Module 5 Flashcards
tools used in order to understand and help fight infections
-ELISA
-Flow Cytometry
-Monoclonal Antidies
ELISA
Enzyme-linked immunosorbent assay (ELISA) is a fundamental tool of clinical immunology based on the principle of antigen-antibody interaction
Flow Cytometry
method of detecting and quantifying different cell types in a mixed cell suspension.
analyzes cell suspensions and translates this information into datasets
Monoclonal Antibodies
developed by Georges Kohler and Cesar Milstein in 1975
-antibodies that are produced by a single clone of a B cell that are specific for a single epitope
ELISA can be modified to detect:
pepties, proteins, antibodies, hormones and other molecules
why is ELISA highly specific?
based on principle of antibody-antigen interaction an the antibody binding site is very specific to one antigen
1st step of indirect ELISA
bottom of wells are coated with an antigen that is specifically recognized by the antibody you wish to measure (primary antibody)
What happens between steps in indirect ELISA
wells are washed to remove any excess antigen not attached to the bottom of the well
step 2 of indirect ELISA
sample containing antibody to be measured is added to well. Primary antibodies, if present, will bind to the antigens attached to the bottom of the well
Step 3 of indirect ELISA
an enzyme-conjuated secondary antibody is added to the well. THis secondary antibody will bind to the Fc portion of the primary antibodies already presnt in the well. The secondary antibodie used specifically recognizes antibodies from a particular animal
step 4 indirect ELISA
the substarte of the enzyme attached to teh secondary antibody is added to the well. The reaction of the substrate (a chromogen) and the enzyme produces a coloured product which can be measured by absorbance
chromogen
a substance that can be readily converted into a dye or other coloured compound
What does ELISA measure
- a coloured reaction product by absorbance with the help of a machine
Indirect ELISA
detects or quantifies antibody. Ex, to determine the presence of serum antibodies against HIV
Enzyme-conjugated secondary antibody
a secondary antibody specifically binds to the primary antibody. (has enzyme attached to it)
how can flow cytometry be used to diagnose AIDS/HIV
used to identify and count these specific T-cells in a blood sample
How does Flow cytometry work
-single file stream of cells passed through laser light
-scattering of laser light unique to each cell type
-measuring FSC allows for discrimination of cells by size
-FSC intesnsity proportional to diameter of cell
-SSC provides infro about internal complexity of cell
-also used to det. proportion of cells expressing a particular antigen via stain
FSC and SSC measured in conjunction
allow for detection of specific heterogenous population
What does flow Cytometry measure
-physical properties of a cell
-detecg specific antigens on or inside a cell
what is readily determined via flow cytometry
-total number of cells in suspension
-number of cells of a particular type in the suspension
-overall composition of suspention
what is flow cytometry used to determine
complete blood counts
when would one use flow cytommetry
used to count and analyze size, shape and properties of individual cells within a heterogenous population of cells
Aneuploidy
the presence of an abnormal number of chromosomes
Main diagnostic test of flow cytometry used to diagnose cancer
detecting DNA sneuploidy, analyzing cell cycles, and th e immunophenotypical characterization
what substances is flow cytometry used on
mainly blood, also bodily fluids or emulsified tissues
How do monoclonal antibodies work?
monoclonal antibodies are produced in the lab by hybridomas, imortal cells that produce unlimited quantities of one identical antibody
Hybridomas
hybridomas are the result of fusion bw plasma cell and cancerous cell (share properties of both)
Properties of Myeloma cell
immortal growth that divides indefinitely
properties of plasma cell
produce specific antibodies against one antigen
properties of hybridoma cell
a perpetual source of antibodies against one antigen
what do monoclonal antibodies measure?
-not a specific technique of measurement
-clinical application include immunotoxins and radiolabelled antibodies
Immunotoxins
consist of tumour specific monoclonal antibody attached to deadly toxin
long term objective of immunotoxins
to target and eliminate tumour cells and treat cancer
Radioleballed antibodies
Monoclonal antibodies tagged with a radioactive isotope can be used to diagnose tumour earlier than other methods. Radiolabelled antibodies can bind to antigens on a tumour thereby allowing the percise location of a tumour within the body to be visualized
what is a vaccine
biological preparation providing articfical active immunity to particular disease-causing agent
types of vaccines
- Live attenuated vaccine
- Kill-inactivated vaccine
- Toxoid Vaccine
- Subunit vaccine
Characteristics of live attenuated vaccine
-contains modified strain of disease-causing agent which has lost pathogenic ability but retains its capacity to replicate within host
examples of live attenuated vaccine
smallpox
-oral polliovirus
-measles
advantages of live attenuated vaccine
-provides prolonged exposure to the disease-causing agent, and its suitable to generate cell mediated immunity
disadvantages of live-attenuated vaccine
-potential to revert to virulent form
-requires specific storage and transport conditions
characteristics of killed-inactivated vaccine
-contains strain of the disease-causing agent that has been inactivated by heat, chemicals or radiation
-ability to generate an immune response but is unable to replicate
examples of killed-inactivated vaccine
-rabies
-Flu (influenza) vaccine
advantages of killed-inactivated vaccine
-safer as i cannot mutate to virulent form
-easy to store and transport
disadvantages of killed-inactivated vaccine
-generally requries multiple booster doses to maintain immunity
-must be administered by injection
characteristics of toxoid vaccines
-contains inactivated toxin which is a product from the pathogen that is causing the disease
examples of toxoid vaccines
-tetanus
-diptheria
advantages of toxoid vaccine
-safe as it is not a living organism that can divide, spread and/or revert
-stable as they are less susceptible to changes in temperature, humidity and light
disadvantage toxoid vaccicne
-may require several doses and usually need an adjuvant (substance enhancing bodys immune response to antigen)
characteristics of subunit vaccine
contains only small part or fragment of disease causing agent
examples of subunit vaccine
-hepatitis B
advantages of subunit vaccine
-safest type of vaccine, can be used on everyone, including immunocompromised, pregnent and elderly