The Immune System

The immune system is under the control of the CNS. Even if the immune system is intact, its response to stimulation is modified considerably after total and irreversible loss of CNS functions. Increased levels of cytokines in blood and in organs are observed in brain-dead patients, and it is thought that these cytokines are responsible for some of the endocrine and acute-phase reactant abnormalities found in these patients and for the low success rates after organ transplantation. Amado and associates^[59] investigated blood levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in brain-dead patients and reported that although IL-1 and TNF levels were within the normal range, IL-6 levels were clearly above the normal range in all patients. Lopau and colleagues^[60] found a significant correlation with rises in IL-6 and soluble TNF and IL-2 receptors as markers for the activation of immunologic cascades in brain-dead patients. Plenz and associates^[61] reported that IL-6, IL-6 receptor, and the common signal transducer of the IL-6 family, glycoprotein 130 (gp130), were strongly expressed in all hearts of brain-dead patients.