IgG rheumatoid factor in dental periapical lesions of patients with rheumatoid disease

To detect "hidden" IgG rheumatoid factor in tissues from dental periapical lesions, 26 rheumatoid and 14 control patients were examined by the direct immunofluorescence technique for binding of FITC-labelled IgG before and after pepsin digestion. Whereas free rheumatoid factor was detected in only 1 rheumatoid tissue before digestion with pepsin, this tissue as well as 8 other rheumatoid tissues strongly bound heat-aggregated IgG after the digestion procedure. Six of these 9 tissues also bound native IgG. In no control tissue was free rheumatoid factor detected and in only 1 was "hidden" rheumatoid factor revealed after pepsin digestion. Hence, presence of IgG rheumatoid factor correlated positively with the presence of rheumatoid disease, and evidence was established that certain features of rheumatoid inflammation occur in dental periapical lesions of many patients with rheumatoid disease.