ヒト神経膠腫のアルカリホスファターゼ活性に関する組織化学的研究—悪性度による電顕的活性局在の変化

ALKALINE PHOSPHATASE ACTIVITY IN HUMAN GLIOMAS AS REVEALED BY LIGHT AND ELECTRON MICROSCOPY

　抄録　神経膠腫の悪性度による電顕的活性局在の変化を，alkaline phosphatase （ALPase）活性を指標とし，酵素組織化学的方法を用いて検討した。glioma手術例8例（astrocytoma 2,4例，astrocytoma 3，1例，glioblastoma,3例）を対象とした。手術時に摘出した腫瘍組織をアルデヒドにて前固定し洗浄，凍結，未凍結切片を作製，反応液に浸漬した。ALPase活性検出にはクエン酸鉛法（Mayahara et al, 1967）を用いた。反応後，光顕的には硫化アンモニウムにて発色，電顕的にはオスミウム酸固定後樹脂包埋超薄切片を作製して観察した。光顕的には良性（astrocytoma 2），悪性（astrocytoma 3, glioblastoma）のglioma共にALPase活性は血管壁に限局し，両者の間で反応の程度に差異はみられなかった。電顕的にも酵素活性は主として血管内皮細胞に分布していた。良性群では主に血管内皮細胞の基底面形質膜に反応陽性であるのに対し，悪性群では主に腔面形質膜に反応陽性であった。このように悪性度の異なるgliomaの間でALPase活性局在部位が異なることは，gliomaの浸潤性，分化度を検討する上で注目される。またgliomaの悪性化に伴う血脳関門の機能的変化を検索する重要な手掛りを与えると期待される。

Precise localization of alkaline phosphatase (ALPase) activity in human gliomas was examin-ed by light and electron microscopy in associa-tion with malignant transformation, paying much attention to changes in blood-brain barrier.

Materials used were eight cases of gliomas four of which were astrocytoma grade 2, one astrocy-toma grade 3, and three, glioblastoma multiforme, respectively.

Specimens were quickly fixed in cacodylate-buf-fered 2% glutarardehyde at 4℃ for 1 hour and rinsed overnight in the same buffer. Frozen or nonfrozen sections (40 μm thick) were made and incubated at 20℃ for 40 min, and processed for light and electron microscopy.

For the demonstration of ALPase activity, the lead citrate method (Mayahara et al., 1967) was employed.

By light microscopy, ALPase activity appeared to be mainly restricted to the capillary wall.

By electron microscopy, reaction product re-presenting ALPase activity was distributed in the plasma membrane of endothelial cells both in astrocytomas and in glioblastoma.

In astrocytoma grade 2, activity was primarily localized along the abluminal surface of endothe-lia) cells. In glioblastoma, on the other hand, ALP-ase activity was positive on the luminal surface of the plasma membrane of endothelial cells. It was much more intense than that along the ablu-minal surface.

Regional differences in enzyme cytochemistry may represent functional heterogeneity in the endothelial cell membrane.

In brain tumors, changes in distribution patttern of enzyme activitiy were visualized in the present study in association with glioma malignancy. This might represent a functional aspect of changes in blood-brain barrier in human glioma tissue during the course of its malignant transformation.