Universality of biochemical feedback and its application to immune cells
We make rigorous the notion of universality in well-mixed stochastic models of biochemical feedback, namely that they scale near their bifurcation point according to the exponents of the mean-field Ising universality class. In doing so, we derive a mapping of the biochemical parameters to an effective temperature, magnetic field, order parameter, and heat capacity. These effective thermodynamic quantities can be extracted from biological data without fitting or knowledge of the underlying molecular details. We demonstrate this procedure on fluorescence data from mouse T cells and interpret the findings. In the process, we discover an unanticipated result: the heat capacity allows inference of absolute molecule number from fluorescence intensity. We explain this result in terms of the underlying fluctuations and demonstrate the generality of our work.
PDF Abstract