ヒト脳腫瘍におけるソマトスタチンの局在

LOCALIZATION OF SOMATOSTATIN IN HUMAN BRAIN TUMORS

　抄録　ソマトスタチンは視床下部のほか，中枢神経系，膵島や消化管に広く分布することが知られているが，脳腫瘍における存在はなお十分に明らかでない。これを明らかにする目的で本研究を行った。われわれは，最近3年間に，生検・手術により採取されたヒト脳腫瘍44例，脊髄腫瘍1例について市販キットを用い，PAP法によりソマトスタチンの分布を免疫組織化学的に観察し，インスリン，グルカゴンなどの分布と比較検討した。Astrocytorna，ことにgemistocytic astrocytoma　およびglioblastomaでは，豊富な胞体をもつ大部分の腫瘍細胞とその細胞突起がソマトスタチン，インスリン，グルカゴン陽性であった。また，細胞質に乏しい小型の腫瘍細胞にはこれら物質は弱陽性あるいは陰性であった。陽性物質はいずれも腫瘍細胞胞体にびまん性に認められた。Ependymoma,medulloblastoma,oligodendrogliomaおよびneu—rilemmomaの腫瘍細胞はいずれも陰性であった。陽性細胞の分布からは，これら物質は同一細胞内に共存しているものと思われた。

Although a number of reports demonstrated that somatostatin is distributed widely in the central nervous system, the presence and distribu-tion of somatostatin in the human brain tumors has not been well documented yet. In this report,the immunohistochemical localization of somato-statin in the human brain tumors was studied using the peroxidase-antiperoxidase (PAP) method and compared with the distribution of insulin, glucagon and neurophysin. The main purposes of this study were to analyze the distribution pattern of immunostaining in different types of glial neoplasms.

Fourty-five cases of human intracranial and spinal cord tumors (27 gliomas, 12 meningiomas and six other non-glial tumors) selected mostly from surgical materials were examined for the localization of these peptides. Dako PAP KIT (Dako Corporation) was used for immunostaining and applied to 3 /tm thick sections cut from formalin-fixed, paraffin-embedded tissue.

The results were as follows:

1) A positive immunostaining for somatostatin, insulin and glucagon was found in most of the tumor cells with abundant cytoplasm in astrocyt-omas, particularly in gemistocytic astrocytomas. The immunostaining was prominent in the perikarya and in the cell processes. The fibrillarybackground was also diffusely stained.

2) In glioblastoma multiforme the cytoplasm of gemistocytic cells, large bizarre cells, and fusiform cells exhibited immunoreactivities of somatostatin, insulin and glucagon. Immunostaining for these peptides was less prominent in glioblast-omas than in gemistocytic astrocytomas. Small cells with scanty cytoplasm showed no immuno-staining.

3) Positive reaction to neurophysin was observed only moderately in occasional tumor cells of astrocytomas and of glioblastomas.

4) Ependymoma, oligodendrogliomas and me-dulloblastomas were negative for all four of these peptides examined. However, reactive astrocytes found around tumors showed positive staining for somatostatin, insulin and glucagon. Reaction to neurophysin was negative.

5) Meningiomas of meningotheliomatous type showed positive staining for somatostatin, insulin and glucagon. Neurilemmomas were negative in immunostain for all these peptides.