Results were obtained from 6 patients in crisis and 6 healthy controls. The table shows the distribution of CD64⁺ cells in PMN preparations before addition to endothelial monolayers and also in PMNs bound to the monolayers. The percentage of PMNs expressing CD64 before and after coculture with endothelium was determined by flow cytometry and immunochemistry, respectively. For the latter technique, PMNs were incubated with endothelial cells grown in 16-well chamber slides. After incubation for 1 hour at 37°C followed by washing, the monolayers were fixed with formaldehyde, stained with anti-CD64 antibody, and then developed by avidin-peroxidase. The number of CD64⁺ cells in the wells was calculated by counting 100 adherent PMNs under light microscopy. Each reading is the mean value obtained from triplicate wells. Endothelial-bound PMNs from both patients in crisis and normal subjects were found to be predominantly CD64⁺ cells.

P < .02 by the unpaired Student's t-test.

P < .001 by the unpaired Student's t-test.