Development of a rapid qualitative assay for determining elevated antibody levels to periodontopathic organisms

To allow more widespread use of systemic antibody analysis in clinical settings, a rapid test for determining elevated antibody to periodontitis-associated bacteria was developed. The technique utilizes dot-immunoblotting (DIB) on nitrocellulose paper with whole formalinized Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia. An ELISA was used to compare IgG antibody levels to these organisms in venous serum and peripheral capillary blood from 44 subjects. Correlation between serum and capillary levels ranged from r = 0.760 to 0.900 (P less than 0.00001). Capillary blood antibody levels averaged 55% of those detected in serum. The assay was developed using a variety of antigen and reagent concentrations and multiple chromogenic enzyme-substrate systems. Subsequently, 34 periodontally diseased and 10 periodontally healthy subjects were analyzed for serum IgG antibodies using a quantitative ELISA. The qualitative DIB was performed using capillary blood obtained by digi-puncture and results were compared in a blind fashion to the ELISA data. Relative to its ability to detect elevated antibody levels to these 3 organisms, the DIB had an overall sensitivity of 93% and a specificity of 87% (P less than 0.000001). Using peripheral capillary blood and the DIB, detection of elevated systemic antibody levels can be performed in approximately 2 hours. The DIB may be a useful aid in assessing the host response to putative periodontopathic microorganisms.