The kinetics of murine peritoneal macrophage replication.

The percentage of peritoneal macrophages synthesising DNA in the unstimulated mouse peritoneum was found to be 0.4 per cent. after a 30 min in-vivo pulse label of 3H Tdr. This percentage was found to rise to 4.0, 24 hr after stimulation of the cavity with thioglycollate. Using BrdU incorporation as an indicator of DNA synthesis it was found that in the unstimulated animals S + G2 lasted 12-15 hr while the same functions in stimulated animals took 7-10 hr. A small proportion of much more rapidly dividing cells was found in both stimulated an unstimulated animals. These findings possibly reflect differences between resident and exudate macrophages, or alterations in the kinetics of macrophage division as a result of inflammation. It was concluded that as the increase in the number of cells synthesising DNA and their rate of division was too low, the increase in the number of cells in the stimulated cavity could not be solely the result of cell division within the cavity.