T cell fate has many extrinsic, intrinsic, and stochastic influences, that can act over widely different time scales and can be subtle or strongly deterministic. Many of these influences have been characterised, but parsing how these influences are assimilated into reliable control of T cell differentiation during development or activation is a major challenge, and not achievable with traditional methods of population-based experimental intervention and analysis. However, observing single cells over time offers new possibilities for determining the extent to which individual molecular events and their functional interactions impact upon cell fate.
Asymmetric cell division (ACD) has been identified during both T cell activation and T cell development. However, the extent to which ACD influences T cell fate is not yet clear. To determine how ACD influences fate we developed an approach based on time lapse imaging to monitor, at the single cell level, both molecular events at division and subsequent fate events. This enables us to assess statistical correlations between temporally distinct events (days apart) in the same cell. Here, we apply this approach to the beta-selection stage of T cell development. These analyses demonstrate a role for ACD in subsequent cell fate events and provide proof-of-principle for a general approach to parse the role of molecular events in regulating subsequent fate determination.