Interleukin-1 receptor antagonist: a sensitive marker of instability in patients with coronary artery disease

Increased plasma levels of acute phase reactants are correlated with acute coronary syndromes and increased risk of in-hospital events. Interleukin-1 receptor antagonist (IL-1Ra) modulates the activity of IL-1, a cytokine associated with inflammatory response; we have prospectively investigated whether detection of increased levels of IL-1Ra in patients may be useful in the characterization of coronary syndromes.

Plasma levels of IL-1Ra were measured in 118 consecutive patients undergoing coronary angiography with a clinical diagnosis of recent unstable angina (N = 57), chronic stable angina (N = 49) or atypical chest pain (N = 12).

Angiography showed significant coronary disease in the first two groups and was normal in the latter group. Patients with unstable angina had significantly higher levels of IL-1Ra than stable patients [158 (110-224) vs 108 (95-154) pg/ml, P = 0.002] and individuals with chest pain and normal coronary angiogram [110 (97-123) pg/ml, P: = 0.038]. In contrast, while C-reactive protein levels were significantly higher in patients with stable and unstable angina vs those without coronary disease (0.29 vs 0.06 mg/dl, P: = 0.022), they did not discriminate between stable and unstable angina patients (0.22 vs 0.32 mg/dl, P: = 0.66).

These results indicate that IL-1Ra may be a sensitive marker of clinical instability in patients with coronary artery disease.