Module 1 Flashcards
Immunology
Definition
The study of the immune system
Immune system
must recognize your body as “self” and the invader as foreign
Many systems work together to protect the body
Good response vs bad response
How we can manipulate or help the body (vaccines)
First line of defense in the immune system
unbroken skin and mucosal membrane secretions
Ways to classify immunity
natural vs acquired
humoral vs cellular
passive vs active
Natural immunity
Your inborn resistance (phagocytes, complement, an acute inflammatory response)
Complement
inert substance in the blood capable of binding certain antibodies helping to destroy the foreign substance through lysis
When does CRP elevate
before disease. good warning sign!
Acquired or Adaptive Immunity
Allows the body to recognize, remember and respond to a stimulus (antigen)
Whenever T-cell and B-cells are activated, some become memory cels
Humoral Immunity
Acquired if the antibodies are formed by the host or received from another source
Mode of action is antibodies in the serum
Cells: B-lymphs
Mechanism: antibody-mediated
Purpose: primary defense against bacterial infection
Cellular Immunity
Delayed hypersensitivity
Moderated by the link between T-lymphs and phagocytes: T-cells recognize when an antigen is present on a phagocyte
Mode of action: cell-to-cell contact or soluble products secreted by cells
Cell type: T-lymphs
Mechanism: cell-mediated
Purpose: Defense against viral and fungal infections, tumor antigens and graft rejections
Passive Immunity
May be naturally occurring or acquired artificially
Natural: passes across the placenta during pregnancy but decreases after birth
Artificial: when antibody-containing serum is administered- Rhogam or hepatitis immune globulin
Not permanent - titers drop over time
Active immunity
Immune response that is triggered by infection (natural active immunity). Stronger than artificial immunity
Immune response that is triggered by vaccination (artificial active immunity). Intended to be permanent or may require a booster
Vaccines
Suspensions of antigenic material of animal or plant origin
Should stimulate antibody production without clinical symptoms of disease in a health (immunocompetent) person
Should cause permanent memory
May be composed of living suspensions of weak or attenuated cells or viruses
May contain only a portion of the infectious agent
Hypersensitivity Reactions
Bad condition of the body tissues caused by antigenic stimulation
Two classifications: delayed hypersensitivity reaction or immediate hypersensitivity reaction
Delayed Hypersensitivity Reaction
Often used synonymously with cell-mediated immunity
Refers to the slow appearance of a secondary response in the skin
Immediate Hypersensitivity
Mediated by IgE immunoglobulins due to allergens
Self-tolerance
Exists when the immune cells and other body cells exist peacefully together
What government agency is primarily responsible for safeguards and regulations to ensure a safe and healthful workplace through the United States
Occupational Safety and Health Administration (OHSA)
Standard Precautions
Treating all specimens as if they are infectious
Assuming that every direct contact with a body fluid in infectious
The CDC’s Bloodborne Pathogen Requirement mandates
Education and training of all healthcare workers in Standard Precautions
The single most common source of human immunodeficiency virus in the occupational setting is
Blood
When using gloves for phlebotomy or blood specimen processing, laboratory staff should
wash hands after removing gloves
Gloves for medical use may be
sterile or nonsterile
Diluted bleach for disinfecting work surfaces, equipment, and spills should be poepared daily by preparing a __ dilution of household bleach. This dilution requires ___ mL of bleach diluted to 100 mL with H2O
1:10
10
Infectious waste must be discarded into containers with what features
Markled with biohazard
has standard biohazard symbol
orange, orange and black, or red
Clinical laboratory personnel need to have demonstratable immuity to
Rubella and Hepatitis B
What is an antigen
Any substance capable of stimulating antibody formation and has the ability to bind to that antibody or t-cell receptor, but may not be able to cause an initial immune response
Antigen examples
viruses
bacteria
fungus
parasite
portion of a product- capsule, endotoxic, cell wall
tissue or cells from another individual- organ/bone marrow transplant or blood transfusion
Antigen vs. immunogen
All immunogens are antigens, but not all antigens are immunogens
Immunogens trigger an adaptive immune response by inducing the formation of antibodies or sensitized T-cells
Immunogens react with specific antibodies or sensitized T-cells
Antigenic Determinants
Epitope
Epitope is location that determines antigen
Chemical nature of antigens
Usually proteins or large polysaccharides
Rarely lipids
Proteins are excellent antigens because of the high molecular weight and structural complexity
Lipids are poor antigens unless they are linked to a protein or large polysaccharides
Physical nature of antigens
Foreignness- must be recognized as non-self
Degradability- repidly destroyed becayse they are foreign; must be sufficient in number to elicit an immune response
Molecular weight- the higher the molecular weight; the better the molecule will function as an antigen
Structural stability- if unstable (lipid) is will be a poor antigen
Complexity- the more complex; the more effective it will be
Antibodies
speficifc glycoproteins
usually referred to as immunoglobulins
can be found in blood plasma and many body fluids such as tears, saliva and colostrum
Antibody primary function
to combine with an antigen - this may be sufficient to neutralize bacterial toxins or some viruses
May combine with complement to dispose of larger antigens like bacteria
Antibody structure
All have a common basic polypeptide structure that has a 3-dimensional configuration
Is a protein
4-chain structure based on pairs of heavy and light chains.
Area that holds the antigen is called the variable region or Fab region (fragment antibody)
The stem lets the Ab bind to complement or macrophages. It is called the constant region or Fc region (fragment constant)
Immunoglobulins concentration from greatest to least
IgG, IgA, IgM, IgE, and IgD
G A M E D
IgG
70-75%
Diffuses into extravascular spaces where it neutralizes toxins or binds to microorganisms
Can cross the placenta
When IgG complexes are formed, complement can be activated
IgG1, IgG2, IgG3, and IgG4
Monomer
IgA
15-20%
predominant in secretions such as tears, saliva, colostrum, milk and intestinal secretions
alpha1 and alpha 2 subclasses.
Secretory IgA protects against microorganisms
a monomer (1 Y) in plasma
a dimer (2 Y) when secreted
J chain
joins antibody chains together
IgM
10%
confirmed to the intravascular pool since its so large
produced first in an immune response and confined to blood
has five pairs of heavy chains; therefore, IgM is a pentamer (has 5 Y’s)
IgE
trace plasma found in blood
less than 1-2%
mediates some types of hypersensitivity (allergic reactions and anaphylaxis)
generally responsible for an individual’s immunity to invading parasites
monomer
binds strongly to a receptor on mast cells and basophils and mediates the release of histamines and heparin from these cells
IgD
Less than 1%
found in very low concentrations in plasma
Primarily a celll membrane immunoglobulin found on the surface of B-lymphocytes in association with IgM
IgD is a monomer
Immunoglobulin monomers
IgG
IgE
IgD
IgA in plasma
Immunoglobulin dimers
Secretory IgA
Immunoglobulin pentamer
IgM
Antibody synthesis
Production of antibodies is induced when the host’s immune system comes into contact with a foreign antigenic substance and reacts to the substance
Immune response can be cell-mediated or humoral (antibody)
Primary antibody response
lag
log
plateau
decline
IgM and IgG primarily form
lag
no antibody is detectable
log
antibody titer rises exponentially
plateau
the antibody titer stabilizes
decline
the antibody used and decreases- catabolized
Secondary Response
subsequent exposure ti the same antigenic stimulus produces an antibody response that differs from primary response by:
shorter lag, longer plateau and a more gradual decline
primarily IgG
antibody levels attain a higher titer
referred to as anamnestic response or IgG response
Antibody specificity and cross-reactivity
antigen-antibody reactions can show a high level of specificity
if molecules are genetically similar, it can cause an immune response, even if you weren’t allergic to it. Ie heterophile antibodies produced in mononucleosis cross-react with Reagin antibodies produced in syphilis
