Granulocyte transfusion is effective for treating some intractable infections. We have recently developed a simple bag method for collecting granulocytes without using apheresis. A recombinant human granulocyte colony-stimulating factor (G-CSF) (50, 100, 200, and 400 microg nartograstim) was administered to 5 healthy male adult volunteers. The quantity and quality of the collected granulocytes were evaluated. The G-CSF dose proportionally increased the collected neutrophil count. The count of collected neutrophils correlated strongly with the count before collection (r2 = 0.684; P < .001). The neutrophil counts collected from 200 mL whole blood were 0.90 x 10(9), 1.68 x 10(9), 2.40 x 10(9), and 2.99 x 10(9) at 50, 100, 200, and 400 microg G-CSF, respectively. There was no significant difference in neutrophil counts between the 200-microg and 400-microg doses. doses. Concerning granulocyte functions, active oxygen production and phagocytic capacity were not affected by irradiation with 15 Gy. Transient arthralgia occurred in 2 subjects. A single administration of 200 microg G-CSF enabled the collection of large quantities of granulocytes by the bag method. We consider that the collection of granulocytes by the bag method from 400 mL of whole blood drawn twice can theoretically provide 3 x 10(8)/kg of granulocytes for treating children weighing less than 30 kg.