ALTERATION IN THE PATTERN OF MACROPHAGE SUBTYPES IN CHRONIC OSTEOMYELITIS COMPARED WITH ACUTE JOINT INFECTION

Macrophage subtypes were detected in cryostat sections of biopsies fro m patients with chronic osteomyelitis, acute joint infections and norm al bone marrow, using monoclonal antibodies against different macropha ge populations. The resident macrophage subtype 25F9, the glucocortico id-inducible macrophage RM 3/1 and the inflammatory type 27E10 were fo und in abundance in acute infections. They were also present in tissue sections of uninflamed bone marrow. By contrast, in about 50% of the biopsies front patients with chronic osteomyelitis a reduced number of macrophage subtypes, or even the lack of one or more macrophage subpo pulations was found The unusual absence of macrophage phenotypes seems to be restricted to the area of osteomyelitis because in the tissues of inflamed sinuses in these patients, the macrophage subtypes were pr esent. These findings suggest a disturbance at the level of the macrop hages which may contribute to the persistence of the inflammatory proc ess in osteomyelitis.