The Purification of Red Cells for Transfusion by Freeze‐Preservation and Washing. IV. The Use of Micropore Filtration To Reduce the Residual HL‐A Antigenicity of Previously Frozen, Washed Red Cells

Using a semi‐quantitative HL‐A antibody adsorption assay, a reduction in HL‐A antigenicity was observed in 15 of 22 units of previously frozen and washed red blood cells after passage through a micropore transfusion filter. Red blood cell viability was unaffected by this procedure. Micropore filtration was a simple adjunct to the freezing and washing of red blood cells that may further reduce histocompatibility antigen exposure in transfused recipients.