In vitro TNF-α production and in vivo alteration of TNF-α RNA in mouse peritoneal macrophages after treatment with different bacterial derived agents

Since muramyl dipeptide (MDP) was recognized as a potent monocyte/macrophage activating agent, many MDP analogues were synthesized and tested for their ability to augment the host immune defence system against neoplasms. This study was performed to determine whether the newly synthesized desmuramyl N-acyl dipeptides LK 409 and LK 410 were also capable of affecting the immune system. For this purpose, the peritoneal macrophages were incubated in vitro with these two agents and TNF-α production was measured. In addition, the effect of LK 409 and LK 410 on TNF-α and IL-1 RNA levels in in vivo stimulated macrophages was determined by quantitative polymerase chain reaction (RT-PCR). None of the LK 409 and LK 410 concentrations tested were able to render macrophages in vitro to excrete a detectable amount of TNF-α in the supernatant fluid. However, the TNF-α and IL-1 RNA levels in macrophages of in vivo treated mice ( C57Bl 6) were increased in comparison to mock-treated mice. The results indicate that LK 409 and LK 410 are capable of inducing an increase in TNF-α and IL-1 RNA levels, yet in vitro TNF-α production remains under detectable levels (40 U/ml).