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T-cell and natural killer cell development in thymectomized Xenopus
J D Horton1, T L Horton, R Dzialo
1Department of Biological Sciences, University of Durham, UK. j.d.horton@durham.ac.uk
Immunological Reviews
|January 23, 1999
Summary
Early thymectomy in Xenopus frogs severely impairs T-cell development, suggesting T cells are thymus-dependent in this amphibian. This model aids in studying natural killer (NK) cell evolution.
Area of Science:
- Immunology
- Developmental Biology
- Evolutionary Biology
Background:
- The thymus is crucial for T-cell development in vertebrates.
- The existence and extent of extrathymic T-cell development pathways in early vertebrates remain debated.
- Natural killer (NK) cells are key components of the innate immune system, but their evolutionary origins are not fully understood.
Purpose of the Study:
- To investigate the role of the thymus in T-cell development using the Xenopus early-thymectomy model.
- To explore the evolution of natural killer (NK) cells.
Main Methods:
- Early thymectomy was performed on Xenopus larvae.
- T-cell function, surface marker expression, and T-cell receptor beta transcript levels were assessed in thymectomized and control frogs.
- In vitro studies examined the cytotoxic activity of splenocytes from thymectomized and control Xenopus.
Main Results:
- Thymectomy led to a significant loss of T-cell function and reduced T-cell surface marker expression.
- T-cell receptor beta transcript levels were greatly diminished in spleen, liver, and intestine of thymectomized individuals.
- Splenocytes from thymectomized Xenopus exhibited natural cytotoxicity against target tumor cells.
Conclusions:
- T-cell development in Xenopus is predominantly thymus-dependent, challenging the notion of substantial extrathymic T-cell development in early vertebrate evolution.
- The Xenopus thymectomy model, which results in a permanent T-cell deficiency, offers a valuable phylogenetic model for studying NK cell development and function.