Background & objective: Three categories of prognostic markers are best documented as having significance in relation to prognosis of HIV infection. These include HIV viral load, CD4 T-cell levels and plasma levels of soluble markers of immune activation. The plasma activation markers, like neopterin, tumor necrosis factor alpha (TNF-alpha), interleukins etc., are products of cytokine activity and represent immunologic changes throughout the body. There is not much information available on serum neopterin estimation in patients infected with both HIV and tuberculosis (TB), though neopterin levels are known to be elevated in pulmonary TB patients. In this study we attempted to correlate neopterin levels with the presence of tuberculosis in HIV infected and uninfected individuals and studied the changes after antituberculosis treatment.

Methods: Serum neopterin concentrations were measured by high performance liquid chromatography (HPLC) in 25 HIV-seropositive (HIV-TB) and 10-seronegative (TB) patients with tuberculosis before, during and at the end of antituberculosis therapy (ATT). S-neo was also measured in 10 HIV-seropositive asymptomatic individuals and 10 healthy controls. The results were correlated with clinical, bacteriological and immunological status.

Results: All TB patients regardless of HIV status had elevated s-neo concentrations at diagnosis, which declined gradually during treatment. Patients with HIV/TB with CD4 counts < 200/mm(3) had the highest levels at baseline with a steep fall during treatment. The median level at the end of treatment was significantly higher in HIV/TB than in TB patients, despite clinical improvement and bacteriological clearance of Mycobacterium tuberculosis. HIV infected asymptomatic individuals had neopterin levels that were higher than healthy controls but lower than HIV-TB patients.

Interpretation & conclusion: Serum neopterin levels are elevated in HIV-positive patients, with the highest levels in those with tuberculosis and CD4 counts < 200/mm(3). Though the levels decrease with anti tuberculosis therapy, persistently elevated levels indicate progressive HIV disease and a poor prognosis.