Before revision:  The theory allows us to calculate an effective order parameter, temperature, external field, and heat capacity from T cell fluorescence data without fitting.
After revision:  Making this statement quantitative requires the appropriate mapping between the biochemical parameters and the Ising parameters. Here we derive this mapping rigorously and uniquely for a broad class of stochastic birth-death models with feedback, and show that the expected static and dynamic critical exponents emerge. The generality of the mapping allows us to calculate an effective order parameter, temperature, external field, and heat capacity from T cell fluorescence data without fitting.