521 LETTER TO THE EDITOR Do Baseline IL-6 Levels Predict Post-operative Morbidity After Surgery (CABG) in Cardiac Patients? Chandrashekara S, M.D., ∗ Chalam Mahadevan, M.Ch., ∗ Nisha Thomas, ∗ K.C. Vasantaha kumar, ∗ N.V. Shivanand, M.D., ∗ Vikram K. Yeragani, M.D. ∗ ,†,‡ ∗ Departments of Immunology, Cardiothoracic Surgery and Anesthesiology, M.S. Ramaiah Memorial Hospital, Bangalore, India; †Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan; and ‡Department of Psychiatry, University of Alberta, Edmonton, Canada Dear Editor, Cytokines are a group of proteins, which include the interleukins (IL) and interferons. They are pro- duced from activated leucocytes, fibroblast, and en- dothelial cells as an early response to tissue injury and play a major role in mediating immunity and in- flammation response. The cytokines act on the sur- face receptors of many different target cells and in- fluence protein synthesis. The initial reaction is the re- lease of IL-1 (interleukin-1) and TNF-α (tumor necrosis factor-alpha) from activated macrophages and mono- cytes in the damaged tissues. This stimulates the pro- duction and release of more cytokines; in particular, IL-6 (interleukin-6), which is responsible for inducing the systemic changes, known as the acute phase re- sponse. 1 Pro-inflammatory cytokines such as TNF-α and IL-6 are released in to the circulation in response to cardiac surgery, which may play an important role in the pathogenesis of myocardial dysfunction in ischemia reperfusion injury. 2 The complications following CABG have been attributed to the altered cytokine response, following cardiopulmonary bypass. 3 Studies in patients with sepsis and cancer surgery have shown baseline serum IL-6 to be an important predictor of outcome in these life-threatening situations. 4,5 The aim of this study was to analyze the role of IL-6 in predicting the outcome in patients after CABG surgery. We obtained IL-6 values before a patient underwent surgery and three times later to investigate if any of these measures will be positively associated with treat- ment response. There were eight males (age: 43 to 74 years) and one female (age: 62 years) who were in- cluded in this study. The surgeon, who operated on these patients taking several parameters into account, Address for correspondence: V. K. Yeragani, M.D., Flat No 103, Em- bassy Orchid, 8 Main, RMV Extension, Sadashiva Nagar, Bangalore- 560080, India. Fax: 011-91-80-23610508; e-mail: vikramyershr@ yahoo.com graded treatment-response globally. The surgeon was blind to the values of IL-6. The immunological measures were also obtained without any knowledge of the pa- tients’ condition. We used one-way repeated measures ANOVA to compare all four measures of IL-6 over time. There was a highly significant increase in these values over time (F = 33.3; df = 3,27; p = 0.00001; 0.08 ± 0.04; 0.24 ± 0.35; 0.37 ± 0.46; and 1.4 ± 0.61 (pg/mL), respec- tively). We also correlated the values of IL-6 at all four time points with treatment response. The baseline val- ues of IL-6 (before surgery) correlated significantly with the outcome after surgery (r = 0.76; df = 9; p = 0.01) (Fig. 1). Results remained the same even after the fe- male patient was excluded from the analysis. Pearson’s product moment or Spearman’s rank order correlation coefficients were almost identical. This preliminary finding suggests a possible marker for the prognosis of patients undergoing CABG and 0 2 4 6 8 Treatment Response (1: Good---6: Mortality) 0 0.04 0.08 0.12 0.16 I L - 6 ( p g / m l ) r=0.76; p=0.01 Figure 1. Relationship Between Treatment Response and IL-6 Levels.