Signals involved in gamma/delta T cell versus alpha/beta T cell lineage commitment

In seeking an explanation for the complexity of tissue development, biologi sts are obliged to explain lineage commitment, the events that dictate whet her or not a progenitor . cell will differentiate into one cell type or ano ther. Such explanations have been sought across a broad spectrum of biologi cal systems, although in no case has a full understanding been developed. F or immunologists, attention has been focused on the lineage commitment of a T cell progenitor to becoming either a gamma delta T cell or an ap T cell. In this review, we compare the signals that thymocytes may receive from om the pre T cell receptor (preTCR) with signalling from TCR gamma delta. The se signals may determine, co-determine, facilitate, or cement the alpha bet a/gamma delta lineage decision, in, concert with signals from additional mo lecules, such as Notch and cytokine receptors. Elucidating the pleiotropic signalling eve nts, particularly those elicited by the preTCR, may in the n ear future contribute to a molecular ddefinition of lineage commitment.