The microglial/macrophagic response at the tumour-brain border of invasive meningiomas.
OBJECTIVE
Little is known about the immune response of the brain to invasive meningiomas. The present study was based upon the hypothesis that the microglial/macrophagic response towards brain-invasive meningiomas is dependent on the intactness of the pial-glial basement membrane.


METHODS
We immunostained sections from 40 brain-invasive meningiomas that were graded according to World Health Organization (WHO) 2007 criteria. Thirty-three tumours were histologically WHO grade II (18, 'otherwise benign', and 15, 'otherwise atypical'), and seven, grade III. Microglial/macrophagic cells were labelled with antibodies directed against major histocompatibility complex class II, CD68, CD14 and CD163. Anti-collagen IV was used to visualize basement membranes.


RESULTS
Twenty-five per cent (10/40) meningiomas (1/18 WHO grade II 'otherwise benign', 3/15 grade II 'otherwise atypical' and 6/7 WHO grade III) contained microglial/macrophagic cells at the tumour-brain border. The presence of these cells correlated with the absence of the pial-glial basement membrane (BM) and with WHO grade III. The monocytic response was of two kinds: one consisted of a dense layer of mononuclear cells at the tumour-brain border in nine cases, the other of an elevated number of microglial cells expressing CD14 or CD163 (two cases).


CONCLUSIONS
The immune response at the tumour-brain interface correlates with the absence of the pial-glial BM and with malignancy grade. It remains to be established whether the mononuclear cells at the tumour-brain border are native microglia or blood-derived macrophages.
Grund
S
S
Institute of Brain Research, Univeristy of Tübingen, Tübingen, Germany.
Schittenhelm
J
J
Roser
F
F
Tatagiba
M
M
Mawrin
C
C
Kim
Y J
YJ
Bornemann
A
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D001485:Basement Membrane / Q000276:immunology; D001921:Brain / Q000276:immunology* / Q000378:metabolism; D001932:Brain Neoplasms / Q000276:immunology*; D005802:Genes, MHC Class II; D006801:Humans; D007150:Immunohistochemistry; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008264:Macrophages / Q000276:immunology*; D008579:Meningioma / Q000276:immunology*; D017628:Microglia / Q000276:immunology*; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology; D010841:Pia Mater / Q000276:immunology; D011956:Receptors, Cell Surface / Q000378:metabolism; D000098902:CD163 Antigen; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D018950:Lipopolysaccharide Receptors; D011956:Receptors, Cell Surface; D000098902:CD163 Antigen; C067980:CD68 antigen, human; D000097382:CD68 Molecule