Objective: The aim of this study was to determine the relation of plasma interleukin-12 (IL-12) concentration to major risk factors of atherosclerosis and other personal characteristics in well-documented, stable ischaemic heart disease (IHD) patients. The hypothesis was that IL-12 is positively associated with inflammatory markers and risk factors of atherosclerosis.
Materials and methods: Clinical data were collected from 51 IHD patients by a questionnaire and from basic laboratory blood tests. The association of IL-12 with the biochemical, personal, health status and lifestyle determinants was investigated by regression analysis and analysis of variance.
Results: Plasma IL-12 concentration was associated inversely with the plasma concentration of triglycerides (P=0.001) and homocysteine (P=0.04). However, IL-12 was associated directly with the concentration of high-density lipoprotein cholesterol (P=0.03). IL-12 concentration was not strongly associated with other biochemical parameters nor with the health status, medication or lifestyle determinants.
Conclusion: The results suggest that, contrary to the hypothesis, IL-12 was associated inversely with plasma levels of two known risk factors of coronary atherosclerosis (triglycerides, homocysteine) in stable, statin-medicated IHD patients. The lack of association of IL-12 with high-sensitivity C-reactive protein, erythrocyte sedimentation rate and the number of inflammatory cells in blood suggests that moderately elevated IL-12 did not imply ongoing systemic inflammation in these patients. Although increased IL-12 production is a sign of proinflammatory activity, it was associated directly with the plasma high-density lipoprotein cholesterol concentration. Overall, moderately elevated plasma IL-12 concentration may even be a good sign in stable IHD patients.