The response of human sulcular leucocytes to a chemotactic challenge: A new in vivo assay

We monitored the in vivo response of human and rat crevicular leucocytes (CL) and fluid (CF) to a chemical challenge in an attempt to develop an in vivo chemotaxis assay. The mesial crevices of #21 and #22 of male dental students (mean GI = 0; crevice depth = 2.3 mm) were washed and air dried. The baseline values for CL (#num;21) and CF (#22) were recorded. CL were collected in 10 μI washes of the crevice and an aliquot immediately counted in a hemacytometer. CF was collected on filter paper strips and measured with a fluid meter. Casein, a nutrient and a standard in vitro chemo‐attractant was applied with a calibrated wire loop into each crevice. CL and CF were monitored 15 min later and at 5 min intervals up to 45 min. CL and CF peaked approximately 30 min after the casein challenge; both parameters returned to baseline rapidly thereafter. In rats, a dose‐response was obtained when concentrations of 0.01–4.0 mg casein/ml were applied to the gingival crevice. The maximum response of CL and CF occurred at 2.0 mg/ml. The application of buffer alone or Fab protein, which lacks chemotactic activity, produced no rise in CL and CF. We suggest that this crevicular technique can be used to monitor the in vivo response of subjects with defects in leucocyte chemotaxis.