Immunoglobulins of human dental plaque

Abstract

Pooled supragingival dental plaque was extracted with phosphate-buffered saline solution (PSS) at pH 7.5, followed by glycine-HCl buffer at pH 2.3. IgA, IgG and albumin (HSA) were detected, with specific antiserums, in both types of plaque extracts. IgM was not detected. IgG concentration, relative to IgA, was greater than in whole saliva, suggesting that IgG could be derived primarily from gingival crevice fluid. IgA was the major immunoglobulin recovered, representing 1.6–2.7 per cent of the total extracted protein. Most of the IgA in the PSS extract eluted at, or near, the void volume of a Sephadex G-200 column, and reacted with antiserum directed to the secretory component, indicating that this immunoglobulin was primarily an intact secretory IgA molecule. Most of the IgG appeared to be degraded to a fragment of approximately 24,000 molecular weight bearing Fc antigenic determinants. Some degraded IgA was detected which had a molecular weight of approximately 105,000, and could correspond to a F (ab′) 2α fragment. HSA did not seem to be degraded.