HU-exposed SS RBC adhesion to laminin decreased, whereas Lu/BCAM erythroid expression increased. Lu/BCAM expression was measured by flow cytometry using anti-Lu monoclonal antibody F241. (A-B) SS RBC adhesion as a function of the percentage of RBCs from 12 untreated (UT) and 14 HU-treated patients expressing Lu/BCAM (Lu/BCAM⁺; A) or of Lu/BCAM MFI (B). (C-D) Lu/BCAM expression level on the surface of RBCs from 19 UT and 19 HU-treated patients represented as the percentage of circulating RBCs expressing Lu/BCAM (C) and the latter's MFI (D). HU increased the percentage of Lu/BCAM-positive RBCs (P < .001) and Lu/BCAM MFI (P < .001; Mann-Whitney test). Horizontal lines represent medians. (E-F) Same as panels C and D for the 5 pre-post group patients before (D0) and during HU treatment (D15, M2, M4, and > M6).