Clinical applications of the enzyme labeled antibody method. Immunoperoxidase methods in diagnostic histopathology.

Histological criteria for the definition of disease entities have largely been established with light microscopy of conventionally stained and routinely processed tissue sections. More or less specific histochemical staining procedures and more recently enzyme-histochemical and quantitative histo- and cytochemical techniques in some cases provided additional criteria. In the last decade, however, the introduction of immunofluorescence and more recently the different immunoperoxidase methods have significantly influenced the scope of contemporary histopathology. Especially, the possibility to use immunoperoxidase methods on routinely processed tissue specimens has offered new dimensions in diagnostic pathology. These methods proved of particular importance for: 1) The development of new criteria for diagnosis, prognosis and treatment (e.g. immunological classification of lymphoma; plasmacell typing in intestinal inflammatory conditions; human chorionic gonadotropin and alpha-fetoprotein in germ cell tumors of the testis). 2) The possibility of etiological diagnosis (e.g. the recognition of hepatitis B viral antigens in liver biopsy specimens; histological typing of causative micro-organisms in inflammatory conditions). 3) The recognition of disease entities that were hitherto unrecognized (e.g. hyperplasia of parafolicular C-cells in the thyroid in multiple endocrine neoplasia syndromes; gastric G-cell hyperplasia as a variant of Zollinger-Ellisons syndrome). 4) Functional analysis of tissue components (e.g. hormone content of pituitary and pancreatic adenomas; cytoplasmic differentiation produces in "undifferentiated" tumors). It can be expected that immunoenzymehistochemistry will soon play a major role in routine diagnostic histopathology.