On the role of the pre T cell receptor in αβ versus γδ T lineage commitment

The role of the pre-T cell receptor (TCR) in lineage commitment to the gamma delta versus cup lineage of T cells was addressed by analyzing TCR beta chain rearrangements in gamma delta T cells from wild-type and pre-TCR-deficient mice by single cell polymerase chain reaction. Results show that the pre-TCR selects against gamma delta T cells containing rearranged V beta genes and that gamma delta T cell precursors but not gamma delta T cells express the pre-TCR alpha protein. Furthermore, pre-TCR-induced proliferation could not be detected in gamma delta T cells. We propose that the pre-TCR commits developing T cells to the cup lineage by an instructive mechanism that has largely replaced an evolutionary more ancient stochastic mechanism of lineage commitment.