Note
We report here a method by which functional human PBL may be recovered from a blood product preparation unit (Leukotrap) which is normally employed by blood banks to prepare a leukocyte-poor blood product and which is commonly discarded after use. Blood filters which were back-flushed with cold, phosphate-buffered saline (PBS) and the resulting buffy coats collected and separated on Histopaque gradients yielded an average of 2.7 × 108 (±1.17 × 108) cells per filter processed (n = 38), with viability greater than 95%.