Ultrastructural evidence of large granular lymphocyte (LGL) activity in lesions of chronic adult periodontitis.

The purpose of this investigation was to determine, on the basis of ultrastructural evidence, whether large granular lymphocyte (LGL)-mediated cytotoxic activity could be identified in lesions of chronic adult periodontitis. 18 gingival papilla biopsies were obtained from 8 adult patients, each satisfying the clinical criteria for chronic adult periodontitis. One-half of each biopsy was processed for examination by transmission electron microscopy (TEM). B-lymphocyte, T-lymphocyte, and NK-cell contributions to the inflammatory cell infiltrate were determined by subjecting the remaining one-half to the 3-layer avidin-biotin affinity immunoperoxidase technique. Immunohistochemistry using the anti-human leu-11b monoclonal antibody (representative of NK-cells which are known to comprise approximately 80% of the LGL population) showed that the Leu-11b+ population comprised 3-7% of the total monocytic infiltrate. The Leu-11b+ cells tended to occur as single cells or in small clusters of 3-12 cells. Generally, the Leu-11b+ cells exhibited perivascular locations situated subjacent to the epithelial basal lamina. TEM observations showed LGLs in intimate contact with fibroblasts that exhibited morphologic changes consistent with cellular damage or degeneration. In addition, LGLs were observed to exhibit apparent non-cytotoxic contacts with plasma cells, macrophages and other monocytic cells.