Antigens in human glioblastomas and meningiomas: search for tumour and onco-foetal antigens. Estimation of S-100 and GFA protein

Abstract

Summary.-Extracts of glioblastomas and meningiomas were analysed by quantitative immunoelectrophoresis for the presence of foetal brain antigens and tumourassociated antigens, and levels of 2 normal brain-specific proteins were also determined. The following antibodies were used: monospecific anti-S-100 (glia specific); monospecific anti-GFA (glial fibrillary acidic protein), (astroglia specific); polyspecific anti -foetal brain (12-16th week of gestation); a polyspecific anti-glioblastoma antiserum, absorbed with insolubilized serum, haemolysate and normal brain extract; polyspecific anti-meningioma antiserum, absorbed as for glioblastoma antiserum; monospecific anti-a-foetoprotein; and monospecific anti-ferritin. Using the antibodies raised against the tumours, several antigens not present in foetal or adult normal brain were found in the glioblastomas and the meningiomas. These antigens cross -reacted with antigens present in normal liver and were therefore not tumour-associated. S-100 was found in glioblastomas in approximately one tenth the amount in whole brain homogenate, whereas GFA was found 2-4 times enriched. The 2 proteins were absent in meningiomas. The possible use of the GFA protein as a marker for astroglial neoplasia is discussed.Five foetal antigens were found in foetal brain, but none in the tumours. a-Foetoprotein could only be demonstrated in foetal tissue extracts, including foetal brain, but not in tumours. Ferritin was detected in all tumour extracts, although the amounts determined were unrelated to histological tumour type.

Malignancy markers in the cerebrospinal fluid

“…Its presence in CSF is associated with cell damage [58] and the level rises, for example, in compression due to a tumour [82]. The specificity for malignancies is low [24]; although present in gliomas, it is absent in meningiomas. Malignant melanomas, like many extracranial tumours, show increased S-100 protein levels [19,32].…”

“…Ferritin has been found in the CSF of patients with brain tumour but tissue concentration shows no correlation with malignancy [24]. In neuroleukaemias and other lymphoproliferative disorders with CNS involvement there are values suggestive of increased CSF levels [23,94] but the results are not consistent.…”

Human glioma tumour-associated antigens

“…a2-Glycoprotein is another glia-specific protein found predominantly in oligodendrocytes [43] and associated with gliogenous tumours; its amount also correlates inversely with the malignancy of the tumour [44]. S100 protein is present in normal brain [29], and $100 levels in glial tumour tissue are inversely proportional to the degree of malignancy [7,12]. However, in glioma cell lines carried in vitro the presence of $100 protein has been reported by some authors [8], but was not found by others [1].…”

Neuropeptides in neurological tumours

“…Tumours of the central nervous system have been investigated previously to establish the presence of a number of markers of astrocyte function such as S-100 protein (1,2), glutamine synthetase and glial fibrillary acidic protein (GFAP) (3,4,5). Extreme variability has been demonstrated in the expression of these antigens in human tumours (5).…”