METHODS: Twenty-five adult diabetic patients and 32 non-diabetic controls (from which 20 had periodontitis and 12 were periodontally healthy) were examined. All subjects received full-mouth assessments of plaque, bleeding on probing, pocket depth and attachment level at six sites per tooth. Unstimulated whole saliva was collected from all subjects. Evaluation of salivary checkerboard immunoblotting was performed by comparing IgA levels specific for Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans of eight saliva samples with those determined by ELISA. Salivary total IgA, anti-P. gingivalis IgA and anti-A. actinomycetemcomitans IgA were measured (ng/ml) using checkerboard immunoblotting for all of the samples. Antibody secretion rate was calculated by multiplying each antibody concentration with each individual's saliva secretion rate.
RESULTS: The salivary IgA levels for both P. gingivalis and A. actinomycetemcomitans determined by checkerboard immunoblotting showed high correlations with the corresponding levels determined by ELISA, demonstrating the reliability of checkerboard immunoblotting. 20 of the NIDDM individuals tested were found to suffer from periodontitis. Salivary IgA secretion rates for A. actinomycetemcomitans were found to be significantly lower in diabetic patients compared to non-diabetic non-periodontitis controls, but similar to those in the non-diabetic group with periodontitis. The anti-P. gingivalis IgA levels were similar in all groups tested.
CONCLUSIONS: Our results demonstrate that: 1) checkerboard immunoblotting is a reliable, repeatable and high-throughput method for quantifying salivary specific antibodies. 2) Our preliminary results also indicate that individuals suffering from periodontitis (regardless of their NIDDM condition) secrete lower levels of A. actinomycetemcomitans specific IgA.