Blood filter for leukocytes

In a white cell filter for blood a housing defining a blood inlet and an outlet at respective ends thereof, said housing enclosing and carrying a tubular, non-woven fiber filter element with one of said inlet and outlet communicating with the interior of said tubular filter element and the other of said inlet and outlet communicating with the exterior thereof, said filter element defining fiber diameters adapted to adsorb and temporarily hold white cells from blood passing therethrough, the improvement comprising, in combination:

• said fiber filter element having a thickness of 0.2 to 0.6 inch, said fibers being bonded together to define a generally fixed average interstitial spacing which is gradated in size to be less at the inner surface of said tubular filter element than at the outer surface thereof, and in which said filter element is retained in said housing at both ends by first and second blood-compatible, elastomeric retention members, the ends of said filter element being integrally attached to and commingled with said retention members, said first retention member also defining a housing end seal and further defining an aperture for one of said inlet and outlet, said second retention member defining a seal of a bore of said tubular filter element and defining about its periphery a plurality of spaced, peripheral ribs engaging the inner wall of said housing and defining flow channels between said ribs, said ribs being compressed by said inner wall to insure the seal between the seal of said filter element and the second retention member.