To reconcile the role of Th cells in CLL proliferation and the CLL cell’s reliance on BCR signaling, we have outlined a mechanism by which Th cells amplify CLL BCR signaling by elevating CD45 activity through the CD45 natural ligand, galectin-1, and the sialoglycoprotein CD43.24 Here, PTPRC is linked to B-cell chronic lymphocytic leukemia.