PAS-C platelets contain less plasma protein, lower anti-A and anti-B titers, and decreased HLA antibody specificities compared to plasma platelets

BACKGROUND: Platelets (PLTs) collected and stored in PLT additive solution Intersol (PAS-C) are presumed to reduce recipient exposure to donor plasma components; however, the effects of PAS-C on PLT supernatant composition are poorly defined. Therefore, we compared the total protein concentration, isohemagglutinin titers, and HLA antibodies in supernatants of PAS-C PLTs to plasma PLTs. STUDY DESIGN AND METHODS: Apheresis PLTs from group O blood donors were collected into either 100% donor plasma (n = 50) or a mixture of 65% PAS-C/35% donor plasma (n = 50). Within 12 hours of collection, samples of the PLT supernatant were frozen and stored. PLT supernatants were assayed for total protein concentration and anti-A and anti-B titers and screened for HLA antibodies. Samples positive for HLA antibodies were further tested using single-antigen bead assays to determine antibody strength and specificity. RESULTS: Supernatants of PAS-C PLTs had significantly lower total protein concentration and anti-A and anti-B titers compared to plasma PLTs. There was no significant difference in the number of HLA antibody screen–positive PAS-C (3/50) compared to plasma PLT supernatants (2/50); however, the HLA antibody screen–positive supernatants of PAS-C PLTs had fewer HLA specificities (2) compared to those of the plasma PLTs (18). CONCLUSION: Decreased plasma proteins likely underlie lower rates of allergic and febrile, nonhemolytic transfusion reactions from the infusion of PAS-C PLTs. Decreased anti-A and anti-B titers may prevent hemolysis from minor ABO mismatch. Lower HLA antibody specificities may mitigate transfusion-related acute lung injury.