脳腫瘍患者の免疫能検査—PHA皮内反応の有用性について

IMMUNOLOGICAL EXAMINATION IN PATIENTS WITH BRAIN TUMOR AND THE USEFULNESS OF PHA SKIN TEST

I．はじめに

　最近の免疫機能検査法の飛躍的な進歩により，いろいろな疾患に免疫学的検討が加えられ，多くの癌患者で免疫応答が解明されてきている。また，免疫学的に特殊な立場にあると考えられていた中枢神経系においても，脳腫瘍の特異抗原が存在する報告があいつぎ，他のがん患者と同じく免疫学的監視機構が低下していることが明らかにされて来た^{3,6,12,15,19,22,25,26,29,30）}。さらに，脳腫瘍患者の免疫学的治療の可能性が追求されている現在^{2,13,18,24,27）}，適確な免疫能を把握することは必要不可欠な事である。

　細胞性免疫能を検査する方法として，in vitroではT-cell検索，末梢リンパ球のブラスト化，マクロファージ遊走阻止試験など，in vivoではPPD,DNCBを代表とする遅延型皮膚反応が広く用いられている^{9,10,22,25）}。その結果でも脳腫瘍患者の細胞性免疫能は一般に低下していると報告されている^{9〜12,22,23）}。

The usefulness of in vivo skin test reaction to phytohemagglutinin to assess cell-mediated im-munity was investigated in 109 subjects, including 37 normal controls, 35 patients without brain tumor and 37 patients with brain tumor. Intradermal injection at forearm of 10 ug of Bacto-phytohemag-glutinin-P (PHA-P) produced an erythema within 24 hours. Upon PHA skin reaction the mean diameter of erythema was 25.3 mm with the normal in the control and 18.6 mm with other diseases than brain tumor, while it was 13. 0 mm with brain tumor. Furthermore when mean diameter of those with longer than 15.0 mm are classified as positive in the PHA skin test, the normal in the control revealed 89.2% positive and the patients with brain tumor indicated only 37.8% positive. A positive reaction was observed in 10 (77.0%) of 13 benign brain tumor and 5 (26.3%) of 19 malignant brain tumor. A correlation was found between in vivo and in vitro responses to PHA, and between PHA and PPD skin reaction.

In repeated PHA skin test at intervals of about one month, the skin reaction to PHA of patients with brain tumor varied depending on the clinical states. Other advantages of this test are no presensitization and it can be used repeatedly.

The PHA skin test is a useful and simple screening test for cellular immune function of patients with brain tumor and as a simple method applicable clinically indicating accurate immuno-reactivity the PHA skin tests have been carried out during the course of treatment with an interval of about one month repeatedly.