How to keep activated peritoneal macrophages from migrating?

 I'm looking to isolate as many of the peritoneal macrophages as I can. Right now I'm getting really low numbers using lavage and I need enought to be able to sort and then run expression studies.what I do is I inject a substance that i want to test into the peritoneum of WT animals and then I want to study the interaction between the activted macrophages, but the macrophages get activated and run out of the peritoneum so fast I can't catch them ):I do not want to inject anything proir to my treatment into the peritoneum because I want it to be clean.Any protocol? Any known way of blocking migration of the macrophages after my treatment? Any inhibitor for their migration?Thanks!!!!!!!