Lymphocyte Function in Early-Onset Periodontitis.

This is a limited review of recent research on the role of lymphocytes in earlyonset periodontitis (EOP). EOP lesions are histologically characterized by a dense infiltrate of lymphocytes. The role of lymphocytes in these lesions is unclear, but recent evidence suggests that there may be alterations in the regulatory events that govern immune responsiveness in EOP. These alterations might contribute to increased susceptibility to disease in certain individuals. Although there are no numerical abnormalities in the proportions of T cells, T-cell subsets, or B cells in the peripheral blood of EOP subjects, there may be alterations in the T helper-T suppressor ratio within the actual lesions, and these may affect local B-cell proliferation and function. Antibody produced against the antigens of pathogenic bacteria in EOP has a prominent IgG2 component but is now believed to be primarily protective to the host. Peripheral blood mononuclear cells from EOP patients have been reported to exhibit a reduced autologous mixed lymphocyte reaction, and a higher-than-normal response to B-cell mitogens. Whether or not these phenomena are important in progression or resolution of EOP is unknown. Locally acting cytokines such as IL-4 may be elevated, and this may influence the nature of the response. Use of molecular techniques to test possible relationships between susceptibility to EOP and the lymphocyte response, such as evaluation of MHC Class II and TCR gene usage, promises to provide further clues as to the role of lymphoid cells in, and genetic nature of, these forms of periodontitis. J Periodontol 1996;67:332-336. © 1996 American Academy of Periodontology.