Some aspects of the humoral and neutrophil functions in post-comatose nawareness patients

Post-comatose unawareness (PCU) is one of the possible outcomes of severe brain injury. Patients with severe brain injury have an increased susceptibility to severe nosocomial infections for multifactorial reasons, including immune suppression at different levels. We studied different immunological aspects in 11 PCU patients. Impaired humoral immunity was found in 27% of them. Two patients had decreased haemolytic activity of the classical complement pathway, associated with decreased levels of the components C1q, C1r and C4. Another patient had very low levels of IgG2 and IgG4. The neutrophil killing activity was impaired in these three patients, but was completely restored with the addition of a heterologous serum, suggesting a humoral defect. Neutrophils showed normal chemotaxis and random migration, and the superoxide anion release by neutrophils was also found to be normal. Understanding the immunological events in PCU patients contributes to a better and more intensive therapeutic approach, which might accelerate the rehabilitation of these patients.