Logistics of tumor immunology.

Abstract

This article deals with the experimental problems of tumor immunology. It stresses that animal tumors should in their pathogenesis closely reflect the pathogenesis of human cancer because otherwise they may be useless and cloud the issues instead of making useful contributions. Animal tumors for experimental work should be of “spontaneous” origin, metastatie and of low antigenicity. However, the origin of human cancer is in most instances not known, and perhaps no one of the existing models is sufficiently close to human cancer. On the other hand, the article lists all the problems of studying the immunobiology of human cancer which appear to be unsurmountable at this time. Thus, one has to reconsider these experimental problems in view of what is known on the pathogenesis of human cancer. The development of human cancer appears to be a multistep process which takes many years (decades) before the disease becomes manifest. The respective roles of chemical carcinogens, viruses or other damages are uncertain at present, but perhaps viruses do play a role as initiators in early life as suggested by the evidence obtained for the Epstein-Barr virus. Immunosurveillance in the classical sense, i.e., being a reaction of T-dependent lymphocytes, does not appear to play a major role in the prevention of tumors, whereas the role of other cells, such as natural killer cells and macrophages, or soluble mediators, such as interferon, in “anti-tumor surveillance” needs extensive further scrutiny. If these hypothetic considerations (i.e., role of a virus in tumor initiation and role of nonspecific defense mechanism in antitumor surveillance) will receive further support, studies of primary antiviral defense mechanisms will turn out to be of utmost importance. In the conclusions, we line out that it is more important to reconcile the theories of “tumor immunology” with the concepts of carcinogenesis than with the concepts of general immunology. The latter are, of course, of high biologic interest and of great importance but they may not apply to the pathogenesis of tumors, and immunologic mechanisms may not contribute to the defense against cancer.