Relationship of nitric oxide and protein carbonyl in tuberculosis

Tuberculosis (TB) is a highly contagious disease caused by Mycobacterium tuberculosis. The bacilli replicate within the macrophages and can remain dormant for years; activated macrophages show immunity against these bacilli.

A prospective study was carried out in newly diagnosed TB patients (n = 70) before their antituberculosis treatment and in normal control subjects (n = 35). Serum level of nitric oxide was estimated by Moshage method, 1995 and Bories and Bories method, 1995 and protein carbonyl by Levine method, 1990. Pearson's correlation (r) and Fisher's 'z' test was performed on the obtained results.

In our study, serum nitric oxide and protein carbonyl levels were significantly increased (p < 0.001) in TB patients as compared to normal control group. Positive correlation was seen in pulmonary TB (r = 0.8892, p < 0.001) [Fisher's 'z' transformed = 0.7901 to 0.9430] and extra-pulmonary TB (r = 0.8330, p < 0.001) [Fisher's 'z' transformed = 0.6918 to 0.9128]; 'r' and Fisher's 'Z' was significantly different from zero (two sided p < 0.001).

The mean serum nitric oxide and protein carbonyl levels were concomitantly increased and positively correlated with each other in patients with pulmonary TB and extra-pulmonary TB. The changes in the level of nitric oxide and protein carbonyl are a reflection of increased defence mechanism and free radical activity in tuberculosis.