IMPAIRED PHAGOCYTOSIS OF STAPHYLOCOCCUS-AUREUS IN COMPLETE TETRAPLEGICS

Accumulating evidence implicates the sympathetic nervous system as a m odulator of immune function. Immune alteration has been observed in su rvivors of cervical level spinal cord injury, possibly because of dysr egulation of the sympathetic outflow tracts. The majority of immune st udies in the spinal cord-injured population have focused on lymphocyte s. Because of the high incidence of infections in this population, we hypothesized that the immune alteration would extend to the cells of t he myeloid lineage. This hypothesis was tested by analyzing the phagoc ytic and bactericidal function of circulating neutrophils in response to Staphylococcus aureus. A group of ten individuals with complete cer vical spinal cord injury, a group of eight paraplegics with injuries b elow the majority of sympathetic outflow (T-10 and below), and age-and gender-matched controls for each subject were studied, In addition, a psychiatric screening for depression was completed by all subjects an d controls. Paired t test revealed significantly impaired phagocytic a bility in the tetraplegic group compared with their controls. The para plegic group did not demonstrate these findings. Our results suggest t hat individuals who have sustained complete cervical spinal cord injur y have alteration in immune function compared with neurologically inta ct controls, whereas those with lesions at or below T-10 do not. This in vitro finding may be related to infection after cervical spinal cor d injury. The mechanism may involve dysregulation of the sympathetic a rm of the autonomic nervous system.