Relative NF-kB activation in HUVEC in response to interaction of RBC. HUVEC were incubated with either AA RBC (n = 3; two different donors ) for 1 hour and 4 hours or with SS RBC (n = 4; three different donors and one replicate) for 1 hour in the absence and presence of E-CM. Nuclear extracts were probed for NF-kB activity. The NF-kB activity in the gel (not shown) was quantified by densitometric scan of the autoradiograph by Alpha Image 2000 Documentation and Analysis system. The data shown is relative change in NF-kB activity compared to untreated HUVEC. NF-kB activity increased to 365% ± 34% (range, 320% to 425%) on incubation of HUVEC with SS RBC and E-CM. Replicate of the same donor sample showed less than 10% variation.