Abstract: There is proposed an apparatus for isolating and recovering an objective cell, which comprises, a filtering device having a filtering member which is capable of setting a porosity thereof to two or more different porosity, a first line for feeding a priming liquid to the filtering device, a second line for feeding a liquid to be treated containing the cell aimed to isolate to the filtering device, and a third line provided with a storage container for storing the priming liquid that has been passed through the filtering device, wherein the priming liquid stored in the storage container is employed for washing the filtering device. There is also proposed a method for isolating and recovering an objective cell using the aforementioned apparatus.

Abstract: A method of separating cells from blood by using a filter apparatus having first and second ports and a filter member therebetween having a changeable porosity. The filter member includes a stack of porous polymer sheets that preferably has a gradient of a physical or chemical characteristic in the direction of stacking. This can include a gradient in porosity, hydrophilicity or zeta potential. In a first step, blood is filtered through the apparatus when the filter member is set to a compressive state having a first porosity capable of capturing the objective cells. In a later step, the filter member is then set to a non-compressive state having a second porosity, higher than the first, for recovering the objective cells. The change in porosity results from the enlargement or reduction of the diameter of the pores of the filter member. The method can also include washing the filter member when the member is set to a porosity that is higher than the first porosity but lower than the second porosity.

Abstract: A material wherein a polyamine compound is immobilized on its base surface and a blood filter using this material. The material is provided in the form of a porous membrane having the maximum pore diameter of 0.1-50 .mu.m. The polyamine compound is at least one compound selected from the group consisting of (a) a polyamine compound which has primary and secondary amines in its molecule and a hydrophobic part between these amines, (b) a polyamine compound represented by the following formula (I); ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 represent hydrogen, aliphatic and aromatic hydrocarbons, and halogen, and n is 5 or more, and (c) a polyamine compound represented by the following formula (II); ##STR2## wherein R represents NH.sub.2 or aminoalkyl radical having 1 to 4 carbon atoms and n is 5 or more. The blood filter comprises a housing which has an inlet and outlet, and the material arranged inside the housing.