Inhibitory IgG receptor as an immunoregulator and a relevant factor for periodontitis susceptibility

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FcγRIIB as an immunoregulator :The inhibitory IgG receptor, FcγRIIB was genetically examined to clarify its role as an immunoregulator. FcγRIIB nucleotide sequence was screened on genomic DNA isolated from peripheral blood of 100 healthy donors with informed consent by means of direct sequencing. We identified 5 and 2 single nucleotide substitutions in exon 4 and intron 4, respectively. Of these, 3 substitutions indicated amino acid changes, which might correspond to the potential splicing sites. However, no change of splicing in the FcγRIIB transcripts was identified with the determination of cDNA sequence. These substitutions located in the extracellular IgG binding domain might induce the structural change of FcγRIIB.FcγRIIB as a relevant factor for periodontitis susceptibilityWe have determined FcγRIIB genotypes for the exon 4 and intron 4, as well as exon 5 bi-allelic polymorphisms in 33 aggressive periodontitis (AGP) patients, 73 chronic periodontitis (CP) patients, and 71 healthy controls, with informed consent, by means of direct sequencing or polymerase chain reaction. Our results indicated a significant over-representation of the nt 775 C allele in the AGP group compared with the control group (AGP vs. Control : 17% vs. 6% ; P=0.01, Odds ratio 3.4), suggesting FcγRIIB gene to be a candidate factor associated with susceptibility to periodontitis.