Increase of RM3/1-positive macrophages in radiation-induced oral mucositis

The purpose of this study was to describe the distribution patterns of vari ous leukocyte subpopulations in the oral mucosa during the course of radiot herapy and to determine whether there are dose-dependent alterations, or an y correlation between the clinical stages and the population density of spe cific leukocytes, The distribution and density of various leukocytes in ora l mucosa in 13 head and neck cancer patients were immunohistochemically ana lysed before radiotherapy at 30 and 60 Gy and compared with the clinical de gree of oral mucositis, Antibodies were used which characterized different subtypes of macrophages (27E10, 25F9, RM3/1) and recognized epitopes of gra nulocytes (CD15) and T cells (CD3, CD4, CD8), The study showed that whereas macrophages reactive with RM3/1 increased significantly at 30 Gy (p < 0.01 ) and showed a further increase at 60 Gy (p < 0.01), no significant alterat ions could be detected in the density of macrophages which stained positive ly for 27E10 or 25F9. Moreover, the percentage of macrophages reactive with RM3/1 showed a non-linear correlation with the clinical mucositis score (p < 0.05), No significant alterations were detected in the percentage of T c ells and granulocytes, compared with the values before radiotherapy. In con clusion, radiation-induced mucositis is characterized by features of an int ermediate stage of an inflammatory response, suggesting active involvement of down-regulatory macrophages in its pathogenesis, Copyright (C) 2000 John Wiley & Sons, Ltd.