A couple of markers to consider could be CD62L and CD11b. I've measured these in a previous study to assess leukocyte (neutrophil and monocyte) activation following orthopaedic surgery.
Hope this helps, ref:
Hughes SF, Hendricks BD, Edwards DR, & Middleton JF, (2010). Tourniquet-applied upper limb orthopaedic surgery results in increased inflammation and changes to leukocyte, coagulation & endothelial markers. PLOS ONE 5(7): e11846. doi:10.1371/journal.pone.0011846.
after 6 hours, most macrophage markers start to downregulate, inlcuding CD80, 86 and CD 11c. Their peak of expression is at 6 hours. After that apoptosis is likely to occur for cells expressing CD80, 86 and 11c. Other macrophages should be then expressing CD206 and 163.
Activated monocytes should express higher level of MHC: difference may not be seen at regular flow but could be of value if you are able to measure the density of expression. Thuis, u will get marker and activation measure in one.