HLA genetics for diagnosis of susceptibility to early-onset periodontitis

Human leukocyte antigens (HLA) are essential in the recognition of foreign antigens in humoral immune response, which is genetically predetermined. Su sceptibility to certain diseases that involve the immune response has been studied in relation to distinct HLA types. Although some diseases have been found Co correlate to specific HLA loci positively, it has been difficult to isolate HLA types that predispose patients to periodontal destruction. H ere. we review the current knowledge and recent advances in HLA genetics an d its biology, which determine susceptibility to early-onset periodontitis (EOP). The HLA-DRB1*1501-DQB1*0602 genotype has been found with increasing frequency in EOP patients. This HLA genotype expresses aspartic acid at pos ition 57 and glycine at position 70 on the DQ beta chain, suggesting a capa bility to bind certain bacterial antigens. The T cell response against the outer membrane protein (Ag53) of Porphyromonas against gingivalis was exami ned via this HLA genotype. Strong T cell response against Ag53 p141-161 was inhibited partially by anti-DR antibody, but not by anti-DQ antibody, poss ible host and bacterial peptides capable of binding DRB1*1501 were elucidat ed when the peptide sequence was compared to gene and protein databases. Th ese results suggest that patients who have the HLA-DRB1*1501-DQB1*0602 geno type may have an accelerated T cell response to certain periodontapathic ba cteria such as P. gingivalis in hyperimmune reactions and thus increased su sceptibility to EOP.