Kinetics of Theta-Positive and Theta-Negative Lymphocytes in Thymus-Deprived and Normal Mice.

Abstract

Life spans and proliferative kinetics of theta-positive (.theta.+) and .theta.- cells were evaluated in normal, neonatally thymectomized (NeoTx) and sham-thymectomized (ShamTx) Balb/c mice. This was done by exposing cell suspensions, incubated with anti-.theta. antiserum + complement, to a dye exclusion test followed by fixation and autoradiography. Results from normal mice given [3H]thymidine injections 5 wk before being killed indicated that long-lived .theta.+ and .theta.- cells constituted about equal percentages of the respective populations in peripheral lymphoid tissues. Long-lived .theta.+ cells constituted a relatively high percentage of .theta.+ cells in the bone marrow, whereas a minority of the .theta.- lymphocytes were long-lived. Results from NeoTx and ShamTx mice, given intensive injections of [3H]thymidine, showed that the .theta.- cells of the mesenteric nodes were renewed at comparable rates in both groups of mice, whereas the .theta.+ cells were more rapidly renewed in NeoTx mice than in sham-operated littermates. In the bone marrow, the majority of .theta.- and .theta.+ cells were very rapidly renewed, indicating a production of these cells in the bone marrow of ShamTx mice and also in NeoTx mice, in which the number of bone-marrow .theta.+ cells was significantly higher than in ShamTx littermates.