Relative avidity of serum antibodies to putative periodontopathogens in periodontal disease

ELISA was used to determine both the avidity and titre of IgG, IgA and IgM antibodies to the gram-negative anaerobe, Porphyromonas gingivalis, in twenty periodontitis patients enrolled in a longitudinal study of attachment loss and eleven non-periodontitis affected subjects. The avidity and titre of IgG antibodies to Actinobacillus Actinomycetemcomitans were also examined. A cross-sectional analysis of the longitudinal patients at baseline and non-periodontally affected controls confirmed earlier findings that IgG and IgA antibody titres to P. gingivalis were higher in periodontitis patients than in individuals who were not periodontally affected. In this cross-sectional analysis, IgG antibody avidities to P. gingivalis were not found to be significantly higher in periodontitis than in control subjects (p = 0.065). However, indications of the potential prognostic value of antibody avidity was demonstrated by the higher IgM avidities to P. gingivalis in patients who did not experience attachment loss during the three-month monitoring period than in those who did (p = 0.0005).