IL-12 and interferon-gamma in relation to aggressive and chronic periodontitis. Background: The gene polymorphisms interferon-gamma (IFN-g) 874 T/A and interleukin-12 (IL-12) 1188 A/C have been associated with altered cytokine production. Both polymorphisms could be indicative for periodontitis because IFN-g and IL-12 are necessary for the optimal production of specific antibodies against periodontopathic bacteria. In this study we analyzed these polymorphisms in patients with generalized aggressive (AP) and generalized chronic (CP) periodontitis. Moreover, we assessed the relationship between these polymorphisms and the presence of five periodontopathic bacteria. Methods: A total of 114 unrelated German Caucasians with periodontitis (AP=67, CP=47) and 50 periodontitis-free controls were included. Gene polymorphisms were determined by PCR-SSP. Subgingival bacteria were molecular biologically analyzed using micro-Ident test. Distributions of alleles and genotypes were calculated by Chi²-Test with Yates' correction. If nResults: Considering age, gender, smoking and plaque level an increased odds ratio (OR=2.4, p=0.035) for AP was revealed for subjects with the TA genotype of IFN-g. In contrary, IFN-g AA was associated with a decreased odds ratio (OR=0.4, p=0.034) of detecting Actinobacillus actinomycetemcomitans after adjustment for age, gender, smoking, and pocket depth on the microbial test sites. Conclusion: The data suggest that IFN-g 874 TA which is known as "intermediate interferon-g producer" is a putative risk indicator for generalized aggressive periodontitis. Keywords: chronische Parodontitis, aggressive Parodontitis, Interleukin-12, Interferon-gamma, Genpolymorphismen