悪性脳腫瘍患者における免疫抑制機構の研究

A NALYSIS OF IMMUNOSUPPRESSIVE MECHANISM IN THE PATIENTS WITH MALIGNANT BRAIN TUMORS

　抄録　悪性脳腫瘍患者にみられる免疫不全に関しての検討を目的に，免疫抑制細胞に主眼をおいて，患者の免疫調節機構の研究を行った。悪性glioma患者62例の検討より，患者末梢血リンパ球のConcanavalinA誘導suppressor能は有意に増強しており，その中に，健常人のリンパ球幼若化能を抑制する細胞群を認めた。この抑制活性は，nylon-wool column非付着性の細胞群に強く認められ，腫瘍から誘導活性化され，主要組織適合遺伝子複合体のバリアを超えて働くと考えられた。単クローン抗体を用いた検討より，この抑制細胞はLeu 2a陽性T細胞と考えられ，Leu 3a対Leu 2a陽性T細胞比は，健常人1.84±0.34，悪性glioma群1.21±0.34，転移性脳腫瘍群1.01土0.44となり，悪性脳腫瘍群での，相対的なsuppressor能の優位が示唆された。更に，悪性glioma患者群の臨床経過中での変動を検討すると，mass effect増強，全身状態の悪化，病期の進行に伴って，この比率は低下する傾向があり，suppressor能の優位が，患者の免疫不企の一因と考えられた。

Immnosuppressive mechanisms in patients withmalignant brain tumors were studied with the useof a nylon wool column and monoclonal antibodies.Peripheral blood lymphocytes (P.B.L.) from thepatients (82 malignant gliomas,65 metastatic braintumors) were tested for their ability to inhibitlymphocytoblastogenesis, and reacted with mono-clonal anti Leu 1,2a and 3 a antibodies to iden-tify the subsets of T lymphocytes. Depression ofthe lymphocytoblastogenesis was detected signifi-cantly by the patients'P.B.L. passed through thenylon-wool column, but not detected by that ad-hering to the column-This suppressor cell activitywas shown to do its work (over the barrier ofmajor histocompatibility complex, and seemed tobe associated with Con. A-induced suppressor cellactivity. Especially, in the patients with malignantgliomas., the suppressor T cells seemed to be in-duced by tumor cells, and mediate the noted im-mnodepression. Furthermore, analysis of T cellsubsets using monoclonal antibodies showed thatthe suppressor cell activity in the patients withmalignant gliomas seemed to be closely correlatedwith Leu 2 a⁺cells, and the Leu 3 a⁺/Leu 2 a⁺ratiodecreased with tumor loads suggesting that thesuppressor T cells are more dominant than thehelper T cells, These immnological studies helpto advance therapeutic protocols of the patients,because suppressor cells may be related to theescape mechanism of matignant brain tumors.