CD44 blockade reduces homing of murine and human leukemic cells. (A) Scheme of short-term adoptive transfer approach. CTV-stained splenocytes of Tcl1-tg mice with anti-CD44 antibody (clone KM201) treatment or untreated controls (UTC) were injected into the tail veins of C57BL/6J recipients. Alternatively, human PBMCs from CLL patients with or without anti-CD44 antibody (clone 515) treatment were injected into nonobese diabetic/severe combined immunodeficiency (NOD/SCID) recipients. After 3 hours, the number of CD5⁺/CD19⁺ cells that had homed to SPL and BM of the recipients was determined by flow cytometry using human-specific anti-CD45, anti-CD5, and anti-CD19 antibodies. (B) The rate of CD5⁺/CD19⁺ cells from Tcl1-tg mice that had homed to SPL and BM of the recipients was determined in 4 independent experiments. In each experiment, technical duplicates were performed. (C) The rate of CD5⁺/CD19⁺ cells from CLL patients that had homed to SPL and BM of the recipients was determined in 7 independent experiments using samples from 7 different CLL patients (all CD49d⁺, 4 MCLL, 3 UMCLL). In each experiment, technical duplicates were performed, and they were averaged for the analysis.