The neutrophil-priming cytokine sCD40L accumulates in stored apheresis platelet (left panel) and red-cell (right panel) components. Filters used to remove leukocytes from red cell components also remove platelets and retard the accumulation of sCD40L in leukocyte-reduced red cell components (LR). At the end of the 42-day storage period the levels of sCD40L in red cells that have not been leukocyte reduced (NLR) are similar to the levels in apheresis platelets after 5 days of storage. See the complete figure in the article beginning on page 2455.