Figure 1a. An equation to describe how individual B cells contribute to total IgG production within a population.

IgG is the total IgG secreted, PB_live is the number of live B cell blasts, φ_ASC is the fraction of live cells that are secreting IgG, σ_IgG is the rate of IgG secretion per cell, t is time and t_inc is the incubation time of the assay. 1b. Hypotheses for the relationship between cell division and IgG secretion range of B cell populations. The secretion rate maturation hypothesis posits that memory B cells stimulated to differentiate into B cell blasts increase their σ_IgG with each subsequent mitosis such that cells that have divided more times secrete IgG at a higher σ_IgG. An alternative possibility is that σ_IgG are independent of division class, behaving more like a binary “On/Off” switch. In this model, dividing cells secrete IgG in the same range, irregardless of division number and control of population IgG secretion is asserted through control of φ_ASC. In the third “mixture” hypothesis, several subpopulations of memory B cell blasts produce different σ_IgG distributions.