Upload
kovit
View
52
Download
1
Tags:
Embed Size (px)
DESCRIPTION
Applications of Immune Responses. Chapter 19. Principles of Immunization. Naturally acquired immunity is acquisition of adaptive immunity through natural events Immunization mimics these events by inducing artificially acquired immunity Natural or artificial immunity can be divided into - PowerPoint PPT Presentation
Citation preview
Naturally acquired immunity is acquisition of adaptive immunity through natural events
Immunization mimics these events by inducing artificially acquired immunity
Natural or artificial immunity can be divided into› Active immunity › Passive immunity
Active immunity› Results from
immune response upon exposure to an antigen
› Active immunity can develop naturally Following illness
› Or artificially After
immunization
Passive Immunity› Occurs naturally during
pregnancy IgG from mother crosses
placenta Infers protection to the baby
› Occurs naturally as result of breast feeding IgA antibodies in breast milk
given to child› Artificial passive immunity
involves transfer of antibodies produced by another person or animal Can be used to prevent
disease before or after likely exposure
Attenuated vaccines› Weakened form of pathogen
Generally unable to cause disease
› Strain replicates in vaccine recipient Causes infection with undetectable or mild
symptoms Results in long lasting immunity
Attenuated vaccines› Advantages
Single dose usually sufficient to induce long-lasting immunity Due to multiplication of
microbe in body Continued stimulation
of immune system Vaccine has added
potential for being spread “Disease” after
immunization could be spread to un-immunized individuals inadvertently
› Disadvantages Have potential to
cause disease in immunocompromised individuals
Pregnant women should also avoid immunization with attenuated vaccine
› Attenuated vaccines in use include Sabin polio vaccine MMR Yellow fever
Inactivated vaccines› Unable to replicate in vaccinated individual› Retains immunogenicity of infectious agent
Immunogenic not pathogenic
› Inactivated vaccines fall into two categories Whole agents
Contain killed organisms of inactivated virus Does not change epitopes Cholera, plague, influenza and Salk polio are whole
agents Fragments
Portions of organisms or agents including toxins, proteins and cell wall components
Terms› Seronegative
Person not yet exposed to antigen and has no specific antibodies
› Seropositive Person with exposure and actively producing antibody
› Titer Concentration of antibody in serum---Indicates
previous exposure
Obtaining antibody› Serum is fluid portion of blood with no
clotting factors› Plasma is fluid portion with clotting factors› Laboratory animals are used to produce
known antibodies Animal is immunized with antigen and
produces specific antibodies Antibodies are retrieved by harvesting
animal’s serum
Quantifying antigen-antibody reactions› Concentrations of antibody usually determined
through dilution› Antigen added to dilution
Titer is taken from last dilution to give detectable reaction
Precipitation reactions› Antibodies binding to
soluble antigen form insoluble complexes Complexes precipitate
out of solution
› Complete aggregate formation occurs at certain concentrations
› To achieve concentrations, place separate antigen and antibody suspensions side by side
› Diffuse together to create zone of optimal proportion
Immunodiffusion tests› Most widely known is Ouchterlony› Antigen and antibody placed in
separate wells cut in gel Solutions diffuse and meet between the
wells Result in line of precipitation at zone of optimal
proportion
Immunodiffusion tests› Radial immunodiffusion test is quantitative› Antibody is added to liquid agar that is
allowed to harden Creates a uniform antibody concentration
› Antigen added to wells cut in gel Diffusion outward forms concentration gradient Ring forms at antigen-antibody precipitation
› Standards can be used to construct standard curve to establish concentration
Immunoelectrophoresis› Proteins separated using gel
electrophoresis› Antibodies are placed in
wells and allowed to diffuse towards separated proteins
› Line of precipitation forms at antibody-protein recognition
› Used to determine patient antibody levels High levels of certain antibody
classes can indicate disease
Agglutination reactions› Large insoluble particles are involved› Obvious aggregations are formed
Makes them easier to see› Direct agglutination
Specific antibody mixed with insoluble antigen Readily visible clumping indication of positive result
› Indirect agglutination Amplifies aggregation formation
Antibody attached to latex bead Agglutination of these beads much easier to see
Detectable markers can be attached to specific antibodies› Marked antibodies used to detect presence of given
antigen Tests include
› Fluorescent Antibody (FA) test › Enzyme-Linked Immunosorbant Assay (ELISA)› Western blotting› Fluorescence Activates Cell Sorter (FACS)
Fluorescent antibody test› Relies on fluorescent
microscopy to locate labeled antibodies fixed to a microscope slide
› Fluorescent polarized immunoassay uses beam of polarized light to rate spin of labeled antibodies Works under principle
that bound antibodies are heavier then unbound and will spin more slowly
Enzyme-Linked Immunosorbant Assay (ELISA)› Employs antibody that
has been labeled with detectable enzyme Commonly horseradish
peroxidase› Labels antibody bonds to
antigen Binding can be direct or
indirect› Antigen location is
determined using colormetric assay
Enzyme-Linked Immunosorbant Assay› Direct ELISA
Looks for specific antigen Specimen placed in wells of
microtiter plate Wells treated with
antibody for antigen
› Indirect ELISA Looks for antibody in
patient serum Human IgG Wells of plate treated with
known antigen
Western blotting› Technique used to
detect antigenic proteins
› Proteins are separated by size before reacting with antibody Proteins separated by
special gel electrophoresis SDS PAGE
› Makes it possible to establish which proteins are recognized by antibodies
Fluorescence Activated Cell Sorter (FACS)› Special version of flow cytometry counts
cells labeled with fluorescent antibodies› Used to count subsets of T cells
CD4 and CD8 cells especially Antibodies are attached to the CD4 and CD8
markers Cells with fluorescently labeled markers are counted