T-cell Receptor Diversity During Acute Thymic Atrophy and Resumption

The human body hosts an immense pool of T-cells, and each is capable of responding to a specific antigen. The thymus provides a constant supply of new cells to the peripheral blood. While most circulating T-cells are unique in their antigen specificity, some divide to create clones of identical cells. The thymus experiences acute atrophy during physiological duress, for example during infection, starvation, or psychological distress. Atrophy is accompanied by a dramatic decrease in T-cell export, from which the thymus typically recovers after removal of the stressor. We present an ODE model quantifying the effect of this atrophy and subsequent recovery on the size of the peripheral T-cell pool, which is able to distinguish between clones of different sizes. We find that the time scales of T-cell eradication during thymic collapse and regeneration after recovery are proportional to the disparity in homeostatic cellular proliferation and death rates.