Filter device

A biological fluid processing device comprising:

• (a) a housing comprising an inlet portion including an inlet portion inlet port, and a separate inlet portion elution fluid outlet port, an outlet portion including an outlet portion outlet port and an outlet portion elution fluid inlet port, and defining a first fluid flow path between the inlet portion inlet port and the outlet portion outlet port and a second fluid flow path between the outlet portion elution fluid inlet port and the inlet portion elution fluid outlet port;
• (b) a porous fibrous leukocyte depletion filter having a first surface and a second surface, disposed in the housing across the first fluid flow path and across the second fluid path;
• and
• (c) a first perforated diffusing plate having a first surface and a second surface and asymmetrically shaped perforations through the first perforated diffusing plate, the asymmetrically shaped perforations having larger internal diameters at the second surface of the first perforated diffusing plate than at the first surface of the first perforated diffusing plate, the first perforated diffusing plate being disposed in the housing across the first fluid flow path and across the second fluid path, wherein the first perforated diffusing plate is disposed in the housing between the second surface of the porous fibrous leukocyte depletion filter and the outlet portion outlet port and the outlet portion elution fluid inlet port, the first surface of the first diffusing plate facing the second surface of the porous fibrous leukocyte filter.