Levels of nitric oxide (NO) in lymph node cell (LNC) culture supernatant and serum of Celastrus-treated Lewis (LEW) rats. (a) LNC culture supernatant and (b) sera were obtained from Celastrus-fed and Water-fed rats as described in Materials and methods. The level of NO in these samples was determined by a colorimetric assay. The results are presented as μM (mean + standard error of the mean). The level of NO secreted into the culture supernate following mycobacterial hsp65 (Bhsp65) restimulation of LNCs of Celastrus-fed rats was significantly (**p < 0.005, *p < 0.05) lower than that of water-fed rats on days 16 and 24 following M. tuberculosis H37Ra (Mtb) immunization (a). The levels of NO in sera of Celastrus-fed rats was significantly (**p < 0.01, *p < 0.05) decreased at days 16 and 24 compared to those of water-fed rats (b). However, the levels of NO in sera of both these Mtb-immunized groups of rats were higher (++p < 0.01, +p < 0.05) compared to those of naïve sera. In each section, some of the error bars are too small to be detected.