Increased adherence of blood PMNs to untreated and TNF-treated cultured endothelium in sickle cell crisis. Summary of results comparing the adherence of PMNs from 18 control subjects and 18 sickle cell patients in crisis to (A) untreated and (B) TNF-treated endothelium and of PMNs from 25 control subjects and 25 patients out of crisis to (C) untreated and (D) TNF-treated endothelium. Each line represents an experiment in which PMNs from 1 patient and 1 control subject were incubated with endothelial monolayers prepared from the same umbilical cord vein. Half of the monolayers had been pretreated with 10 U/mL TNF for 4 hours. ⁵¹Cr-labeled PMNs (2 × 10⁵/100 μL) suspended in DMEM with 10% autologous serum were added to confluent monolayers in 96-well microtiter plates. After coculture for 1 hour at 37°C, the nonadherent PMNs were removed by washing, the monolayer was lysed by 0.1 N NaOH, and the radioactivity associated with adherent PMNs was counted. The results, which are the mean value of quadruplicate measurements, are expressed as the percentage of adherent PMNs in relation to the total number of PMNs added to the monolayers. Overall, the PMNs from patients in crisis were more adherent than control PMNs to untreated endothelial monolayers (P < .001) and to TNF-treated monolayers (P = .002).