Cytotoxic immune response of meningioma patients towards allogeneic and autologous tumour cells before and after surgery

MGEA6 is tumor-specific overexpressed and frequently recognized by patient-serum antibodies

Tumorigenesis of meningioma has been associated with chromosome 22, most notably the NF2 gene, but additional genes have also been implicated in meningioma development. Previously, we have cloned the cDNAs for the meningioma expressed antigen 6 (MGEA6) and its splice variant MGEA11. Here, we show that antibodies against recombinantly expressed MGEA6/11 are found in 41.7% (10/24) of the sera from meningioma patients and in 2/8 sera of glioblastoma patients, whereas no response was seen in 12 sera from healthy persons. Western-blot analyses using generated polyclonal antibodies, revealed overexpression in meningioma and glioma tumor samples compared to normal brain. Immunohistochemical staining of tissue sections confirms reactivity in meningioma tumor cells and tumor cells of glial origin. We found no reactivity to normal astrocytes and only faint reactivity to normal leptomeninges. Sequence analysis predicted membranic localization of MGEA6/11, that was confirmed by cell fractionation. The immune response to MGEA6/11 is frequent in both meningioma and glioma patients and may likely be attributed to overexpression of the MGEA6/11 protein in the tumor cells.

Probing the human natural autoantibody repertoire using an immunoscreening approach

While an increasing number of studies report the presence of antibodies capable of recognizing self-antigens, the function of these natural autoantibodies remains elusive. A variety of concepts has been advanced ranging from evolutionarily tolerated but non-functional natural autoantibodies to autoantibodies effecting various biological functions. Known IgM, IgG, and IgA natural autoantibodies are directed against various antigens, including nuclear and cell surface proteins. To explore further autoantibodies and their autoantigens, we employed an immunological screening method called SEREX recently used to characterize tumour-expressed antigens eliciting an immune response in patients [1]. Sera from 12 individuals were used to screen a cDNA expression library prepared from a cytogenetically normal meningioma to identify antigens reactive with normal human sera from individuals without obvious disease. Nineteen reactive normal antigen clones were identified representing 15 different antigens, including nine genes with known functions, five genes with unknown functions, and one gene with a novel sequence not present in the databases. Of the 12 individual normal sera tested, 75% were reactive to one or more of the 15 different antigens with two highly reactive sera demonstrating reactivity with 33% of the antigens. When screening the same meningioma expression library with serum from the patient, eight antigens were identified that were totally different from those identified using sera from normal individuals. This SEREX immunological screening method presents a new option for probing the natural autoantibody repertoire and identifying normal antigens whose functions may provide additional insights into how natural autoantibodies effect various biological functions.

Immunopathological significance of IgG in meningioma in relation to the pseudopsammoma bodies

We described two histochemical patterns of IgG deposits in meningioma and discussed the pathogenesis of IgG deposits. In meningioma with pseudopsammoma bodies, IgG was secreted from tumour cells which differentiated to secretory epithelial cells, and was found to deposit in the pseudopsammoma bodies. However, in meningioma without pseudopsammoma bodies, IgG was derived from plasma and became deposit around the blood vessels in the meningioma tissue.

Human intracranial tumors: effect of autologous serum addition on leucocyte migration inhibition

42 human intracranial tumours were investigated by the leucocyte migration inhibition technique at various antigen concentration with and without autologous serum addition. A correlation was found between migration rate and antigen concentration. Autologous serum addition resulted in a non-specific stimulation of migration, however, stimulation by immune complexes was also present. Migration stimulation, as an in-vitro-equivalent of immunologic tumor enhancement, is discussed.

The utilization of native glioma antigens in the assessment of cellular and humoral immune responses in malignant glioma patients

Cellular and humoral components of the immune response have been studied preoperatively, concurrently, and serially in patients with malignant glial neoplasms. In order to assess titres of circulating antibodies to tumour cell constituents an indirect immunofluorescent technique was applied to single cell suspensions and snap frozen cell smears. In an allogeneic system, 49% of 47 test and 7% of 124 control sera gave a positive response to cytoplasmic components. The leucocyte adherence inhibition assay was applied to study 39 test and 64 control patients. Significant non-adherence of leukocytes was observed in 77% of test cases. Control parameters indicated specificity of the response. Simultaneous assessment in 28 test patients yielded a positive response for one or both assays in 89% of cases..

Immunohistochemical demonstration of IgG in meningioma

Twenty human meningiomas were examined for IgG and IgM by the direct immunofluorescence of immunoperoxidase methods, or both. IgG was conspicuously found in and around the blood vessels, whorls, and psammoma bodies. It was also clearly present on the cytoplasmic membranes of the tumour cells. On the other hand, IgM was seen only within the blood vessels. Significance of these findings is briefly discussed including possible humoral immune reactions in regard to whorl and psammoma body formation in meningioma.

Evaluation of the humoral response of meningioma patients to possible common tumour-associated antigens

The humoral response of 39 meningioma patients to possible tumourassociated antigens was studied by means of an antibody dependent cell mediated cytotoxicity test (ADCC). Five patients were found to have cytotoxic antibodies against 1 to 10 meningioma cell lines. However, three of these were also cytotoxic against malignant glioma cell lines but not against other unrelated tumours. These results suggest the existence of surface antigens common to meningiomas and gliomas.