Methods and Techniques Discussion => Immunohistochemistry (IHC) => Topic started by: ihcwor2 on March 12, 2003, 07:50:11 PM

Title: ABC-AP Method (VectorBlack) for Paraffin Sections
Post by: ihcwor2 on March 12, 2003, 07:50:11 PM
ABC-AP Method (VectorBlack) for Paraffin Sections

Solutions and Reagents

A. TBS Buffer (10mM Tris-HCl, 150mM NaCl, pH 7.5):
Tris-HCl (MW 157.60) --------------------- 1.58 g
NaCl (MW 58.44) ---------------------------- 8.77 g
Distilled water -------------------------------- 1000 ml
Mix to dissolve and adjust pH to 7.5

B. AP Buffer (100mM Tris-Cl, 100mM NaCl, 5mM MgCl2, pH 9.5)
Tris-HCl (MW 157.60) --------------------- 15.76 g
NaCl (MW 58.44) ---------------------------- 5.84 g
MgCl2 (MW 203.31 -------------------------- 1.02 g
Distilled water --------------------------------- 900 ml
Mix to dissolve. Adjust pH to 9.5 and then bring total volume to 1 liter.

C.   Antigen Retrieval Solution:
10mM Sodium Citrate Buffer (The most commonly used antigen retrieval reagent):
To prepare 1000 ml,
Sodium citrate ------------- 2.94 g
Distilled water ------------- 1000 ml
Adjust pH to 6.0

Selection of antigen retrieval techniques is crucial for successful staining of paraffin sections. Different antibodies may require different antigen retrieval techniques and need to be tested prior to application of actual projects.

D.   Blocking Solution:
2% Normal Serum and 1% BSA in TBS:
To prepare 100 ml
Normal serum ---------- 2 ml
BSA ----------------------- 1 g
TBS ----------------------- 100 ml
Stir to dissolve.

E.   Primary Antibody:
Dilution of primary antibody is critical for success of staining, so a titration must be performed prior to application of actual projects.

F.   Secondary Antibody:
An appropriate biotinylated secondary antibody should be selected and a titration is needed prior to application of actual projects.

G.   ABC-AP Reagent:
Depending on sensitivity and morphological requirements, there are varieties of ABC-AP kits and reagents can be selected from. The most commonly used one is VECTASTAIN ABC-AP Kit from Vector Laboratories.      

H.   VectorBlack Reagent


1.   Deparaffinize sections in xylene for 3x5min.
2.   Hydrate with 100% ethanol for 2x5min.
3.   Hydrate with 95% ethanol for 2x5min.
4.   Rinse in distilled water.

5.   Antigen Retrieval: (Select an appropriate antigen retrieval technique and it depends on antibodies used).
6.   Rinse sections in TBS for 1x5min.

7.   Blocking: incubate sections with blocking solution for 30 minutes to block non-specific binding of secondary immunoglobulin.
8.   Rinse in TBS for 1x2min.                                                                        

9.   Primary antibody: incubate sections with primary antibody diluted in blocking solution for 1 hour at room temperature (A titer must be performed prior to actual projects)
10.   Rinse in TBS 3x5 min.

11.   Secondary antibody: incubate sections with biotinylated secondary antibody in TBS for 30 minutes at room temperature.
12.   Rinse in TBS for 3x5min.

13.   ABC-AP: incubate sections with ABC-AP complex or AP-streptavidin reagent in TBS for 30 minutes at room temperature.
14.   Rinse in TBS for 3x5min.

15.   VectorBlack: incubate sections with VectorBlack solution containing 1mM Levamisole for 20-30 minutes
16.   Rinse in distilled water 2x5min.

17.   Counterstain with nuclear fast red if desire.
18.   Rinse in distilled water 2x5min.
19.   Dehydrate through 95% ethanol for 5min, 100% ethanol for 2x5min.
20.   Clear in xylene for 2x5min.

21.   Coverslip with mounting medium.


1.   Positive staining ----------------------- black
2.   Nuclei ------------------------------------- red