Tumor-specific cell-mediated immunity in household contacts of cancer patients

γ-Radiation promotes immunological recognition of cancer cells through increased expression of cancer-testis antigens in vitro and in vivo

Background

γ-radiation is an effective treatment for cancer. There is evidence that radiotherapy supports tumor-specific immunity. It was described that irradiation induces de novo protein synthesis and enhances antigen presentation, we therefore investigated whether γ-radiation results in increased expression of cancer-testis (CT) antigens and MHC-I, thus allowing efficient immunological control. This is relevant because the expression of CT-antigens and MHC-I on tumor cells is often heterogeneous. We found that the changes induced by γ-radiation promote the immunological recognition of the tumor, which is illustrated by the increased infiltration by lymphocytes after radiotherapy.

Methods/Findings

We compared the expression of CT-antigens and MHC-I in various cancer cell lines and fresh biopsies before and after in vitro irradiation (20 Gy). Furthermore, we compared paired biopsies that were taken before and after radiotherapy from sarcoma patients. To investigate whether the changed expression of CT-antigens and MHC-I is specific for γ-radiation or is part of a generalized stress response, we analyzed the effect of hypoxia, hyperthermia and genotoxic stress on the expression of CT-antigens and MHC-I. In vitro irradiation of cancer cell lines and of fresh tumor biopsies induced a higher or de novo expression of different CT-antigens and a higher expression of MHC-I in a time- and dose-dependent fashion. Importantly, we show that irradiation of cancer cells enhances their recognition by tumor-specific CD8+ T cells. The analysis of paired biopsies taken from a cohort of sarcoma patients before and after radiotherapy confirmed our findings and, in addition showed that irradiation resulted in higher infiltration by lymphocytes. Other forms of stress did not have an impact on the expression of CT-antigens or MHC-I.

Conclusions

Our findings suggest that γ-radiation promotes the immunological recognition of the tumor. We therefore propose that combining radiotherapy with treatments that support tumor specific immunity may result in increased therapeutic efficacy.

Is cancer communicable?

Recent developments in cancer epidemiology have led to the possibility of an exceedingly complex communicable factor(s) in cancer etiology. The transmission of such an agent(s) may require a susceptible genotype and/or other promotional events. Likely candidates which support this supposition include: Epstein-Barr virus (nasopharyngeal carcinoma, Burkitt's lymphoma, salivary gland tumor among Eskimos, X-linked lymphoproliferative syndrome of Purtilo); human T-cell leukemia virus (adult T-cell leukemia); acquired immune deficiency syndrome (AIDS), complicated by Kaposi's sarcoma (etiologic agent remains elusive, though epidemiology suggests possible infectious transmission); abnormal immune phenomena in households of Hodgkin's disease patients; and clustering of various types of cancer in spouses, the general population, and families. We have selectively reviewed the literature and evolved an etiologic hypothesis which integrates a communicable agent(s) in concert with genetic and/or environmental carcinogenic interaction which could conceivably explain a significant fraction of the total cancer burden.

Heterozygosity at Gm loci associated with humoral immunity to osteosarcoma

Serum samples from 50 Caucasian patients with osteosarcoma were tested for the presence of antibodies to osteosarcoma-associated antigens (OSAA) and typed for nine Gm markers. A highly significant association was found between Gm 3;5,13,14 and unresponsiveness to OSAA, and between 1,3,17;5,13,14,21 and responsiveness to OSAA. These results suggest the existence of complementary immune response genes which in the heterozygous condition permit a response to OSAA.

Mycobacterium fortuitum pulmonary infection associated with an antigen-selective defect in cellular immunity

In this study we describe the first example of a well documented case of pulmonary infection caused by Mycobacterium fortuitum shown to be associated with an antigen-selective defect in cell-mediated immunity to this organism. Immunologic parameters were evaluated before, during and after antibiotic treatment with amikacin. A defect in cellular immunity to purified protein derivative from Myco. fortuitum, shown to be antigen-selective as indicated by normal responsiveness to purified protein derivative from Mycobacterium tuberculosis and several other common recall antigens, accompanied the prolonged infection by this organism. During the first three months of treatment with amikacin, the patient's clinical status improved coincident with the eradication of the organism from the sputum. During the next three months of therapy with amikacin, however, a generalized defect in cellular immunity developed, and the lung disease again progressed. The deteriorating clinical condition was presumably related to a generalized cellular immune anergy or hyporesponsiveness induced by the amikacin therapy. After three more months of treatment, the organism became resistant to the drug and reappeared in sputum cultures. Since amikacin therapy was discontinued, the patient's general immune responsiveness returned to normal. He did, however, remain unresponsive to purified protein derivative from Mycobacterium fortuitum.

Antiglobulin antibody in the sera of contacts of children with leukaemia

Healthy adults (parents, neighbours, and hospital staff) in close contact with children with leukaemia were found to have a high incidence of positive latex agglutination antiglobulin tests (probably an IgM antiglobulin antibody). This may explain a previous report of a high incidence of IgM anti-EB virus antibodies in parents of leukaemic children, which our results did not confirm (IgM antiglobulin, reacting with IgG anti-EB virus, could have been misinterpreted as IgM anti-EB virus). The antiglobulin antibody probably represents a nonspecific response to an infective agent. Other hospital staff, including those exposed to nonleukaemic children with infections, had a much lower incidence of the antibody, and it may represent a response to the leukaemic process itself, rather than to the infections to which such children are prone. Some leukaemic children have a similar antibody.

A study of false positive and negative responses in the tube leucocyte adherence inhibition (tube LAI) assay

A panel of 5 different breast-cancer and 2 other cancer extracts was used to clarify the false-negative responses in patients with Stage I and II breast cancer and the false-positive responses in control subjects. Most patients with Stage I and II breast cancer who had an initially negative LAI response were positive when tested against the panel. The false negatives occurred because of (1) the experimental errors of the assay; (2) changes in the antigenic strength of the extracts; (3) antigenic heterogeneity of a few tumours and (4) lack of tumour-specific reactivity of the host. 3% of control subjects had a false-positive LAI response. The leucocytes from most of these positive patients did not react to the panel of antigens, and hence the false positives appeared to result from experimental error. In-hospital patients with benign breast disease had a 12% positivity rate when initially assayed, and 63% of these patients reacted to the panel of breast-cancer antigens. Those patients with benign breast disease who reacted to the panel of breast-cancer antigens had cytophilic anti-breast-cancer antibody in their serum; their leucocyte LAI reactivity was blocked in an immunologically specific manner by serum from advanced Stage IV breast-cancer patients; their leucocytes reacted to extracts of breast cancer and not fibrocystic breast tissue; their leucocyte reactivity was blocked by isolated breast-cancer TSA that was linked to beta 2 microglobulin, but not by normal breast-tissue proteins; and the kinetics of the LAI response after excision of the breast mass was identical to that observed with breast-cancer patients after mastectomy. In these patients, the breast tissue within the breast lump expressed breast TSA similar to unequivocal breast cancer.

Concomitant presence of tumor-specific cytotoxic and inhibitor lymphocytes in patients with osteogenic sarcoma

The lack of detectable tumor-specific cytotoxicity by the peripheral blood lymphocytes of patients with cancer may be due to a lack of cytotoxic lymphocytes or the presence of suppressor lymphocytes that inhibit cytotoxic cells. Unfractionated peripheral blood lymphocytes from 12 of 28 patients with osteogenic sarcoma were cytotoxic to osteogenic sarcoma cells in vitro (P less than 0,001). When the peripheral blood lymphocytes from patients whose lymphocytes were not cytotoxic underwent fractionation, a tumor-specific cytotoxic subpopulation was isolated from 11 of 13 patients (P less than 0.0001). Lymphocytes that inhibited cytotoxic activity of autologous tumor-specific cytotoxic lymphocytes were found in four of 10 patients with osteogenic sarcoma but not in six normal controls. Inhibitor lymphocytes form rosettes with sheep erythrocytes and adhere to nylon, whereas cytotoxic lymphocytes have a receptor for C3 but no surface immunoglobulin. The lack of tumor-specific lymphocytotoxicity in some patients can be due to inhibitor lymphocytes.

Sensitisation of neuroblastoma patients and related and unrelated contacts to neuroblastoma extracts

Sensitisation to neuroblastoma extracts was tested by the leucocyte migration inhibition technique in 8 neuroblastoma patients, 22 relatives, and 49 unrelated contacts. All three groups showed a high frequency of positive reactions compared with 61 controls having no exposure to neuroblastoma. The frequency of sensitisation could be related to closeness of contact, but the nature of the sensitising material and its mode of transmission are unknown. Virus studies by the sensitive techniques of tumour virology are suggested. The absence of case clustering and the low familial incidence of neuroblastoma indicate that simple exposure to the tumour is not a major oncogenic factor.

Specific responsiveness of leukocytes to soluble extracts of human tumors

The leukocyte adherence inhibition (LAI) method was studied with respect to its specificity in detecting responses to extracts of tumor tissues or normal lymphocytes. Responses of cells from normal persons were within 10% of each other whether incubation was carried out with culture medium alone or with any of the extracts. The same was true of cells from 78 cancer patients unless the cells were incubated with extracts of the same histologic type as their own. In the latter case, statistically significant responses occurred in 95% of the 110 analyses done. Negative responses were given by cells from 14 patients tentatively diagnosed as having breast carcinoma but whose lesions later proved benign. There was one positive response inconsistent with the diagnosis. Of 29 normal individuals known to have been exposed to tumors or tumor extracts, 11 responded positively and specifically to the relevant tumor extract. Cells from 12 of 30 multiparous female breast-cancer patients responded to extracts of pooled normal lymphocytes. The results establish that the LAI analysis is an extremely specific means of detecting systemic responses to malignant diseases. In addition, analyses have proven positive in 95% of the cases studied.

Osteogenic sarcoma. Immunologic parameters before and during immunotherapy with tumor-specific transfer factor

18 patients with osteogenic sarcoma were followed by serial measurements in vitro of tumor-specific cell-mediated cytotoxicity and of "active" and total rosette-forming T-cells. 13 of these patients have had or are currently receiving injections of osteogenic sarcoma-specific dialyzable transfer factor derived from healthy donors. In three patients with very small lesions, cytotoxicity was high before amputation and decreased within 2 mo after removal of tumor. Cytotoxicity was low at time of diagnosis in all patients with large tumor masses. The cytotoxicity of the patients' lymphocytes increased after administration of tumor-specific transfer factor in all patients so treated. Patients receiving nonspecific transfer factor showed evidence of declining cell-mediated cytotoxicity. Tumor-specific transfer factor may produce an increase in cell-mediated cytotoxicity to the tumor in patients with osteogenic sarcoma. This possibility is suggested by the pain and edema that occurred in the area of the tumor in patients who had metastatic disease when therapy was started and by lymphocytic infiltrates in the tumor, as well as by the increase in cell-mediated cytotoxicity and the increase in percentage of active rosette-forming cells from subnormal to normal. Serial measurements of cell-mediated cytotoxicity are helpful in monitoring the efficacy of transfer factor and other modes of therapy in these patients, and these measurements are the best available criteria for selection of donors of tumor-specific transfer factor.