Fluorescence Quantitation of S-IgA in Parotid Saliva and of S-IgA Bound to Oral Microorganisms

Quantitation of secretory IgA (s-IgA) in parotid saliva (1), whole saliva (2,3) and in other exocrine secretions (4) is generally performed by radial immunodiffusion. Although simple and quantitative, this method does not readily lend itself to the determination of s-IgA bound to oral microorganisms. Two techniques quantitating the binding of parotid salivary s-IgA to Streptococcus mutans, a modified ELISA assay (5) and an agglutinin assay (6), have recently been published. The aim of the present work was to develop fluorescence methods to quantitate the concentration of s-IgA in parotid saliva and the percentage of parotid s-IgA bound to a specific oral microorganism. Fluorescence assays have the advantage of high sensitivity and moreover permit direct visualization of binding by fluorescence microscopy.