CHEMILUMINESCENT ASSAY OF ALKALINE-PHOSPHATASE IN HUMAN GINGIVAL CREVICULAR FLUID - INVESTIGATIONS WITH AN EXPERIMENTAL GINGIVITIS MODEL AND STUDIES ON THE SOURCE OF THE ENZYME WITHIN CREVICULAR FLUID

The purpose of this study was to investigate how levels of gingival cr evicular fluid (GCF) alkaline phosphatase (ALP) changes in relation to levels of plaque and gingival inflammation in 20 adults during a 21 d ay period of experimental gingivitis. The source of ALP within GCF was also investigated using a repeat sampling protocol; by determining en zyme levels derived from 30 putative periodontal pathogenic and non-pa thogenic species; and by examining inhibition profiles from a variety of host and bacterial ALP isoenzymes. Total 30-s GCF ALP levels increa sed significantly (p<0.002) during experimental gingivitis and precede d an increase in gingival index (GI) by approximately 7 days. Enzyme l evels correlated with GCF volume (R = 0.7; p<0.0001), but repeat sampl ing indicated that entry of ALP into the gingival crevice was independ ent of the rates of fluid flow. Only 5 of the bacterial species invest igated produced clearly detectable levels of ALP in culture supernatan ts, there were P. gingivalis (381), P. intermedia (581), P. nigrescens (8944), Dentin P. gingivalis (TW 471: clinical isolate) and C. ochrac ea (25). Levamisole inhibition and studies on suspensions of washed pl aque demonstrated that host-derived ALP contributed to >80% of the enz yme in GCF. We conclude that elevated 30-s GCF ALP levels measured usi ng the chemiluminescent assay reported, are detected before increase i n gingival indices and appear to be a better marker of gingival inflam mation than ALP concentrations. The Major source of ALP within GCF is host derived and in early inflammatory disease is likely to be polymop honuclear leukocyte origin.