PATTERN OF MACROPHAGE SUBPOPULATIONS IN POSTTRAUMATIC BONE-INFECTIONSAFTER COMBINED OPERATIVE ANTIBIOTIC-TREATMENT

Macrophage subpopulations were detected immunohistochemically with the aid of monoclonal antibodies in tissue sections of 15 patients with p osttraumatic osteomyelitis at the beginning of therapy and after combi ned operative/antibiotic treatment. Macrophages represent the majority of the immunocompetent cells in osteomyelitis tissue. Before the star t of therapy, the acute inflammatory macrophage subtype 27E10 was abse nt or rarely found in 8/13 evaluable biopsies from the osteomyelitis f ocus, and a further decrease in the expression of these macrophage ant igens was observed after treatment. The RM3/1-positive macrophage asso ciated with the down-regulation of inflammation was detectable to a lo w extent in 4/13 evaluable biopsies from the osteomyelitis focus befor e the start of therapy. After treatment of the infection, an increase in this subtype was found in the cellular inflammatory infiltrates in the tissues samples examined. In 8/15 biopsies a marked expression of the RM3/1 antigen was observed. At the start of treatment, the macroph age 25F9, which dominates in the late phase of inflammation, was missi ng in 3/13 tissue samples. After combined operative/antibiotic treatme nt the 25F9-positive macrophage was found in all patients, having incr eased in 7/14 biopsies studied. These data suggest that treatment of p osttraumatic osteomyelitis leads to a local macrophage subtype distrib ution in the osteomyelitis focus resembling the pattern of a late infl ammatory reaction.