Immunohistochemistry in Historical Perspective: Knowing the Past to Understand the Present

Immunohistochemistry is an extraordinary and extensively used technique whereby antibodies are used to detect antigens in cells within a tissue section. It has numerous applications in medicine, particularly in cancer diagnosis. It was Albert Hewett Coons, Hugh J Creech, Norman Jones, and Ernst Berliner who conceptualized and first implemented the procedure of immunofluorescence in 1941. They used fluorescein isothiocyanate (FITC)-labelled antibodies to localize pneumococcal antigens in infected tissues. Since then, with improvement and development of protein conjugation, enzyme labels have been introduced, such as peroxidase and alkaline phosphatase. The history of immunohistochemistry (IHC) combines physiology, immunology, biochemistry, and the work of various Nobel Prize laureates. From von Behring who was awarded de first Nobel Prize in 1901 for his work on serum therapy to the 1984 Nobel Prize for the discovery of monoclonal antibodies by Milstein, Kohler, and Jerne, IHC is a story of cooperation and collaboration which led to the development of this magnificent technique that is used daily in anatomical pathology laboratories worldwide.

The history of the antibody as a tool

Antibodies are essential tools in modern science and medicine, however the history leading to the use of antibodies as tools has not been well-described. The objective of this paper is to analyze the history of immunology from smallpox inoculation to the production of monoclonal antibodies, and to identify turning points in immunological theory leading to the emergence of antibody-tools. In the early 1700's, Western medicine adopted smallpox inoculation from Turkey, along with the idea of acquired immunity. The Germ Theory of disease had to replace spontaneous generation and miasma theory in the 1880's, however, before inoculation could successfully be applied to other diseases. Inquiry into acquired immunity led to the idea of the "antibody" in the 1890's, and the use of antiserum to identify bacteria. Immunostaining was invented in 1942 by repurposing antibody-dye conjugates originally intended as antibiotics. Monoclonal antibody-producing hybridomas were similarly invented in 1975 by repurposing techniques from virology and genetics.

[The rise and fall of pathology techniques]

For the past 150 years the most constant factor in the pathologist's histopathological diagnostic work-up has been haematoxylin staining. This technique, in combination with later additional staining techniques, determined knowledge on a cellular level for a long time. The invention of the transmission electron microscope added an ultrastructural dimension, and for many decennia in the middle of the twentieth century this was an important diagnostic tool. Enzyme histochemistry and morphometry came next, but these techniques never really became important as they were largely overtaken by immunohistochemistry and molecular diagnostics. These, in their turn, will face competition from proteomics and other forms of genomics. It seems likely that the trusty light microscope will lose out to digital microscopy, which is developing rapidly and offers the possibility to make a diagnosis at a distance. Pathology will continue to be a specialty on the move.

[Are there new possibilities in immunomorphology?]

Immunomorphology, including immunohistochemistry and immunocytochemistry, forms a category of well known, reproducible, cost and environment saving immunodiagnostic methods based on immunological specificity. Both the accurate diagnosis and a better knowledge of biological parameters of diseases, especially of malignant tumors, result from the continual development of technologies and applications concerning at least 60 years of history of immunostaining. This review attempts to summarize the most important steps of development of immunomorphology.

The increasing power of immunohistochemistry and immunocytochemistry

Since its introduction in the early 1940s, immunostaining technology has developed in a remarkable way, and the applicability of immunohisto/cytochemical probing methods will unquestionably continue to increase in several directions. Immunofluorescence remains the most powerful and reliable immunohistochemical approach for multicolour staining to evaluate co-localization of two or more antigens in an objective manner. Moreover, the fluorescent colour signals exhibit a relatively consistent relationship to the actual antigen concentration in the test preparation and are hence better suited for quantitative computerized image analysis than light-microscopic observations of immunoenzyme staining. On the other hand, immunoenzyme methods are more economical with regard to reagent consumption and are therefore ideal for the use in semiautomatic staining machines. In addition, the superior morphological correlate provided by the latter methods, makes them more attractive and adequate for most purposes in diagnostic pathology laboratories. However, multicolour immunoenzyme staining provides an easily obtainable and reliable result only when the antigens are known a priori to be separately located, both because of technical problems and because imbalanced colour mixing is difficult to evaluate in the light microscope. All these aspects of immunohistochemistry are briefly reviewed in this historical perspective coloured by the author's own experience.

Immunohistochemistry for light microscopy in safety evaluation of therapeutic agents: an overview

The history of immunohistochemistry started in 1941 when Coons identified pneumococci using a direct fluorescent method. Then followed the indirect method, the addition of horseradish peroxidase, the peroxidase anti-peroxidase technique of 1979 and the use of the Avidin and Biotin complex in the early 1980s. This sequence of events can help one appreciate the differences in these various techniques and their increased sophistication and sensitivity. The technique has been applied in the field of safety evaluation of new pharmaceutical products. Examples of current projects are used to illustrate the scope of the application. The use of an antibody to detect proliferating cell nuclear antigen has, in a pilot study with the popliteal lymph node assay, provided a method of differentiating an irritant response to acetone from an immune response to hydrazine. In hydrazine-treated rats the proliferation is mainly in the follicular region whilst it is mainly sinusoidal in animals treated with acetone. In the guinea-pig maximisation test, initial work with dinitrochlorobenzene suggests that detection of Langerhans cells may aid the differentiation of an irritant from an immune response. The preclinical assessment of antibodies intended for therapeutic use in man requires immunohistochemistry to be used to identify any human tissues which show a cross-reactivity. The major problems are not in the test itself but in obtaining suitable material. Identification of hormones is a useful tool for assessing the effects of releasing factors and has proved useful in aiding tumour identification in routine carcinogenicity studies. In a rare case, detection of prolactin in cell deposits in the lungs of a rat confirmed that this was a metastasis from a pituitary carcinoma. The application of immunohistochemical techniques to preclinical assessment of drugs should always be considered. In particular, it is recommended that appropriate samples should be conserved from routine studies in order to permit these techniques to be performed, if considered appropriate in the light of findings during routine histological examination.

[Immunological research and diagnosis in gastroenterology--a review on occasion of two jubilees]

Norwegian immunological research in gastroenterology is well recognized internationally, and the European Medical Research Council Clinical Network for Gastroenterological Immunology is organized from Oslo. This development can be explained mainly by successful cooperation between clinical gastroenterology and laboratory-based research. A current jubilee in each of these fields may justify this review. It is now well documented that the gut is the largest antibody-producing organ. A unique molecular integration exists between the local B cells and the secretory epithelium to facilitate external transport of dimeric IgA and pentameric IgM. The mucosal immune system is subjected to T-cell regulation and significant local alterations are observed in T- and B-cell populations, and in the macrophage subsets associated with several diseases of the gut. Subsequent functional immune deviation may largely explain mucosal pathology and indicates potential targets for future immunotherapeutic measures. Observations made in the gut mucosa of HIV/AIDS patients have contributed to greater understanding of the complex cellular and molecular interactions involved in mucosal immunity.

From immunohistochemistry to in situ hybridization

The revolutionary evolution in science and technology has made it possible to face adequately three main challenges in modern medicine: old diseases changing, new diseases appearing, diseases remaining unknown. In this paper we review the road travelled by the pathologist in search of a method which is based upon the application to routine work of instruments and techniques which once were available for research only. Application to tissue studies of immunological and molecular biology techniques allows a dynamic interpretation of biological phenomena with special regard to gene regulation and expression. The method implies stepwise investigations, including immunohistochemistry, EM and in situ hybridization, in order to progress from the suggestive features detectable in routinely stained preparations to more characteristic, specific and, finally, pathognomonic features. HE-stained preparations and appropriate immunohistochemical stains enable recognition of phenotypic changes which may reflect genotypic alterations. Thus there is a logical and methodological link between the simple HE and the most powerful techniques so far introduced in pathology: immunohistochemistry and in situ hybridization.