Heterogeneity of host immunological risk factors in patients with aggressive periodontitis

Background: The pathogenesis of early-onset periodontitis (EOP) can be expl ained by various host risk factors. Previous studies have focused on a sing le (among many possible) immunological risk factor and the association amon g the factors has not been assessed. We comprehensively investigated the as sociations among multiple host immunological risk factors in EOP patients t o further elucidate their role in the pathogenesis of EOP. Methods: Sixty-eight EOP patients (50 generalized EOP, 18 localized EOP), 5 1 EOP-suspected patients (S-EOP), 43 adult periodontitis (AP) patients, and 36 periodontally healthy subjects (HS) participated in this cross-sectiona l study. We examined peripheral neutrophil functions, phenotypic and functi onal characterization of peripheral lymphocytes (lymphocyte subsets, T-cell proliferative activity), cytokine productivity (interleukin [IL]-1, IL-2, tumor necrosis factor [TNF]-alpha, interferon [IFN]-gamma, IL-4 and IL-6), serum immunoglobulin G (IgG) antibody titers against 12 periodontal bacteri a, and HLA class II genotypes. Results: G-EOP, S-EOP, and AP patient groups showed significantly lower per centages of pan T cells and CD8-positive cells (P<0.02) compared with the H S group. L-EOP patients showed depressed IL-4 and TNF-<alpha> productivity compared with the HS group (P <0.02). The EOP group showed significantly el evated antibody levels against Actinobacillus actinomycetemcomitans, Porphy romonas gingivalis, Treponema denticola, and Fusobacterium nucleatum compar ed with the HS group (P <0.05). The frequency with DQB1*0503 was significan tly higher in the EOP patient group than the HS group (P = 0.045) due to th e higher frequency in L-EOP patients than the HS group (P = 0.035). There w ere wide interindividual variations in each of the tests among patient and HS groups; however, EOP patients showed wider intradiagnostic group variati ons in certain host defensive cell functions than the other groups. There w ere some EOP patients who showed extremely low or high values in some tests ; the EOP patients could be further divided into subgroups according to the ir host defensive and immunological profiles. However, there was heterogene ity in some of the other host immunological tests even in the subgroups. Conclusions: The association of host immunological risk factors in EOP pati ents is widely varied and more complex than previously thought. These resul ts indicate the difficulty of explaining the pathogenesis of EOP based on a single host risk factor and also emphasize the importance of critical asse ssment of not only EOP patient groups, but also individual patients.