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Transient populations of terminal transferase positive (TdT+) cells in juvenile rats and mice
Insights
Transient populations of terminal deoxynucleotidyl transferase-positive (TdT+) cells are found in young rodents. These cells, sensitive to dexamethasone, differ in origin and location, with only bone marrow and thymus TdT+ cells persisting into adulthood.
Area of Science:
- Immunology
- Developmental Biology
- Cell Biology
Background:
- Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase expressed in immature lymphocytes.
- TdT expression is a marker for specific cell populations during development.
- Understanding TdT+ cell distribution provides insights into immune system maturation.
Purpose of the Study:
- To characterize transient populations of TdT+ cells in young rodents.
- To determine the origin and fate of TdT+ cells in peripheral tissues.
- To investigate the sensitivity of these transient TdT+ cells to dexamethasone.
Main Methods:
- Flow cytometry and immunofluorescence to detect TdT expression.
- Analysis of TdT+ cell populations in peripheral blood, lung, liver, spleen, bone marrow, and thymus of rats and mice.
- Studies in nu/nu mice to assess thymic dependency.
- Treatment with dexamethasone to evaluate cell sensitivity.
Main Results:
- Transient TdT+ cell populations were identified in peripheral blood, lung, liver, and spleen of rats and mice from birth to 7 weeks.
- Peripheral blood TdT+ cells appear post-thymic, absent in nu/nu mice.
- Lung, liver, and spleen TdT+ cells appear prethymic.
- All transient TdT+ cell populations were sensitive to dexamethasone.
- Only TdT+ cells in bone marrow and thymus persist into adult life.
Conclusions:
- Rodent immune systems exhibit transient, developmentally regulated TdT+ cell populations in various tissues.
- These transient TdT+ cells have distinct origins (prethymic and post-thymic) and are sensitive to glucocorticoids.
- Bone marrow and thymus are the primary long-term reservoirs for TdT+ cells, highlighting their crucial role in lymphocyte development.
Abstract:
Transient populations of TdT+ cells are present in peripheral blood, lung, liver, and spleen of rats and mice between birth and 7 wk of age. TdT+ blood cells appear to be post-thymic cells, as evidenced by their absence from nu/nu mice and their pattern of TdT fluorescence. TdT+ cells in lung, liver, and spleen appear to be prethymic cells. All transient populations of TdT+ cells are sensitive to dexamethasone. Only TdT+ cells in bone marrow and thymus persist into adult life.