HNK-1+ (Leu-7) cells and natural killer cell activity in inflamed human gingival tissue

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Abstract
The presence of HNK-1 (Leu-7)-positive cells and natural killer (NK) cell activity was determined in human periodontal tissues. Gingival tissues obtained from 25 adult patients were processed for analysis utilizing a HNK-1 (Leu-7) mouse monoclonal antibody. A subpopulation of non-adherent lymphoid cells obtained by collagenase digestion of inflamed gingival tissues from 10 patients was examined for the presence of large granular lymphocytes (LGL) by May-Grünwald-Giemsa staining and for NK cell activity against K562 cells by a 51Cr release cytotoxicity assay. HNK-1+ cells were identified in gingival tissue sections of 21 patients, and were present in or close to discrete foci of plasma cells. HNK-1+ cells were scarce in mildly inflamed or uninflamed tissues sections. LGL were identified in 9 of 10 gingival single-cell suspensions and constituted approximately 5% of the gingival cell population. NK cell-mediated cytolysis, at varying effector/target cell ratios, was observed for 3 of 4 enriched gingival mononuclear cell populations. Gamma-interferon (INF-gamma) preincubation of enriched gingival effector cells from 5 additional patients resulted in a 43% increase in NK cell activity. The finding of increased HNK-1+ cells with gingival inflammation suggests that these cells may play a role in tissue damage, as well as in modulation of B cell activity, in gingivae of patients with periodontal disease.