The Evolutionary Conservation of Two Classes of T Lymphocytes, Those $\alpha$

question 18

Essay

The evolutionary conservation of two classes of T lymphocytes, those expressing $\alpha$ : $\beta$ T-cell receptors and those expressing $\gamma$ : $\delta$ T-cell receptors, argues for important but separate functions of these two classes of T cells. Evolution has also conserved the process of somatic recombination of gene segments that is able to generate an enormous diversity of $\alpha$ : $\beta$ and $\gamma$ : $\delta$ T-cell receptor sequences. Do these observations indicate that both classes of T cells are components of the adaptive immune system? Why or why not?

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