Abstract:Lymphocyte circulation was studied in three hematologically normal humans and one patient with chronic lymphocytic leukemia, utilizing autologous blood lymphocytes which had been labeled with Na251CrO4. The final preparation consisted of at least 95% lymphocytes, and at least 95% of these cells were viable. During the first 30 minutes after infusion there was a rapid fall in blood activity which was associated with a rapid increase in splenic uptake in all four patients. Considerable radioactivity was noted over the liver throughout the study, but rapid changes similar to those occurring over the spleen were not noted during the initial 30 minutes after infusion. Little uptake was noted at any time over the bone marrow or lungs. After the first day there was a gradual fall in blood activity for approximately one week, and then the rate of decline was even less rapid. A somewhat similar disappearance curve was obtained for splenic activity. Uptake of label was comparatively greater over the liver after infusion of dead cells.