Lu/BCAM phosphorylation (P), RBC adhesion, and evolution of 3 blood parameters during HU treatment. (A) Typical results (1 of 5 experiments) obtained with pre-post group patient's SS RBCs showing the phosphorylation of the Lu-gp long isoform after RBC radiophospholabeling and immunoprecipitation of Lu/BCAM. The percentage of reticulocytes was determined by flow cytometry of each sample. Total immunoprecipitated Lu/BCAM proteins were quantified by WB. The P/WB ratio estimates the proportion of phosphorylated proteins. (B) Box and whiskers represent Lu/BCAM phosphorylation in 5 patients before (D0) and during HU treatment (D15, M2, and > M6); internal horizontal line, median; lower and upper box limits, 25th and 75th percentiles; and T-bars, range. HU significantly decreased Lu/BCAM phosphorylation (P = .005; Friedman test, AU indicates arbitrary units). (C) Lu/BCAM-phosphorylation change after 6 months of HU treatment for each of the 5 patients. (D) Evolution of RBC adhesion under treatment for the 5 HU-treated patients. (E) A linear-regression analysis between RBC adhesion and Lu/BCAM phosphorylation (P < .001, r² = 0.496). (F-H) Box and whiskers represent the evolution of reticulocyte percentages, Hb concentrations and HbF percentages, respectively.