Cytopathology and Antibody Diagnostics Flashcards
What does a cytopathologist look at?
Cells.
What is the procedure for preparing a cell?
Take a cell sample.
Smear on a slide.
Stain the cells.
What can a cytopathologist not comment on?
The overall architecture of the tissue.
How can cytopathologists access relatively inaccessible tissues without performing a highly invasive technique such as surgery?
They can use a fine needle aspirate.
This is when they use a fine needle to aspirate (suck out) the cells which can then be analyzed for a smear.
Circulating double-stranded DNA can be a sign of some diseases. Give some examples.
Systemic lupus erythematosus (SLE)
Sjoergren’s syndrome
Rheumatoid arthritis
What can we use to detect circulating double-stranded DNA?
Ant-double-stranded DNA antibodies.
What are antibody conjugations?
They are attached molecules that bind to the Fc region of the antibody.
What are can we conjugate to an antibody?
Enzymes
Fluorescent probes.
Magnetic beads.
Drugs.
How can we use conjugated enzymes to stain target cells?
If we bind the antibody to the antigen and then add a colourless substrate, the enzyme can turn that colourless substrate into a product wherever the antibodies bound. This will then stain the tissues.
How else (apart from enzymes) can we conjugate something to an antibody to produce a visual reaction?
Fluorescent probes.
What are the advantages of using fluorescent probes over enzymes?
They give a more rapid response as the colour is already present in the probe, we don’t have to wait for the enzyme-catalysed reaction.
We can also use multiplexing which is when we use several antibodies with different fluorophores attached, important for when we want to get as much information out of a sample as we can (usually for a sample that is very small in volume and took a lot of effort to collect).
How can magnetic beads be used in antibody assisted diagnostics?
With the use of a magnet, we can purify target cells. The antibody will be specific to that target cell and the magnet beads will cause the cells to move towards the magnet. This is a very quick process.
How can drugs be used in combination with antibodies?
Drugs such as Kadcyla, an anti HER2 antibody, can deliver drugs specifically to tumour cells (HER2 is overexpressed in many breast cancers).
What makes antibodies powerful diagnostic tools?
The unique specificity of antibodies in combination with their relatively easy manufacturing process makes them very powerful diagnostic tools.
What are the two ways an antibody can detect an antibody?
It can either be direct detection where the antibody binds directly to the antigen or an indirect detection where the antibody bind to another, unlabelled antibody that binds to the antigen (it could also be an antibody binding to an antibody binding to antibody binding to an antigen).
What are the three main uses of antibody diagnostics?
Blood group serologies
Immunoassays
Immunodiagnostics
What is ELISA?
Enzyme-linked immunosorbent assay
Clinical samples are taken (adheres to a plastic plate)
They are probed with a specific antibody raised against the molecule of interest
The enzyme conjugation generates a coloured product
It can be referenced to standard curve to determine the precise concentration of the molecules in the sample.
Describe flow cytometry.
Cells are labelled with differently conjugated antibodies.
It is run as a stream of single cells through a laser beam.
The colour of light emitted and the forward or side scatter of the laser beam denotes the identity of the cell surface molecules expressed and the size and granularity of the cells.
What can be used to detect pan (all) T cell antigens?
Anti-CD3+
What can be used to detect T helper cells?
Anti CD4+
What can be used to detect cytotoxic T cells?
Anti-CD8+
What can be used to detect B cells?
Anti-CD19+
What can be used to detect Natural Killer (NK) cells?
Anti-CD56+
