QUANTITATIVE ASSESSMENT OF MAST-CELLS IN RECURRENT APHTHOUS ULCERS (RAU)

Previous studies on the frequency of mast cells (MCs) in recurrent aph thous ulcers (RAU) have yielded conflicting results, Monoclonal antibo dies specific for tryptase (AAI) and anti-IgE (polyclonal antibody) we re used to identify density and distribution of MCs in an immunohistoc hemical study of RAU (n=15), induced oral traumatic ulcers (TUs) (n=9) , and control clinically healthy oral mucosa (n=15), Results were quan tified by means of a VIDAS image analyzer. In all sections studied, Ig E-positive cells showed similar frequency and distribution to tryptase -positive MCs. In RAU lesions, numerous tryptase-positive MCs were fou nd in the sub-epithelial lamina propria but MC numbers in the epitheli um were low and present only in some RAU biopsies. MCs were also more numerous in RAU-inflammatory infiltrates (118+/-31 cells/mm(2)) than t hose seen in TU-inflammatory infiltrates (75+/-18 cells/mm(2), P<0.001 ). MC activation/degranulation, as judged by diffuse extracellular try ptase staining, was a common feature within RAU-inflammatory infiltrat es and at RAU-inflammatory infiltrates-connective tissue interfaces, w hich were often associated with connective tissue disruption. MC count s in the RAU connective tissue, lateral to the inflammatory infiltrate s, were significantly greater than in the connective tissue of TUs and of control biopsies (124+/-36 us 75+/-13 vs 69+/-21 cells/mm(2), resp ectively; P<0.001). Overall, MCs were significantly increased in aphth ae (116+/-26 cells/ mm(2)) compared with TU lesions (72+/-11 cells/mm( 2), P<0.001) and controls (71+/-16 cells/mm(2), P<0.001). In conclusio n, MC numbers are increased in a typical topographical pattern, and th e local MCs show signs of activation/degranulation suggesting active i nvolvement of this cell type in RAU pathogenesis.