Immunochemical identification and determination of proline-rich proteins in salivary secretions, enamel pellicle, and glandular tissue specimens. 
Acidic proline-rich proteins were localized histologically by means of the indirect immunoperoxidase technique in the acinar cells of parotid and submandibular gland sections of both man and Macaca fascicularis.  These proteins were also identified as constituents of the long term in vivo-formed acquired pellicle on human tooth surfaces employing the same immunoperoxidase technique.  Immunological quantitation of proline-rich proteins in whole and parotid saliva of 42 subjects indicates the presence of high concentrations in parotid secretions varying between 19-80 mg%, while their levels in whole saliva are significantly lower, ranging between 0-18 mg%.  The concentrations of these proteins in whole saliva exhibited a negative correlation with plaque accumulation (r = -0.464) and gingival index scores (r = -0.576).