MATERIALS AND METHODS

Twenty-five volunteers from the Utah State Prison, in addition to the 45 subjects previously reported (1, 2), were used in these studies. All of the subjects were nor-mal healthy males, 20 to 50 years ofage, with normal leukocyte values. The subjects ate breakfast at 6: 00 am and the infusion of labeled blood was begun between 8: 00 and 10: 00 am

The methods for labeling blood in vitro, for the isolation of leukocytes from the blood samples, for the determination of leukocyte radioactivity, and for the calculation of the TBGP, CGP and T±have been described in previous publications (1, 2, 5). The GTR, defined as the number of granulocytes turned over through the blood each day per kilogram body weight, was calculated from the following equation (6): GTR= 24 X 0.693/Ti (hrs) X TBGP (no. cells X 107/kg). The DFP32 was purchased from the New England Nuclear Corp., Boston, Mass., as a dilute solution (1.0 mg per ml) in sterile, anhydrous propylene glycol. The con-centration of DFP was determined in our own laboratory by a modification of the method of Marsh and Neale (7). The specific activity of the material at the time it was used was 74 to 224/Ac per mg. Except when noted otherwise, DFP32 was added to the blood (400 to 500 ml) in the bag in a concentration of 0.3 1Ag per ml of whole blood.