Second point: animal tumor models and their relevance to human tumor immunology.

Under the title given to these exchanges, we have been required to explore immunological analogies between clinical cancer and the animal models available for investigation. My article focused attention on a class of model (naturally arising tumors) that has been relatively neglected for reasons that have nothing to do with scientific strategy. Yet it is this class of tumor for which the analogy most relevant to our underlying concern is most solidly sustained: their unresponsiveness to preventive or therapeutic immunological measures. I am dismayed that Herberman is not inclined to embrace this cogent analogy but seems more concerned with vindicating the use of those classes of model by which, as is now widely acknowledged, we have been so long misled. The question arises as to why any discussion of the clinical prospects of applied tumor immunology should polarize the discussants in the way exploited by editorial encouragement of these "ping-pong" contributions. There can be few paramedical topics that are so subject to bipartite discussion--between believers, defenders, and optimists on one side, and critics or skeptics on the other. My conviction is that this proclivity for confrontation betrays a conflict between emotional disposition and scientific judgment. The concept of natural or induced host control of malignant disease has persisted for over 180 years (11) and has survived the many transformations that have occurred over that time of the experimental facilities available for its examination.(ABSTRACT TRUNCATED AT 250 WORDS)