HLA-D AND T-LYMPHOCYTE REACTIVITY TO SPECIFIC PERIODONTAL PATHOGENS IN TYPE-1 DIABETIC PERIODONTITIS

BACTERIAL ANTIGEN FRAGMENTS complexed with class II major histocompati bility molecules (HLA-D) on antigen presenting cells (APCs) stimulate CD4+ T lymphocyte proliferation, presumably to protect the host. This study examined these responses to antigens of two periodontal pathogen s in four groups (n = 15) of age- (young adult) and sex-matched Caucas ian subjects with or without type 1 diabetes and moderate to severe pe riodontitis: Group DP = diabetics with periodontitis; Group DnP = diab etics without periodontitis; Group nDP = nondiabetics with periodontit is; and Group nDnP = nondiabetics without periodontitis. HLA-D phenoty pes for each subject were determined by lymphocytotoxicity assays. T l ymphocytes purified from peripheral blood were stimulated in cell cult ure with APC pulsed with various concentrations of tetanus toroid, Por phyromonas gingivalis, and Capnocytophaga sputigena antigens. T lympho cyte reactivity (H-3 thymidine incorporation) was numerically lower in cultures from diabetics stimulated with unpulsed APC (not significant ), and antigen-pulsed cultures showed low proliferation and no signifi cant differences among groups. Stimulation indices in cultures from di abetic patients stimulated with P. gingivalis or C. sputigena, however , were significantly elevated at all antigen concentrations compared t o nondiabetic cultures. The occurrence of HLA-DR4 was moderately assoc iated with diabetes (P < 0.05) and highly associated with periodontiti s (P < 0.001, log-linear model for categorical variables); and HLA-DR5 3 and HLA-DQ3 were significantly associated with periodontitis (P less than or equal to 0.02). HLA-DR was crucial to lymphocyte stimulation (anti-HLA-DR blocking experiments), but the low peripheral blood T cel l reactivity to antigens of periodontal pathogens could not be linked with HLA-D type or periodontitis susceptibility. Therefore, certain HL A-D types appear to be more highly associated with periodontitis in yo ung adults than diabetic status or lymphocyte reactivity.