Efficiency of leukocyte removal by filters made of superfine glass fiber membranes

Background and Objectives: To demonstrate the application of leukocyte remo val filters made of a new type of filter material - superfine glass fiber - for depleting leukocytes in SAGM red cell suspensions and preventing nonhe molytic transfusion reactions. Materials and Methods: The extent of leukocy te depletion and red cell recovery was based on cell counts. Trace leukocyt es were counted in a 50-mu l Nageotte counting chamber or by using a Row cy tometer. The chemical stability of the glass fiber membranes was studied by plasma emission spectrometer and by measuring the ion content and weighing nonvolatile matter in water extract. The structural stability of the glass fiber membranes was studied by a micropore-filter membrane method. Results : Leukocyte removal filters made of superfine glass fiber membranes removed more than 99.0% of leukocytes in SAGM red cell suspensions prepared from 4 00 ml whole blood. Red cell recovery exceeded 90%, and the total number of residual leukocytes was less than 5x10(6), A water extract of the glass fib er membranes contained only traces of Si4+ and Ca2+ and less than 2 mg/100 ml of nonvolatile matter. No broken or loose fibers were found in the filte rs. Scanning electron microscopy showed that the web structure of the glass fiber membranes was instrumental in trapping and holding leukocytes. Concl usion: A filter made of glass fiber membranes is effective in leukocyte dep letion.