Microwaves in diagnostic immunohistochemistry

Immunostaining has been shown to be clearly superior in tissues immersed in normal saline and fixed by primary exposure to microwaves (MWs) as compared to that fixed routinely in 10% buffered formalin. MWs have also been applied to dry cryostat sections and to accelerate antibody-antigen reactions in the staining of labile lymphocyte membrane antigens in such sections. MWs can also be employed to accelerate immunostaining in paraffin sections, producing significant reduction in all stages of the staining procedure. The more recent application of MWs for epitope retrieval has made an important step towards not only producing better immunostaining of routinely fixed tissues but also towards the standardisation of the immunostaining process. MW-irradiation of paraffin-embedded sections in 10 mMol citrate buffer solution produced, with few exceptions, increased intensity and extent of immunostaining of a wide variety of tissue antigens. Moreover, proteolytic enzyme digestion was not necessary in most instances and some primary antibodies could be used at higher working dilutions.