Tissue plasminogen activator and placental plasminogen activator inhibitor in human gingival fluid

Abstract

Gingival crevicular fluid (GCF) is an extracellular exudate protecting periodontal tissue. Pathological changes in the periodontium are reflected in the composition of GCF. Crevicular fluid was collected from healthy volunteers on Millipore ® filter disks, and eluted at 100-fold dilution. The samples were tested for fibrinolytic activity and the presence of the plasminogen activators, t-PA and u-PA, and the specific plasminogen activator inhibitors, PAI-1 and PAI-2. In the diluted samples, t-PA was found at concentrations of 4–33 gmg/l, and PAI-2 at concentrations of 19–84 μg/l, whereas u-PA and PAI-1 were hardly detectable. Analyses of parotid and whole saliva yielded no evidence of gingival fluid contamination from these sources. The fibrinolytic activity of gingival fluid was completely quenched both by antibodies against t-PA and by PAI-2, indicating the presence of t-PA in its two chain form which is more susceptible to inhibition. This inhibition by PAI-2 may serve a regulatory purpose and prevent excessive proteolysis and tissue destruction.