Production of HLA class I eluted platelets on a clinical scale using a u-shaped hollow fiber filtration device and citric acid elution

HLA‐Alloimmunization remains a significant problem in platelet transfusion therapy. HLA‐eluted platelet products could aid in the supportive therapy of these patients, because they are readily available in contrast to HLA‐matched platelets. Until now the major drawback of these products were the cumbersome preparation and standardization of such products. Hollow fiber separation systems could be an alternative preparation method because they are based on gravity separation which means there are no centrifugation steps involved. This ensures a very gentle treatment of the platelets with no activation. Single donor platelets were eluted with citric acid and washed three times using a U‐shaped hollow fiber filter device. Products were evaluated for their antigen expression using directly labeled specific monoclonal antibodies for HLA class I (w6/32, FITC labeled) and platelet glycoproteins specific monoclonal antibodies (CD41a PE labeled, CD42 PE labeled) using flow cytometry. Using ten apheresis platelet products and a citric acid elution technique for HLA class I antigen elution we were able to prepare HLA‐eluted platelet products which expressed less then 20% of their initial amount of HLA class I on their surface. The whole procedure took less than three hours. The surface density of platelet specific glycoprotein complexes was unaffected by the procedure. Production of HLA‐eluted platelet products on a clinical scale in a closed system is feasible and can be a good option for the platelet support of HLA class I immunized patients.