Disclosed is an isolated antibody that binds specifically to human P-Selectin Glycoprotein Ligand I without interfering with binding between P-Selectin Glycoprotein Ligand I and P- Selectin, wherein the antibody, upon binding to P-Selectin Glycoprotein Ligand I on an activated T-cell, induces the death of the activated T-cell, wherein the antibody is an antibody selected from the group consisting of: (a) an antibody comprising a light chain comprising SEQ ID NO: 25; and (b) an antibody comprising a heavy chain comprising SEQ ID NO: 26.