“…For example, the endothelial cell stimulant DDAVP (desmopressin) induces raised levels of von Willebrand factor but not soluble P-selectin in vivo (Jilma et al, 1996). Furthermore, we have been unable to detect P-selectin, but plentiful von Willebrand factor, by enzyme-linked immunosorbent assay (ELISA), in human umbilical vein endothelial cell lysates or tissue culture supernatants (data not shown), whereas P-selectin is easily detected in platelet lysates and from the 'supernatants' of aged endothelialcell-free platelet concentrates designed for transfusion (Kostelijk et al, 1996). However, more pertinent data arise from the measurement of soluble P-selectin in paired serum and plasma.…”