Comparative morphology of granulocytes collected by three methods of leukapheresis. A light microscopy and transmission electron microscopy study.

The morphology of granulocytes collected by continuous-flow centrifugation (CFC), discontinuous-flow centrifugation (DFC), and continuous-flow filtration (CFF) was investigated in 18 healthy donors by means of light microscopy and transmission electron microscopy. Light microscopy study of semithin sections of granulocytes collected by CFC and DFC showed minimal morphologic abnormalities, compared to granulocytes procured by CFF. Ultrastructural study of granulocytes procured by CFF showed more conspicuous qualitative and quantitative abnormalities (the most prominent being "microvilli," degranulation, and bazarre chromatin) than in granulocytes obtained by the other two methods. Controls showed that the bulk of CFF-cell abnormalities was due to the "tapping" of the filters. Factors such as the mechanical compression (plasma extractor) used in DFC method, donor pretreatment with anticoagulants and steroids, hydroxyethyl starch, and duration of leukapheresis scarcely influenced granulocyte morphology.