Nitric oxide production by BCG-infected pleural macrophages from C57B1/6 and DBA-2 mice

We studied the kinetics of in vivo nitrite production in the inflammatory r eaction induced by M. bovis BCG into the pleural space. Pleural macrophages harvested from C57B1/6 mice after acute BCG infection produced high levels of nitric oxide (NO). Enhanced production was obtained upon stimulation wi th LPS plus IFN-gamma. In sharp contrast, macrophages from DBA-2 mice produ ced low levels of NO, as nitrite, at the same time interval (24 h after BCG infection), being completely refractory to further stimulation. After the third day, NO production was similar in both strains. There was a close rel ationship between nitrite levels in the pleural exudate in vivo and those p roduced by harvested macrophages in vitro. In this in vivo system, the patt ern of NO production by pleural macrophages one day after BCG infection was discrepant and unexpected in the response of C57B1/6 and DBA-2 mice. Howev er, this early response did not affect the late progressive NO production i n both mice strains, that may be responsible to the late control of the myc obacteria growth.