Residual MC are associated with a storage-induced reduction in platelet immunity. A total of 10⁸ platelets from (A) BALB/c mice or (B) anti-AsGm1–treated SCID mice were either transfused fresh (within 4 hours of collection, ○) of after 18 hours of storage (□) into CBA recipients (n = 10). Data is expressed as the percentage of mice which become IgG antidonor antibody positive during the weekly transfusion protocol.