脳腫瘍の生化学，免疫および組織培養

Brain Tumors:Biochemistry, Immunology and Tissue Culture

I．脳腫瘍の生化学に関する知見

　脳腫瘍の生化学については，髄液中のLDH isozymeに関する研究があるが，これはすでに報告されている^1）2）のできわめて簡単に述べることにする。

　種々の脳腫瘍組織および髄液中の乳酸脱水素酵素（LDHと略す）のisozymeを分離抽出するには，材料を高張polyvinyl pyrolidonで透折濃縮した後，寒天電気泳動を行ない，nitroblue tetrazoliumで染色する。LDH isozymeはWiemeにしたがい陽極側からL₁L₂L₃L₄L₅と名命した。正常脳組織ではL₁からL₄まで少しずつ少なくなつてきて，L₅がごくわずかに認められる。正常髄液ではL₁からL₃まで認められるが，L₄は非常に少なく，L₅は認められない。次に腫瘍の場合，一二の例を示すと，glioblastoma組織のhomogenateでは正常脳組織に比してL₄L₅とくにL₅の増加が著明である。glioblastoma患者の髄液では，L₂がL₁より多く，またL₄L₅，とくにL₅が著明に増加している。hepatomaの脳転位の例においては，腫瘍組織と髄液中のLDH isozymeのpatternはよく似ており，とくにL₄L₅が最も著明に現われる。このようにglioblastomaにしても転位癌にしても一般に悪性の腫瘍の場合には，LDH isozyme，とくにL₄L₅の分画については，腫瘍組織が崩壊してそのLDHが髄液中に現われたと考えられる。そしてこのように髄液中にL₄L₅がはつきり現われるのは悪性腫瘍の場合の特徴であるということができる。一方良性腫瘍の代表であるmeningiomaの場合には腫瘍組織のLDHと髄液のLDHの間に相似がなく髄液のLDH isozymeのpatternは正常のものに近いのである。したがつて髄液中のLDH isozymeのpatternを知ることによつて腫瘍の種類（少なくとも良性が悪性かということ）の診断が可能であると考えられる。

Methods of trypsinization-monolayer culture of the brain tumors have been devised and improved. According to our methods, very good results were obtained in almost all of the various types of gliomas and meningiomas. Successive culture was repeatedly tried and changes in morphological characteristics through generations were described. The longest cul-ture, at present, is four generations, 200 days, in an astrocytoma. Effort to establish strain of the glioma cell is now being continued.

Generation time of the brain tumor cells in the cul-ture was culculated from labelling index of tritiated thymidine in radioautography, Generation time in the monolayer culture was compared with those in other tissue culture methods and the variation of generation-time among these methods was discussed.

Screening tests of the various anticancerous drugs was carried out in monolayer tissue culture of the brain tumors and some contradictlon was found be-tween the results of the test and clinical experience. Cause of this contradiction was discussed and the screening method based on the incorporation of tritia-ted thymidine into the glioma cells in culture was proposed.

History and the mechanism of radiosensitizers was. briefly reviewed and our investigations on one of the radiosensitizers,5-Bromo-2-Deoxyuridine (BUdR) in tissue culture was described.

Tritiated BUdR was confirmed to be taken up in the nuclei of the cultured brain tumor cells and FL cells in radioautgraphy. The cells in vitro took up BUdR and thymidine in the same rate into the nuclei if they have been given in the same concentrations. Whereas, Methotrexate was found to suppress up-take of thymidine and facilitate incorporation of BUdR. The cells which have got BUdR in the nuclei were confirmed to be much more sensitive to x-ray irradia-tion comparing with the control groups in vitro.