Western blot analysis of sera for E-selectin. TNF-–stimulated HUVEC extracts (lane 1) and sera from the patient (lane 2) and from 2 normal donor controls (lanes 3 and 4) were transferred to nitrocellulose and immunoblotted with an anti–E-selectin antibody. A single molecular species was detected in the patient’s serum of approximately 100 to 110 kD, comparable in size with the form noted in control sera and appropriately smaller than the full-length species found in extracts from endothelial cells stimulated with TNF-.