The present invention provides a humanized antibody or fragment thereof specific for the antigen CD45R0, wherein said antibody or fragment thereof comprises a humanized heavy chain variable domain comprising a CDR1 region of SEQ ID NO:1, a CDR2 region of SEQ ID NO:2, and a CDR3 region of SEQ ID NO:3, and a humanized light chain variable domain comprising a CDR1 region of SEQ ID NO:4, a CDR2 region of SEQ ID NO:5, and a CDR3 region of SEQ ID NO:6. It is also provided the use of the present antibody or fragment thereof for enrichment or depletion of CD45R0-expressing cells from a sample comprising CD45R0-expressing cells.