Antibodies against CD41 (clone MWReg30) impair LT repopulation of WT HSCs. (A) Representative FACS plots showing the staining pattern of the MWReg30-PE (anti-CD41) antibody used for blocking experiments in panels B and C, on WT (top right) or CD41-KO (bottom right) LSKCD150+ LT-HSCs. IgG1, κ isotype control staining shown in left column. Note the absence of MWReg30 staining on CD41-KO HSCs confirming its specificity for HSC-bound CD41 antigen. (B) Blocking antibody competitive transplantation setup: WT cells were incubated with isotype or MWReg30 antibodies and injected into recipients mixed at equal ratios (1:1; 200 000 + 200 000) with congenic WT BM competitor cells. (C) Bar diagrams showing donor chimerism level in peripheral blood of recipient mice at 1, 2, and 4 months after transplantation (n = 10-11). Error bars, SEM, **P < .01, ***P < .001 by Student t test.