A blood processing system and method are disclosed that comprise a leukoreduction filter for removing leukocytes from red blood cells as the red blood cells pass through the filter; and a pump for pumping an additive solution through the leukoreduction filter to flush the leukoreduction filter of red blood cells that remain in the leukoreduction filter after filtration of the red blood cells. Additive solution is flowed through the leukoreduction filter at an initial flush rate to flush remaining red blood cells from the leukoreduction filter and the pump increases the flush rate of the additive solution during flushing of the leukoreduction filter.