Impact of the inflammatory response on specific immunity in neurosurgical patients

Abstract: Vaccination with a T-cell-dependent pneumococcal conjugate vaccine (PCV) followed by a T-cell-independent pneumococcal polysaccharide vaccine (PPSV) is recommended after basilar skull fracture to reduce the risk of meningitis. The optimal time frame for vaccination has not yet been established and varies widely in practice. Because the risk of meningitis is at its peak shortly after the trauma incident, early vaccination might be more desirable. After trauma and central nervous system (CNS) injury, T-cell defects leading to trauma and CNS injury-induced immune deficiency syndromes may affect the vaccine response. In light of the above information, the overall aim of this thesis was to investigate the impact of neurotrauma and neurosurgery on the response to T-cell-dependent and T-cell-independent vaccines.In Paper I, we compared the antibody response to a T-cell-dependent conjugate vaccine in patients vaccinated within 10 days after neurotrauma or neurosurgery with those vaccinated after >3 weeks. To avoid interference with pneumococcal vaccination, a conjugate vaccine against Haemophilus influenzae type b (Hib) was chosen for the study. The majority of the patients responded to the vaccination, although the number of responders was significantly lower in patients vaccinated early.In Paper II, we investigated the antibody response to the T-cell-independent vaccine PPSV in patients vaccinated within 10 days after neurotrauma or neurosurgery and in patients vaccinated after >3 weeks. Patients vaccinated early responded similarly to those vaccinated after the acute period, indicating that PPSV can be administered early after neurotrauma or neurosurgery.In Paper III, we compared the response to Hib vaccine with the response to PPSV. We also examined whether individual clinical or immunological parameters might predict the response to T-cell-dependent vaccine and thereby help identify non-responders before vaccination. No correlation between Hib vaccine and PPSV responses was found, indicating that B-cell function is not similarly depressed as T-cell function. It was not possible to predict the T-cell-dependent vaccine response by standardized grading of the trauma or by parameters reflecting the innate immune response.In Paper IV, we found a significant reduction in the ex vivo CD4+ T-lymphocyte response to PCV in patients after neurotrauma or neurosurgery as compared with healthy controls.Our results suggest that PPSV might be a viable alternative to T-cell-dependent PCV in early vaccination after neurotrauma.