Immunohistochemical detection of serum autoantibodies--a new technique using routine formalin fixed paraffin sections.

Detection of autoantibodies in serum is important in the diagnosis of primary immune mediated diseases. Tests of these antibodies are conventionally done by indirect immunoflourescence (IIF) on frozen sections of fresh target tissues from the murine species. More recently enzyme-linked immunoassays and IIF on cultured human epithelial cells or on fresh frozen sections of murine tissues coated onto wells or glass slides are also being used. But these tests are more expensive and generally not easily available to laboratories in developing countries. Obtaining small animals for preparing frozen sections of fresh tissue is also getting to be increasingly difficult. A simple; new and inexpensive technique was developed to perform IIF on routine paraffin sections of human tissues following antigen unmasking. This, technique offers qualitatively good, consistent, species specific and dependable results with several advantages over the conventional IIF on animal tissue frozen sections, particularly in a sausage block made from different types of tissues. Immunoperoxidase stain for autoantibodies can also be easily performed with the advantages of permanent preservation and clearer evaluation in light microscopy. Most importantly the technique is easily affordable and practicable in all histopathology laboratories.