Neopterin as a marker for cell-mediated immunity in patients with pulmonary tuberculosis

S E T T I N G : Cell-mediated immunity (CMI) involves macrophage activation and T cell proliferation. These two parameters are compared in this study. O B J E C T I V E: To ascertain the role of neopterin as a biochemical marker for CMI in patients with pulmonary tuberculosis. D E S I G N : We measured neopterin levels in serum and the culture supernatants of peripheral blood mononuclear cells (MNC) after stimulation with purified protein derivative (PPD) in 11 patients with pulmonary tuberculosis and 10 healthy individuals. Lymphocyte proliferative response to PPD was carried out in these two groups. R E S U L T S : The mean concentration of serum neopterin was significantly higher in patients than in controls (P < 0.01). The spontaneous release of neopterin was significantly higher in culture supernatants of MNC from patients when compared with those of healthy controls (P < 0.05). Release of neopterin from MNC stimulated with PPD, however, was similar in both groups. The neopterin release and the stimulation index (SI) in lymphocyte proliferation assay were not comparable, suggesting that these two parameters do not run in parallel for measuring the status of CMI. However, serum concentration of neopterin was inversely related to the SI in a large proportion of subjects (66%). CONCLUSION: Measurement of neopterin, a soluble product of immune cells (macrophage), may provide information on the state of CMI