Serum IgG Antibody Responses to Oral Bacteria in Down's Syndrome

Down's Syndrome (DS) subjects are susceptible to infections, likely linked to altered immune functions.  In addition, these individuals exhibit a range of mental/physical disabilities that contributes to a decreased capacity to maintain good oral and general health.  Thus, DS are suggested to exhibit an increase in dental caries and periodontitis.  OBJECTIVE:  To determine the characteristics of systemic antibody responses to oral pathogens related to clinical presentation of the periodontium.  METHODS:  51 DS patients (5-27 yo) and 28 age-matched controls (CO, 7-18 yo) were evaluated for periodontal indices and serum collected for measuring IgG antibody to 14 oral bacteria.  RESULTS:  The DS patients exhibited a significantly increased (p=0.003) gingival index (GI) vs. the CO subjects, although debris, calculus, and a general oral health index did not differ. The GI was positively correlated with age in both DS and CO subjects.  The DS patients showed elevated (adjusted p<0.001) total serum IgG vs. CO; (no difference in serum IgA).  Significantly (at least p<0.05) elevated antibody was noted in DS vs CO patients to periodontopathic bacteria: Aa, Pn, En, Ec, and Fn.  No differences were noted in antibody to bacteria associated with dental caries.  Additional findings included: (i) antibody to the bacteria were positively correlated with age in DS; (ii) the level of selected antibody was correlated with periodontal indices in DS; and (iii) multiple logistic regression identified that antibody to Mm, Pn, Pi, Ec, total IgG, and a Debris index accurately classified the DS group with 96% accuracy.  CONCLUSIONS:  These results indicate an increase in gingival inflammation in DS patients, with serum IgG antibody responses to oral pathogens similar to those of adult periodontitis.  The hyper-IgG level in serum suggests a dysregulation of adaptive immune responses, reflected by responses to oral bacteria.  Supported by National Research Center of Egypt