Increase in serum S100A1-B and S100BB during cardiac surgery arises from extracerebral sources

Background. Elevated levels of serum S100B after coronary artery bypass grafting may arise from extracerebral contamination. Serum S100B content was analyzed in several tissues, and the two dimers S100A1-B and S100BB were analyzed separately in blood. Methods. Serum, shed blood, marrow, fat, and muscle were studied in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass using suction either to the cardiotomy reservoir (group 1, N = 10) or to a cell-saving device (group 2, N = 10), or operated on off-pump (group 3, N = 10). Results. Serum S100B was sixfold higher in group 1 than in groups 2 and 3, which were identical. The same ratio between S100A1-B and S100BB was found in all groups. When compared with serum, S100B was 102 to 104 times higher in marrow, fat, muscle tissue, and shed blood. Conclusions. Separate analysis of S100A1-B and S100BB did not distinguish between S100B of cerebral and extracerebral origin. The concept that S100B only originates in astroglial and Schwann cells is wrong. Fat, muscle, and marrow in mediastinal blood contain high levels of S100B. Cardiopulmonary bypass caused no increase in S100B.