IMMUNOHISTOCHEMISTRY_Bruce Flashcards
are now routinely used for the identification of specific or highly selective cellular epitopes or antigens in frozen or paraffin-embedded tissues.
Immunohistochemical techniques
can also be used to detect organisms in cytologic preparations such as fluids, sputum samples, and fine needle aspirates.
Immunocytochemistry
Antibodies belong to the class of serum proteins known as…
immunoglobulins
is the most commonly used antibody for immunocytochemistry
IgG
is the structural part of the antigen that reacts with an antibody.
epitope
combines anatomical, immunological and biochemical techniques to identify discrete tissue components by the interaction of target antigens with specific antibodies tagged with a visible label.
Immunohistochemistry (IHC)
makes it possible to visualize the distribution and localization of specific cellular components within cells and in the proper tissue context.
IHC
While there are multiple approaches and permutations in IHC methodology, all of the steps involved are separated into two groups:
sample preparation and labeling.
is used for disease diagnosis, drug development and biological research.
IHC
Using___________, physicians use IHC to diagnose a cancer as_____, determine the______ of a tumor, and identify the cell type and origin of a______ to find the site of the primary tumor.
specific tumor markers
benign or malignant
stage and grade
metastasis
IHC is also used in _______to test drug efficacy by detecting either the activity or the up- or down-regulation of disease targets.
drug development
Samples can be viewed by either____ or _____ microscopy, and advances in the last 15 years have improved the ability to capture images, quantitate mult-Oparametric IHC data and increase the collection of that data through high content screening.
light or fluorescence
are produced by immunizing an animal with a purified specific molecule (immunogen) that contains the antigen of interest, and collecting immunoglobulin-rich serum after the animal has produced humoral antibody against the antigen.
Polyclonal antibodies
The most frequently used animal for the production of polyclonal antibodies is the
rabbit, followed by goat, pig, sheep, horse, guinea pig and others.
Some of the_______ antibodies may cross-react with other molecules and cause nonspecific staining, requiring their purification by absorption with the appropriate antigen, or antibody dilution to eliminate the unwanted reaction.
polyclonal
are the products of an individual clone of plasma cells.
Monoclonal antibodies
techniques have been developed to produce monoclonal antibodies that do not cross-react with other molecules.
Hybridoma and cloning
Antibodies from a given clone are immunochemically identical and react with a specific epitope on the antigen against which they are raised.
Monoclonal
are currently used almost exclusively for the production of monoclonal antibodies.
Mice
In certain instances, the tissue must be prepared as a______ section and fixed for a few seconds in______ or _____, to preserve immunological activity and prevent destruction of some of the labile antigenic sites.
However,_______ and______ techniques may also be done on formaldehyde-fixed and paraffin embedded sections.
cryostat
absolute methanol or acetone
immunofluorescence
immuno-peroxidase
Many masked antigens can now be retrieved in routinely processed tissue by
(1) proteolytic enzyme digestion
(2) microwave antigen retrieval
(3) microwave and trypsin antigen retrieval
(4) pressure cooker antigen retrieval
Proteolytic Enzyme Digestion
Formalin fixed paraffin sections are usually pre-treated with_____ to break down formalin cross-linking, unmask and allow certain antigenic sites to be exposed.
proteolytic enzymes
_________ is especially useful for demonstrating heavy chain immunoglobulins, complement and specific antigens (such as cytokeratin) in formalin-fixed paraffin-embedded biopsies.
The most common enzymes used are____ and _____
Proteolytic enzyme digestion
trypsin and protease
Proteolytic Enzyme Digestion
Before pretreatments are employed, the sections are______, taken to alcohol and, in the case of peroxidase labeling, treated with 0.5% methanol in hydrogen peroxide for 10 to 15 minutes to destroy endogenous peroxidase activity.
deparaffinized
Proteolytic Enzyme Digestion
The trypsin method uses _____in _____in distilled water, adjusted to pH 7.8 with sodium hydroxide, and preheated at 37°C.
The slides are also preheated at 37°C in distilled water before placing in freshly prepared trypsin solution. After a predetermined period of time, the slide is transferred to cold running water to terminate enzyme digestion.
0.1% trypsin
0.1 % calcium chloride
Proteolytic Enzyme Digestion
The protease method uses______ in distilled water, adjusted to pH 7.8 with sodium hydroxide.
The section is preheated at 37°C in distilled water and placed in protease solution for a shorter period of time due to its faster rate of enzyme digestion.
0.05 to 0.1% protease
Proteolytic Enzyme Digestion
Pre-treatment of Tissue Sections
Antigenic determinants masked by formalin-fixation and paraffin-embedding often may be exposed by…
epitope unmasking
enzymatic digestion or saponin
etc.
Proteolytic Enzyme Digestion
Do not use this pretreatment with frozen sections or cultured cells that are not paraffin-embedded.
Unmasking
Proteolytic Enzyme Digestion
: Incubate sections with normal serum block - species same as secondary antibody, for 30 minutes to block non-specific binding of immunoglobulin.
Note: This protocol uses avidin-biotin detection system. Avidin-biotin block may be needed based on tissue type. Normal serum block should be used prior to avidin-biotin block.
Serum Blocking
Proteolytic Enzyme Digestion
Primary Antibody
: Incubate sections with primary antibody at appropriate dilution in primary antibody dilution buffer for__________ or ________
1 hour at room temperature
overnight at 4 °C
Proteolytic Enzyme Digestion
Peroxidase Blocking
: Incubate sections in peroxidase blocking solution for ________
10 minutes at room temperature.
Proteolytic Enzyme Digestion
Secondary Antibody: Incubate sections with biotinylated secondary antibody at appropriate dilution in PBS for_____
30 minutes at room temperature.
a simple laboratory technique that has become an essential part of many immunohistochemistry and in situ hybridization procedures, is a pretreatment method used to improve staining results.
Heat-induced epitope retrieval (HIER)
….., coupled with specific buffered solutions, is utilized to recover antigen reactivity in formalin fixed paraffin embedded tissue.
It reverses the formaldehyde mediated chemical modifications of the antigen
Heat
Heat reverses the formaldehyde mediated chemical modifications of the antigen through either of the following processes.
First and foremost, thermal energy breaks the____ that bind surrounding proteins or peptides to the antigen which lead to the “opening” or “unmasking” the epitope.
And, second, thermal energy removes______ from the sites of cross-links since several HIER buffers, such as EDTA and citrate, act as calcium chelators.
crosslinks
bound calcium ions
HIER heating sources include the
microwave
vegetable steamer
pressure cooker
water bath
T or F
the higher the temperature of the HIER solutions, the more effective the recovery of the epitope is.
True