. Vasoactivate factors and cytokines help deliver additional phagocytes 4. Some cytokines initiate healing as pathogens are destroyed
Complement
20 blood proteins that help prevent blood infection (septicemia) Major goal is to create pores (MACs) in a pathogen membrane
B cell receptors (BCR)
membrane-bound version cell's specific antibody; binding antigen triggers response
Human immunodeficiency virus causes _______
A secondary immunodeficiency
Variable region
Accounts for specificity Antigen-binding site attaches to specific antigen Fit very precise
Pus is composed of ____ and the cellular debris they produce from digested bacterial cells.
neutrophils
What is the outcome of all complement activation cascades?
All pathways ultimately work to form membrane attack complexes (MACs). These complexes form pores (i.e. holes) in the bacterial cell membrane and lead to death of the cell.
How do phagocytic cells determine if a cell is a "self" cell or a "non-self" cell that needs to be engulfed?
All phagocytic cells, macrophages, dendritic cells, and neutrophils, use the CD47 marker to determine if a cell is self or nonself. All of our self cells have this marker, so if a cell without it is detected, it will be phagocytized.
Type I hypersensitivity
Allergic reactions occur in sensitized individuals (prior exposure, IgE produced and binds to receptors) Subsequent exposure results in degranulation by mast cells
Constant region
Allows immune system components to recognize others diverse antibody molecules Fc region at very bottom
Upon activation, B cells differentiate into ______ cells and begin secreting large quantities of ______. These Y-shaped proteins are specific for the antigen that caused the activation of the B cells.
plasma, antibodies
Defensins
positively charged, short amino acid sequences
Neutralization
prevents toxins, viruses from binding
Systemic anaphylaxis
Antigen enters bloodstream, spreads throughout body Basophils and mast cells release inflammatory chemicals Extensive blood vessel dilation, severe drop in blood pressure
Cell-mediated immunity
Antigens residing within a host cell T cells and helper T cells have multiple copies of TCR's Analogous to BCR but does not recognize free antigen Once helper and cytoxic cells activated, proliferated and differentiated it forms effector helper T cells (TH cells) or effector cytotoxic T cells (TC cells)
Physical barriers
Are a tight linage of skin cells prevent bacteria cell entry The mucocilliary elevator helps clear bacteria from the lungs Physical barriers act to prevent infection from occurring
Functional regions of antibody (immunoglobulin)
Arms bind specific antigen Stem (Fc region) is "red flag" to tag antigen, enlist other immune system components to eliminate
Opsonization
B cells produce antibodies, bind to bacteria Phagocyte uses Fc receptors to grab Fc region on antibody Can opsonize with complement proteins
Antigen presenting cells (APCs) are responsible for displaying antigen to T cells. Select all of the following cells that serve as APCs.
B cells, macrophages, dendritic cells
SCID (server combined immunodeficiency
Bone marrow does not produce B or T cells
Which of the following is an example of passive immunization?
Breast milk