A fit of CD4 T cell immune response to an infection by lymphocytic choriomeningitis virus.

We fit an immune response model to data reporting the CD4 T cell numbers from the 28 days following the infection of mice with LCMV. We used an ODE model that was previously used to describe qualitatively the behaviour of CD4 T cells, regulatory T cells (Tregs) and interleukine-2 (IL-2) density. The model considered two clonotypes of T cells in order to fit simultaneously the two time series for the gp61 and NP309 epitopes. We observed the proliferation of T cells and, to a lower extent, Tregs during the immune activation phase following infection and subsequently, during the contraction phase, a smooth transition from faster to slower death rates. The six parameters that were optimized were: the beginning and ending times of the immune response, the growth rate of T cells, their capacity, and the two related with the homeostatic numbers of T cells that respond to each epitope. We showed that the ODE model was able to be calibrated thus providing a quantitative description of the data.