[Immunochemical and immunological study of human brain tumors]

Invited review. Nervous system antigens

Some of the better characterized proteins (markers) of the nervous system are described. The availability of specific antibodies to these markers has allowed the localization and assay of the proteins in tissue and biological fluids. There is some evidence that autosensitization may occur. Clinical application of these markers includes the evaluation and prognostic significance after stroke and head injury. The diagnostic histopathological use of the markers in the investigation of various tumours is summarized.

Immunological aspects of intrinsic glial tumors

✓ Fundamental concepts of general tumor immunology and modes of immunotherapy are presented. Significant work dealing with the relationship of the immune system to intrinsic glial neoplasms is reviewed in relation to therapeutic applications and future investigative efforts.

Evaluation of the humoral response of glioma patients to a possible common tumor-associated antigen(s)

Cytotoxic antibodies against glioblastoma-associated antigen(s) have been sought for in glioma patient sera. Complement-dependent cytotoxicity (CDC) I and antibody-dependent cell-mediated cytotoxicity (ADCC) assays were used to test sera from 80 patients using 51 Cr labelled target cells derived from eight different glioblastoma lines. As more positive sera were detected with ADCC than with CDC, ADCC assay was used for the remainder of the study. Cytotoxic antibodies were detected in the sera from 8 of 80 glioma patients (10%) by CDC and in 20 of 143 (14%) by ADCC. Fourteen percent of 27 meningioma patients and 16% of 25 normal donors used as controls were found to react in ADCC against the same glioblastoma cell lines. The positive serum samples showed extensive cross-reactions with the different glioblastoma cells, but the pattern of reactivity was different for each serum tested. The antibodies detected did not seem to be directed against tumor-associated antigen(s), since the positive sera were found to have a similar ADCC reactivity against unrelated tumor cells and normal fibroblasts. Moreover, their antiglioma reactivity was absorbed by cells of unrelated tumors and by normal platelets. These results do not support previous reports of specific humoral responses in glioma patients against common tumor-associated antigen(s).

Lymphocytic infiltrates in primary glioblastomas and recidivous gliomas. Incidence, fate, and relevance to prognosis in 228 operated cases

The correlation existing in several human malignancies between lymphocytic infiltration and prolonged survival prompted this study. Two hundred selected patients who were operated on for glioblastoma were reviewed to investigate the incidence of the lymphocytic infiltration in the histological slides and its possible relevance to a better clinical course. The group that exhibited a definite lymphocytic infiltration (Group A, 11.5%) had a significantly longer preoperative history and postoperative survival (p less than 0.01) than the other two groups that presented slight or no infiltration (Group B, 23%, and Group C, 65%, respectively). In addition, biopsies of 28 recidivous gliomas were reviewed to study the fate of this lymphocytic infiltration in relation to time and therapy, such as irradiation and steroids which are known to depress the immune response. The authors found that severe lymphocytic infiltration is a rare immunobiological reaction which significantly improves the prognosis of a malignant brain tumor and seems not to be influenced by time, local x-ray therapy, or steroids.

Glia-specific antigen in the intracranial tumors. Immunofluorescence study

26 gliomas and 14 non-glial tumors were examined for the presence of nervous system specific antigen (CGSA) to assess the antigenic properties of neoplastic tissue in relation to histogenesis and degree of differentiation of tumors. Double layer immunofluorescence (IMF) technique was used for the cellular localization of the antigen. CGSA was found in the cytoplasm of normal, reactive and neoplastic neuroglial cells. Well differentiated astrocytomas showed the strongest IMF reactions and largest number of IMF-positive cells. Tumors with histological signs of anaplasia displayed foci of IMF-negative cells irregularly distributed in the sections. There were no completely negative astrocytomas owing to a marked affinity of the specific astisera to the astrocytic cell line. In the oligodendrogliomas a smaller amount of the antigen was found than in the astrocytomas. Histological evidence of malignancy in these tumors was accompanied by strikingly small number of positive cells and weaker IMF reactions as compared to the well differentiated oligodendrogliomas. Anaplastic gliomas showed only traces of CGSA and non-glial tumors were entirely negative. The results suggest a deficiency of normal antigenic material in the neoplastic glia, particularly of oligodendrogliomas and anaplastic gliomas.

Immunobiology of primary intracranial tumors. Part 3: Microcytotoxicity assays of specific immune responses of brain tumor patients

Fifty-six in vitro microcytotoxicity assays were conducted on 30 patients with intracranial tumors at various times during the postoperative course. Significant specific cellular cytotoxic responses were found in nine of 56 assays, humoral cytotoxic responses in nine of 54 assays, and host effector cell-dependent, antibody-dependent cytotoxic responses in four of 28 assays. Variables that might influence the occurrence of cytotoxicity were studied, and the relationship of these findings to other immune parameters was discussed.

Demonstration of a phase (stage)-specific embryonic brain antigen in human meningioma

The water-soluble antigens of human embryonic brain were studied using a rabbit antiserum to human 8- to 10-week embryonic brain (non-absorbed and absorbed with extracts of human embryonic and adult organs). A phase (stage)-specific brain antigen(s) characteristic for the human 8- to 10-week-old embryo was detected by double immunodiffusion and immunoelectrophoresis in agarose gel. The testing of this anti-embryonic brain serum against saline extracts of human brain tumours (meningiomas, glioblastomas, astrocytomas, neurinomas and brain metastasis of carcinoma) revealed the presence of an "embryonic" antigen in the human meningioma only. Immunochemically this meningioma-associated antigen is identical to a phase (stage)-specific antigen of the 8- to 10-week embryo.

Two separate membrane-bound antigens on human glioma cells in tissue culture detected with sera from glioma patients by immunofluorescence

Sera from patients with malignant and benign gliomas, as well as sera from healthy donors, were tested by indirect immunofluorescence to detect antibodies against antigens on the membrane of glioblastoma, astrocytoma, reactive perimetastatic glia, normal glia and fibroblasts in tissue culture. Sera from glioblastoma patients reacted with glioblastoma, astrocytoma and reactive glial cells; they were negative on normal glia and on fibroblasts, whereas sera from astrocytoma patients were unreactive. Sera from control patients were positive in 7 out of 15 cases, although some differences were noted in the pattern of reaction. Absorption with astrocytoma powder, with glioblastoma and reactive glial cells indicated that all the positive cell lines expressed an astrocytoma-associated antigen "A", while only glioblastoma lines and reactive glial line shared a supplementary antigen "G". Neither of these 2 antigens seemed to be present in significant amount in normal brain, since the positive reactions could not be abolished by absorption with normal brain powder. The relationship between these 2 antigens and the process of increasing malignancy in gliomas is briefly discussed.

Human meningioma antigens

Sera from patients with various types of central nervous system tumors display antibodies reactive in serologic assays with cells and extracts derived from human brain neoplasms. Soluble antigens extracted and purified from surgical specimens of human meningiomas (MSA) were used to test for precipitating antibodies in sera from patients with various histologic types of brain tumors, non-neural solid tumors and from normal donors. Blind studies by immunodiffusion (ID) showed that 63% (15/24) of meningioma patients, 53% (9/17) of glioma patients and 17% (5/29) of patients with various other brain neoplasms had antibodies that reacted with two of three meningioma-associated antigens. Sera from normal donors and patients with non-neural solid neoplasms reacted to a limited extent (7/118) with another of these tumor-associated antigens. Cross-reaction and absorption studies revealed that the three meningioma-associated antigens were detecting different antibodies. None of the antigens was related to HLA antigens or to the human non-neurotropic viruses used in our assays.

Glioblastoma multiforme: a controlled trial to assess the value of specific active immunotherapy in patients treated by radical surgery and radiotherapy

The results are reported of a randomized prospective clinical trial carried out to assess the value of specific active immunotherapy using irradiated autologous tumour cells in patients with glioblastoma multiforme treated by radical surgery and post-operative irradiation. The results in 62 patients show no statistically significant difference in survival between the group receiving adjuvant autologous tumour cells and those treated with surgery and radiotherapy alone. All 27 patients receiving tumour cells were dead at 30 months, whereas 7 of the 35 controls were alive at this time. The results were considered sufficiently discouraging to abandon the trial at this stage on the grounds that there was sufficient evidence in this study that the administration of irradiated autologous cells was of no benefit to patients with high grade astrocytomata.