Interleukin-4 exerts anti-inflammatory effects through decreased macrophage production of tumor necrosis factor-alpha and interleukin-1 beta. We investigated genetic predisposition in the interleukin-4 response to coronary revascularization and studied the association between C-590T polymorphism, interleukin-4 levels, and outcome of surgery. DNA was obtained from 96 consecutive patients undergoing elective coronary revascularization. Patients were genotyped for interleukin-4 C-590T polymorphism using a sequence-specific primer polymerase chain reaction. Interleukin-4 levels were measured using an enzyme-linked immunosorbent assay in serum samples taken 3 hr postoperatively. The frequency of interleukin-4 C-590T genotypes CC, CT, and TT was 33.3%, 27.1%, and 39.6%, respectively. Patients with the TT genotype had significantly higher circulating levels of interleukin-4 (3.4 +/- 4.6 pg x mL(-1)) postoperatively compared to CC (2.5 +/- 0.1 pg x mL(-1)) and CT (2.7 +/- 0.5 pg x mL(-1)) genotypes. Interleukin-4 C-590T polymorphism is the main determinant of postoperative interleukin-4 levels. The TT genotype is the highest producer of interleukin-4. Neither the genotype nor the serum levels seem to play any role in recovery from coronary artery bypass surgery.