OligodendrogliomaのMBP,GFAP免疫組織化学—細胞分化におけるmyelin-forming gliaに関連して

MBP, GFAP IMMUNOHISTOCHEMISTRY OF OLIGODENDROGLIOMAS WITH RELATIONSHIP TO MYELIN-FORMING GLIA IN THE CELL DIFFERENTIATION

　抄録　Oligodendrogliomaの組織像は，全体的に均一で単調な配列パターンを示すが，その腫瘍構成細胞は決して単一のものではなく，かなりの多形性を呈していることが多い。この多彩な腫瘍細胞の細胞分化の程度を，免疫組織化学的方法で識別できるのではないかとの前提のもとに，13例の手術摘出oligodendro—gliomaについて，ミエリン塩基性蛋白（MBP）およびグリア線維性蛋白（GFAP）の局在を検索した。その結果5例のoligodendrogliomaにMBP陽性細胞の混在が認められた。この陽性細胞は，ミエリン形成期の幼若なoligodendrocyteに極めて類似しており，oligodendrogliomaの腫瘍細胞が，幼若なoligodendrocyteの形質を発現しているものと考えられた。GFAP染色では8例に陽性腫瘍細胞が認められた。このGFAP陽性細胞は，MBP陽性細胞と同様な形態であり区別することは不可能であった。またMBP陽性細胞とGFAP陽性細胞は，同一組織中に相伴って出現する傾向を示し，さらにMBPとGFAPが同一腫瘍細胞内に共存することが強く示唆された。これらのことは正常発生途上において幼若なoligodendrocyteが，MBPとGFAPを同時期に発現することを反映しているものと思われた。

The histologic feature of oligodendroglioma isconstituted by the monotonously arranged sheets of tumor cells intersected with delicate vascular stroma. The shape of the tumor cells is usually uniform and occasionally rather pleomorphic. In order to clarify biological characteristics of the tumor cells at level of cell differentiation, immuno-histochemical stains for myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) with PAP method were performed on 13 oligo-dendrogliomas obtained by surgical removal. The cells stained positive with MBP immunostain were encountered in 5 tumors and their incidence was ranging from 1 % to more than 30 % of all tumor cells. The MBP-positive cells were chara-cterized by having a large clear nucleus with a prominent nucleolus and relatively abundant cytoplasm, that seemed to mimic myelin-forming glia appearing in normal developing brain. The cells with poor cytoplasm or surrounded by a perinuclear halo were MBP-negative, and the pleomorphic cells in majority of anaplastic oligo-dendrogliomas were also negative. On the other hand, with GFAP stain the positive cells were observed in 8 tumors. It is still controversial to interpret the occurrence of GFAP-positive cells in oligodendrogliomas. In this study the GFAP-positive cells were morphologically identical to the MBP-positive cells, so that both MBP and GFAP are supposed to exist in the same tumor cells. It is assumed that some of oligodendro-glioma cells which showed such immunostainabili-ties could possess an intrinsic character to express a phenotype of myelin-forming glia. Possibly, MBP substance is applicable as one of immunohi-stochemical markers for oligodendroglioma cells to indicate a certain cell differentiation.