不安定狭心症における血中インターロイキン6測定の意義

Elevated Plasma Interleukin-6 Levels in Patients with Unstable Angina Pectoris

　目的：不安定狭心症（UAP）と急性心筋梗塞症（AMI）で血中IL−6を測定し，心筋細胞障害の役割を検討した．対象・方法：UAP20例，AMI10例を対象とし，UAPは血清CK値が正常の2倍以下で変動したA群と，しなかったB群に分け検討した．IL−6はELISA法で，発症6hr後より3hr毎に24hrまで測定し，ピーク値（P），ピーク時間（Tp）および各時間のIL−6値の総和Σ₂₄を算出した．結果：A群のP値（114±59ρg／ml）とΣ₂₄値（480±255ρg／ml）は他の群より有意に高く，A群とB群のTp時間（それぞれ9.3±4.1hr,8.7±3.6hr）はAMI群より短かった．結語：ヒトの心筋虚血時にIL−6は血中に増加した．AMIでIL−6の上昇は緩徐であったのに対して，不安定狭心症では発症早期にピークを認め，そのうちCK値が変動する例ではピーク値とΣ₂₄値が高かった．一部のUAPで，強い心筋虚血が刺激となりIL−6が心筋細胞自体から産生され，心筋細胞障害発生の一因となる可能性が示唆された．

In 30 patients (age 46 to 83 years; mean 69 years) with acute ischemic heart disease, plasma Interleukin-6 (IL-6) levels were measured every 3 hrs for 24 hrs using enzyme-linked immunosorbent assays. Patients of group 1 (n=10) had unstable angina pectoris (UAP) with elevated serum creatine kinase (CK) less than twice the normal value. Patients of group 2 (n=10) had UAP without elevaed CK levels. Patients of group 3 (n=10) had acute myocardial infarction.

The peak IL-6 levels and the Σ₂₄IL-6 levels in group 1 were significantly higher than those in group 2 and 3 (both p ＜0.01). The time of peak IL-6 levels in group 1 and 2 were significantly earlier than that in group 3 (both p＜0.001). A significant correlation (r=0.61) was found between the peak IL-6 levels and the peak CK levels in patients with UAP.

We infer that IL-6 produced in the more severely ischemic area and secreted into the systemic circulatory system, could affect progression of myocardial injury.