Experimental Hematology Department, Armed Forces Radiobiology Research Institute, Bethesda, Maryland

Granulocytes from dogs obtained by continuous-flow centrifugation leukapheresis were purified by counterflow centrifugation-elutriation using a modified rotor and enlarged separation chamber. The separation chamber has a threefold increase in volume capacity, as compared to the commercial Beckman Instruments' separation chamber, and the quantity and purity of the granulocytes recovered are suitable for purified granulocyte transfusion studies in a 10-kg canine animal model. Transfusion of these cells into cyclophosphamide-induced neutropenic animals permits an analysis of granulocyte chemotactic ability in terms of migration into skin chambers filled with endotoxin-activated serum. The purified granulocyte function in vivo was compared to the activity of granulocytes present in leukapheresis concentrates. The data show that transfused granulocytes isolated by counterflow centrifugation-elutriation from leukapheresis concentrates retain identical in vivo chemotactic activity, as compared to granulocytes present in transfused leukapheresis concentrates.