Rolling adhesion of L-selectin⁺ (300.19-L, top panel) and L-selectin⁻, but sLe^x+ (HL60, bottom panel) cells to TNF-α–stimulated HCMEC as a function of the duration of TNF-α incubation. At 1.07 dyne/cm², adhesion of 300.19-L increases at 4 to 5 hours of stimulation and remains elevated for at least 24 hours. Adhesion of HL60 increases at 3 to 4 hours of stimulation and returns to the control level within 18 hours. Mean values ±SEM, n = 2.