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Subpopulations of lymphocytes in connective tissue from phenytoin-induced gingival overgrowth
Insights
Phenytoin (PHT) gingival overgrowth in children involves significant T-lymphocyte infiltration. These findings suggest T-cell mediated immune responses contribute to PHT-induced gingival lesions.
Area of Science:
- Immunology
- Oral Pathology
- Pharmacology
Background:
- Phenytoin (PHT) is a medication known to cause gingival overgrowth.
- The cellular mechanisms underlying PHT-induced gingival overgrowth are not fully understood.
- Gingival inflammation and overgrowth can significantly impact oral health.
Purpose of the Study:
- To investigate the types and distribution of mononuclear cells in gingival biopsies from children with PHT-induced gingival overgrowth.
- To compare the cellular infiltrate in PHT-induced gingival overgrowth with gingivitis and healthy controls.
- To explore the potential role of T-lymphocytes in the pathogenesis of PHT-induced gingival overgrowth.
Main Methods:
- Gingival biopsies were obtained from children with PHT-induced gingival overgrowth, gingivitis, and healthy controls.
- Mononuclear cells were identified using monoclonal antibodies against T-lymphocyte subpopulations (T-helper, T-suppressor/cytotoxic), B-lymphocytes, and monocytes.
- Immunohistochemistry was employed to detect HLA-DR expression on mononuclear cells.
Main Results:
- Biopsies from children with PHT-induced gingival overgrowth showed a substantial increase in mononuclear cells, predominantly T-lymphocytes.
- A high percentage of T-lymphocytes expressed T-helper (OKT4+) and T-suppressor/cytotoxic (OKT8+) phenotypes.
- The majority of mononuclear cells in PHT-induced lesions expressed HLA-DR, indicating immune activation.
- Control and gingivitis groups had fewer mononuclear cells, mainly T-cells, with minimal HLA-DR expression.
Conclusions:
- T-lymphocytes, particularly activated T-cells expressing HLA-DR, are significantly involved in the pathogenesis of phenytoin-induced gingival overgrowth.
- The findings suggest an immunologic basis for PHT-induced gingival lesions.
- Further research into T-cell mediated mechanisms could inform therapeutic strategies.
Abstract:
The presence of mononuclear cells was studied in gingival biopsies from seven children exhibiting phenytoin(PHT)-induced gingival overgrowth, three children with gingivitis and a control group consisting of three children without clinical signs of inflammation. The mononuclear cells were detected using monoclonal antibodies defining functional T-lymphocyte subpopulations, B-lymphocytes and monocytes. Gingival biopsies from the individuals in the PHT-group showed a substantial number of mononuclear cells. The distribution of mononuclear cells in separate individuals were as follows: 69-95% OKT3 +/Leu4+ cells (T-lymphocytes), 50-64% OKT4 +/Leu3+ cells (T-helper phenotype) and 29-46% OKT8+ cells (T-suppressor/cytotoxic phenotype). None of the biopsies in the PHT-group contained more than a few scattered plasma cells. The vast majority of all mononuclear cells present in the biopsies reacted with OKIa1, a monoclonal antibody defining the HLA-DR framework. In contrast, biopsies from the control group and the gingivitis group contained few mononuclear cells, the majority of which were T-cells. This suggests that immunologic reactions mediated by T-cells may play a role in the pathogenesis of the PHT-induced lesion.