Tumor immunity

Reproducibility of the immunofluorescent test for antimelanoma antibodies

The reproducibility of the indirect immunofluorescent test for antibodies to human malignant melanoma cytoplasmic antigens was investigated by testing panels of melanoma and normal sera against cells of each of several different melanomas. Tests were performed in replicate, read blindly by two observers, and repeated on different days. Different observers agreed in the interpretation of replicate assays in approximately 80 to 90% of cases. Variability increased considerably when assays were repeated on different days or when different in as few as 21% of tests. Thus, the results of the indirect immunofluorescent test for melanoma cytoplasmic antibodies must, at the present time, be interpreted with great caution.

Tumor-specific immunity and the Otolaryngologist

It has been known for many years that cell-mediated immune mechanisms are primarily responsible for rejection of normal tissue grafts in genetically dissimilar individuals, and it is now clear that immunity to cancer is mediated in the same way. Malignant tumors have cell surface antigens which are different from those of the tissues from which they arise, hence the term “tumor-specific antigens.” Largely responsible for this discovery was the development of syngeneic (genetically identical) host systems which have permitted assessment of tumor-specific immunity rather than the transplantation antigens of allograft immunity. Host-tumor surveillance is primarily lymphocyte mediated. The humoral immune mechanism is also involved, but the best documented action of humoral factors is interference with cell-mediated tumor destruction by “blocking.” Direct evidence for a host-tumor relationship has led to a resurgence of interest in immunologic therapy for cancer. Prospects for immunotherapy include nonspecific active immunization (i.e., BCG), transfer of lymphocytes or transfer factor, selective elimination or inactivation of humoral blocking material, and prolongation of tumor-specific antigen stimulation by in situ necrosis. At the present time it is unlikely that immunotherapy alone will play a major role in the treatment of gross deposits of cancer, but it may become an important adjunct to surgical therapy by eradicating small populations of tumor cells, both within the surgical field and at distant sites. Theoretically, immunotherapy could solve both of these problems which are the consequences of small undetectable inocula of tumor cells having been deposited at distant sites or in the surgical field. Before immunotherapy can be accepted as a standard form of cancer therapy, it will be necessary to delineate the interrelationships of tumor antigens, cytotoxic antibodies, blocking factors, and delayed type hypersensitivity.

Malignant tumors arising de novo in immunosuppressed organ transplant recipients

De novo malignant tumors have been observed throughout the world in 75 chronic survivors of organ transplantation, including 16 of our own patients. The incidence of tumors was approximately 80 times greater than in the average population in a comparable age range. Chronic uremia may have predisposed to the development of some of the tumors, but this has not yet been proved. It seems clear that the predominant etiology was chronic immunosuppression post-transplantation. Forty-four of the patients had epithelial tumors and in 31 the lesions were of mesenchymal origin. On the average the malignancies appeared 29 months after transplantation. Lymphomas showed an unusual predilection for involvement of the central nervous system. Carcinomas of the skin, lip, and uterine cervix were successfully treated by conventional techniques. On the other hand, carcinomas of the thoracic or abdominal organs and mesenchymal tumors led or contributed to early death in most cases. For this reason drastic reduction or even discontinuance of immunosuppression should be considered in the management of these latter tumors.