In situ characterization of cell infiltrates in human dental periapical granulomas 3. Demonstration of T lymphocytes

Cryostat sections of 66 snap-frozen dental periapical granulomas were examined for T lymphocytes by the closed chamber hemadsorption technique using sheep erythrocytes (E) treated with 2-aminoethylisothiouronium bromide hydrobromide (AET) as indicator cells (AET-E). T lymphocytes were also demonstrated by immunofluorescent staining using a rabbit anti-T lymphocyte antiserum. Eighty-six % of the granulomas showed adherence of AET-E, and often a focal AET-E adherence pattern was seen, indicating a localized infiltration of T lymphocytes. Diffuse, moderate binding of AET-E to sections of some granulomas may be due to recirculating T lymphocytes traversing the tissue. The results of the immunofluorescence test parallelled the results obtained in the hemadsorption test. The results show that mononuclear cell infiltrates of periapical dental granulomas usually contain T lymphocytes. Although their pathogenetic function in dental periapical granulomas is still not known, infiltrates of T lymphocytes indicate that cellular immune reactions are involved.