Immunohistochemistry

The immunohistochemistry laboratory in our department is dedicated to the this particular service. Immunohistochemistry is a branch of science that uses specific antibodies to locate antigenic sites in tissue sections. When used as a panel of assorted antibodies, it serves as a very useful and extremely powerful tool in diagnostic pathology. There are numerous protocols in use. Generally, immunohistochemical techniques are grouped as direct or indirect methods using enzyme or fluorescent conjugates to reveal the antigenic sites in tissue sections.

Peroxidase is an example of an enzyme conjugate which reveals the localisation of antibody-bound antigenic sites by means of a coloured reaction. DAB(3,3-diaminobenzidine) is the chromogenic substrate for peroxidase, which stains antigen-antibody sites brown.

	The photomicrograph shows a group of 'groundglass' hepatocytes suggestive of hepatitis B infection.
The brown coloration within the 'groundglass' hepatocytes is brought about by peroxidase induced conversion of DAB which confirms the presence of hepatitis B antigen (HBsAg) within the 'groundglass' hepatocytes.