Effect of HU on E-selectin levels in lung and serum. (A) Measurements of soluble E-selectin in the serum of mice (SCA saline, n = 30, mean = 145 ± 45 ng/mL; SCA + HU, n = 35, mean = 98.5 ± 35.5 ng/mL). (B) Measurements of soluble E-selectin in the serum of humans (SCA/pre-HU, n = 92, mean = 77 ± 60; SCA/MTD, n = 57, mean = 31 ± 26; healthy controls, n = 18, mean = 22 ± 14) undergoing HU therapy. All groups significantly different (P < .001) from all other groups by 2-tailed t test (*compared with SCD mock; †compared with SCD + HU). (C-E) Representative sections of lung stained for E-selectin (purple) from SCA animals receiving saline (C), HU (D), or a negative control with no primary antibody (E). Magnification: left column, ×4; right column, ×10.