Subpopulations within “short-lived” and “long-lived/rd lymphocytes resolved by isopycnic sedimentation in Ficoll solutions coupled with a double radioisotopic labeling technique

Abstract

The distribution of “short-” and “long-lived” cells among the subpopulations of the cells in lymphoid tissues of the rat has been examined by means of isopycnic density gradient centrifugation in solutions of Ficoll. Employing a double isotope counting technique, the “long-lived” cells were labeled by their ińcorporation of multiple doses of tritiated thymidine over a 14 day period while the “short-lived” cells in the same animals were similarly labeled by the incorporation of 14C-labeled thymidine over a 40 h period. The reported tissue distribution of short-lived and long-lived lymphocytes was confirmed. In addition, the existence of discrete subpopulations of cells having varying apparent half lives in some of the tissues was demonstrated.