The concept of immunological surveillance

Subversion of host defense mechanisms by murine tumors. I. A circulating factor that suppresses macrophage-mediated resistance to infection

The subcutaneous injection of cells of any one of five unselected murine tumors resulted very rapidly in the liberation into the circulation of a small molecular weight factor that severely impaired the capacity of the host to resist experimental infection with Listeria monocytogenes and Yersinia enterocolitica. It was found that the factor appeared in blood within 8 h of injecting tumor cells subcutaneously. That it possessed potent physiological activity was evidenced by the demonstration that an infusion of as little as 0.015 ml of tumor-bearer serum strikingly suppressed the capacity of normal recipients to resist bacterial infection. It was reasoned on the basis of the knowledge that the only cells in mice with the capacity to destroy Listeria are macrophages, that suppression of antibacterial resistance was caused by the ability of the tumor-suppressor factor to interfere, either directly or indirectly, with the antibacterial functions of these mononuclear phagocytic cells. The results are consistent with the hypothesis that at least some malignant neoplastic cells are naturally selected to avoid destruction by native and acquired antitumor mechanisms of mononuclear phagocytes.

The carcinogenicity of anticancer drugs: a hazard in man

The carcinogenic potential of anticancer drugs is discussed in the light of selected basic principles of chemical carcinogenesis. Anticancer drugs which act by alkylation and/or by binding tightly to DNA frequently cause cancer in experimental animals and may be carcinogenic in man. In addition, certain anticancer drugs act as cocarcinogens in experimental systems and augment the tumorigenicity of chemical carcinogens. Host determinants are important in chemical carcinogenesis. Many chemical carcinogens and anticancer drugs require metabolic activation by microsomal enzymes. Studies in twins have shown interindividual variation of drug metabolism in man is greater than intraindividual variation caused by exogenous factors. Therefore, certain individuals may be unusually susceptible to the carcinogenicity of anticancer drugs on a pharmacogenetic basis. Age is also a host determinant. At a given total dose level, age at first exposure to chemical carcinogens has been shown to be an important risk factor in experimental studies and in some epidemiologic investigations in man. Therefore, children may be especially susceptible to the carcinogenicity of anticancer drugs. These treated children have the potential of a normal lifespan; the latency period between initial exposure to a carcinogen and clinical evidence of cancer in man is long, usually 2-5 decades. The problems involved in extrapolating data of carcinogenicity in experimental animals to man are discussed. A single drug may have multiple consequences in experimental studies; for example, actinomycin D can act as an anticancer drug, an anticarcinogen, and a carcinogen. These uncertainities and the clinical results concerning second neoplasms following cancer therapy in both children and adults clearly indicate the need to follow carefully long-term survivors who have received cancer therapy.

Development of an effective treatment program for childhood acute lymphocytic leukemia: a preliminary report

The development of an effective therapeutic regimen for acute lymphocytic leukemia (ALL) of childhood is described. By careful surveillance of toxicity and efficacy, positive modifications of treatment strategy were achieved without resorting to classically randomized trails. Teh resultant protocol utilizes vincristine-prednisone induction followed by asparaginase consolidation, intensive intermittent combination maintenance chemotherapy with adriamycin as a major component, and cranial radiotherapy plus intrathecal methotrexate for central nervous system prophylaxis. Preliminary analysis suggests that this regimen may result in prolonged continuous complete remission in at least 80% of children with ALL.

Inhibition of sensitization of T-cells by alpha-fetoprotein

A two-phase model of allograft immunity was studied. In the first phase, specific immune T-cells were generated by incubation of responder cells with mitomycin-C treated allogeneic stimulator cells of the same H-2 type as mouse mastocytoma tumor cells. In the second step, the ability of the sensitized cells to kill Cr51-labelled P-815 mastocytoma cells was assayed. Alpha-fetoprotein (AFP) was shown to inhibit the generation of immune cytotoxic T-cells at low concentrations (1-100 ng/ml) when added at the beginning of the first phase. When added at the end of the first phase or in the second (killing) phase, AFP was found to have no significant effect on cytotoxicity, indicating that it did not inhibit the killer T-cell once it was generated.

Immunosurveillance of naturally occurring feline leukemia

When compared to their housemates that subsequently developed leukemia, cats that remained healthy had five-to tenfold higher (geometric mean) humoral antibody titers to the feline oncornavirus-associated cell membrane antigen. This is compatible with the application of the immunosurveillance hypothesis to the natural development of leukemia in an outbred mammalian species.

Increased incidence of malignancy during chronic renal failure

The incidence of cancer in 646 dialysis/transplant patients before uraemia developed, during the period of progressive uraemia, and post-transplantation was compared. 10 tumours (3 breast, 2 kidney, 1 leukaemia, 1 lung, 1 insulinoma, 1 thyroid, 1 cervix in situ) developed in 9 patients during the period of progressive uraemia, a significant increase over the expected number in the age-matched general population. 6 of these patients have received transplants and have no evidence of recurrent disease 6 months to 4 years post-transplantation. 11 de-novo tumours have developed in 530 transplant recipients (4 cervix in situ, 2 skin, 2 reticulum-cell sarcoma, 1 lip, 1 dysgerminoma, 1 colon)--a significant increase over the age-matched general population. The cancers in the uraemic patients are relatively common types of mesenchymal tumours while the cancers in the transplant recipients are epithelial and lymphoproliferative. This difference may reflect the presence of the graft in the transplant patient or may be due to different patterns of immunosuppression in these two populations.

Nephrogenic adenoma of bladder in immunosuppressed renal transplantation

A case of nephrogenic adenoma is reported in an immunosuppressed renal transplant recipient. The nature of the lesion is discussed, and a possible relationship between benign tumors and impaired immunologic surveillance is considered.

Serial studies of immunocompetence of patients undergoing chemotherapy for acute leukemia

Immunocompetence was followed serially for 1 yr from the onset of treatment in 55 adult patients with acute leukemia. The tests used were delayed hypersensitivity responses to a battery of five recall antigens (dermatophytin, dermatophytin 0, candida, streptokinase-streptodornase, and mumps) and in vitro lymphocyte blastogenic responses to phytohemagglutinin and streptolysin 0. There was a strong correlation between immunocompetence at the start of treatment and a good prognosis; 32/39 patients who subsequently entered remission were initially immunocompetent compared to 4/15 who failed to enter remission. In the complete remission group there was a decline in competence starting from 2 to 5 mo after the onset of treatment. In those who remained in remission for 1 yr, competence recovered at 6 mo and remained vigorous thereafter. In those who relapsed before 1 yr, the decline in competence occurred 1 mo before relapse and competence continued to decline progressively during the 1 yr follow-up period. These studies suggest that therapeutic approaches which restore immunocompetence or prevent its decline will improve both the remission rate and the remission duration of patients with acute leukemia.

Tumor development after 3-methylcholanthrene in immunologically deficient athymic-nude mice

Athymic-nude (nu/nu) mice and normal (nu/+) mice showed no differences in either latent period or incidence of local sarcomas or lung adenomas within 120 days after administration of 3-methylcholanthrene at birth. However, nu/nu mice were incapable of rejecting allogeneic skin grafts for the duration of the experiment. These results argue against an active role of thymus-dependent immunity as a surveillance mechanism preventing tumor development.

Intracranial reticulum cell sarcoma associated with immunoglobulin A deficiency

A case is reported of a 46 year old woman who died after a five month illness characterized by focal neurological signs, evidence of meningeal irritation, and the finding of `blast' cells in the CSF. Immunoglobulin A was consistently absent from her serum and secretions. Necropsy showed extensive infiltration by a reticulum-cell sarcoma of the subarachnoid space, with tumour nodules on several cranial nerves and tumour infiltration of the tuber cinereum. The significance of the association between immunoglobulin A deficiency and neoplasia is discussed.

Thymus-derived rosette-forming cells in various human disease states: cancer, lymphoma, bacterial and viral infections, and other diseases

Lymphocytes that bind in vitro to sheep erythrocytes in a rosette formation are thymus-derived. A modified technique that does not detect the total number of rosette-forming cells (RFC) was used to study normal subjects and various disease states. Of 100 healthy subjects, 95 had more than 15% RFC (mean 28.4+/-6.5%). We studied 104 patients with solid tumors, who were classified according to clinical status and stage of therapy. Of 19 newly diagnosed patients, 13 had less than 15% RFC. Of 44 untreated patients undergoing relapse, 32 had less than 15% RFC. In both categories, patients with metastases had fewer RFC than patients with localized disease. 11 patients were studied 2 wk after cessation of therapy; four of them showed less than 15% RFC. Only one of 30 patients in remission had less than 15% RFC. In seven patients followed for various periods of time, the numbers of RFC correlated generally with clinical status. 11 patients with chronic lymphatic leukemia had very low percentages of RFC. 21 of 21 patients with symptoms of viral upper respiratory diseases had less than 15% RFC. RFC returned to normal values between 5 days and 7 wk after disappearance of clinical symptoms. 20 patients with bacterial infections had normal numbers of RFC. Of 25 patients with miscellaneous nonimmunologically related diseases, two had low numbers of RFC. It appears that the percentage of RFC may be valuable in evaluating not only immunological defenses but also the status of patients with solid tumors, lymphomas, viral diseases and, perhaps, bacterial infections.

Immunologic rejection of diethylnitrosamine-induced hepatomas in strain 2 guinea pigs: participation of basophilic leukocytes and macrophage aggregates

The morphologic events associated with the immunologic rejection by strain 2 guinea pigs of ascites variants of two lines of diethylnitrosamine-induced tumors have been studied by light and electron microscopy. Tumor injection sites in the skin of control animals exhibited clusters of viable, actively mitotic tumor cells along with a modest inflammatory infiltrate composed of lymphocytes, macrophages, neutrophils, and rare basophils. In contrast, similar injections of either tumor line in specifically sensitized guinea pigs elicited typical delayed-type skin reactions associated with tumor cell necrosis and a more extensive inflammatory infiltrate including a selective increase in the number of basophilic leukocytes (12%, line 1, or 23%, line 10, of total inflammatory cells). That basophils may have a role in tumor resistance in vivo is suggested by the close anatomic associations observed between basophils and tumor cells, and by the fact that basophils were the only inflammatory cell to demonstrate a relative increase in frequency in the lesions of sensitized as compared with control animals. Moreover, intraperitoneal injection of line 1 tumor in specifically sensitized animals elicited a striking basophilia within 24 h. Unlike macrophages, basophils did not phagocytose tumor cells but did evidence occasional extrusion of granules and frequently exhibited loss of granule staining density, a change that may be related to release of mediator substances. Electron microscope studies of line 1 tumor rejection in the peritoneal cavities of specifically sensitized guinea pigs demonstrated aggregations of "activated" macrophages, lymphocytes, basophils, and damaged or dead tumor cells. These aggregates, held together by complex interdigitations of macrophage villi, closely resembled those occurring in vitro among peritoneal exudate cells whose migration from capillary tubes was inhibited by migration inhibition factor (MIF). Moreover, cells in these aggregates, as well as macrophages inhibited by MIF in vitro, lacked a normal coating of cell surface material.

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.