Nitric oxide in cerebrospinal fluid of central nervous system tuberculosis: correlations with culture, antibody response, and cell count

The role of nitric oxide (NO) has been established in infection over the years. NO functions by inhibiting the growth of intracellular pathogens. The present study was undertaken to ascertain the role of NO in central nervous system (CNS) infection by Mycobacterium tuberculosis. A total of 781 chronic meningitis cerebrospinal fluid (CSF) samples suspected of CNS tuberculosis (TB) were categorized based on M. tuberculosis culture positivity, anti-TB antibody response, and CSF cell count and were analyzed for NO. We found that NO levels were positive in 10.88% of the CSF samples. Positivity for NO was 18%, 11.67%, 13.68%, 9.32%, and 9.66% in the cases with mycobacterial culture positivity, anti-TB antibody positivity, high cell count, low cell count, and zero cell count, respectively. Among the above cell count categories, NO levels were noticed to be elevated in high cell count samples with mononuclear cell predominance. This study suggests that NO might play some role in the later stages of tuberculous meningitis. This is the first study to our knowledge in which NO was evaluated in CSF in relation to immune response and the presence of a pathogen with such a large number of subjects.