The unit has an outer casing comprising inlet orifice (2) and an outlet orifice (3), where the outer casing encloses a porous element arranged between the inlet orifice and the outlet orifice. The porous element comprises a leukocyte-removal medium comprising a coating that includes a polymer having a main hydrophobic chain and a hydrophilic poly(ethylene oxide) side chain. A mass percentage of hydrophilic poly(ethylene oxide) side chain is less than about 50% of mass average molar mass of the polymer. An independent claim is also included for a system for removing leukocytes from a fluid containing blood platelets.
