Leukocyte Labeling With 51 Chromium . III .

The kinetics of radiochromate-labeled was found to be about twice the size autologous blood lymphocytes were of the blood lymphocyte pool constudied in normal subjects. The labeled tamed within it and turned over cells equilibrated within hours with a through the blood about 12 times daily. recirculating lymphocyte pool (ALP) The labeled cells had an average half distributed between the blood, the life in the RLP of 18 days. spleen, and the bone marrow. The RLP R ADIOCHROMATE (51Cr) is a particularly useful blood cell label because it allows assessment of in vivo cell distribution. Studies of lymphocyte kinetics with 51Cr show a complex pattern. There is an initial rapid exponential clearance of the cells from the blood and a coincident rise in body surface counting rates over the spleen and the sacral marrow. There follows a gradual decline in the levels of blood and organ radioactivity.’3 This pattern is cornpatible with the recirculation of the lymphocytes between the blood and tissues4 and their subsequent loss from the recirculating lymphocyte pool (RLP) by death or redistribution. In the present investigation, the size, distribution, and intravascular turnover rate of the RLP and the life span of cells in the pool have been studied in normal human volunteers.