Fewer SS RBCs adhered to laminin during HU treatment. (A) Blood samples from 7 healthy controls, 28 untreated (UT), and 34 HU-treated patients (HU). Horizontal lines represent medians. UT RBCs were more adherent than HU RBCs (2 dyn/cm², P = .007; Mann-Whitney test). Exposure to HU led to less dispersion of HU group values compared with the UT group (P < .001; Fisher exact test). (B) For the pre-post group, RBC adhesion was significantly lower after 6 months of HU (M6) than before (2 dyn/cm², n = 13; P = .013; Wilcoxon signed-rank test).