The road from cytotoxins to immunohistochemistry.

This review article traces the immunohistochemistry ancestry of cytotoxins as antibodies. The immunohistochemistry success, as a diagnostic and research test, stood on the shoulders of negative and positive experimentation results with cytotoxins from the first half of the twentieth century. This is when experimental immunologists came with the understanding of the need for both antigen and antibody purification to achieve specificity of the immunological reaction. Simultaneously, protocols were developed, which involved injecting antigenic material into experimental animals. During this time, reliable methods for evaluation of antiserum strength or titer were established. The evolution of antigen preparation for immunofluorescence is presented here as one of the transitional steps to modern immunohistochemistry. This work paved the way for the development of the monoclonal and polyclonal antibodies methodology. The article is written from the author's perspective as an experimental immunologist and a hands-on participant during many steps of development in modern morphological laboratory diagnostics. Knowledge of the roots of immunohistochemistry is useful for laboratory professionals in appreciation of predecessors' contributions. Familiarity with history of experimental immunology would be beneficial for understanding the methodological principles of their current work as well as future development prospects.