Monoclonal antibody analysis of major histocompatibility complex expression in human meningiomas

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.

An immunohistochemical study on HLA-DR expression in human meningiomas

The expression of HLA-DR was examined in 38 cases of meningiomas with the streptavidin-biotin immunoperoxidase method using two monoclonal antibodies to HLA-DR (LN-3 and TAL-IB5) on formalin-fixed, paraffin-embedded specimens. Similar immunoreactivity was obtained with these two monoclonal antibodies. In addition to infiltrated lymphoid cells and perivascular macrophages, tumor cells themselves showed HLA-DR expression in 16 cases (42%) of meningiomas. The rate of HLA-DR-positive cases in the transitional and fibrous subtypes (64% and 67%, respectively) was higher than that in the meningotheliomatous subtype (8%). Spindle-shaped tumor cells were frequently positive for HLA-DR, whereas few of meningotheliomatous cells with plump cytoplasm were positive. Most of HLA-DR-positive cases showed no or scanty lymphoid cell infiltration, and a few cases with marked infiltration of lymphoid cells were variable for HLA-DR expression. These findings suggest little correlation between HLA-DR expression of tumor cells and the degree of lymphoid cell infiltration, but indicate an aberrant HLA-DR expression of tumor cells themselves.