A theory of coalescence of signaling receptor clusters in immune cells

A theory of coalescence of signal receptor clusters in mast cells is developed in close connection with experiments. It is based on general considerations involving a feedback procedure and a time-dependent capture as part of a reaction-diffusion process. Characteristic features of observations that need to be explained are indicated and it is shown why calculations available in the literature are not satisfactory. While the latter involves static centers at which the reaction part of the phenomenon occurs, by its very nature, coalescence involves dynamically evolving centers. This is so because the process continuously modifies the size of the cluster aggregate which then proceeds to capture more material. We develop a procedure that consists of first solving a static reaction- diffusion problem and then imbuing the center with changing size. The consequence is a dependence of the size of the signal receptor cluster aggregate on time. A preliminary comparison with experiment is shown to reveal a sharp difference between theory and data. The observation indicates that the reaction occurs slowly at first and then picks up rapidly as time proceeds. Parameter modification to fit the observations cannot solve the problem. We use this observation to build into the theory an accumulation rate that is itself dependent on time. A memory representation and its physical basis are explained. The consequence is a theory that can be fit to observations successfully. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, a theory on the coalescence of signal receptor clusters in mast cells is developed in connection with experiments. The theory incorporates a feedback procedure and a time-dependent capture as part of a reaction-diffusion process. The study indicates characteristic features that need to be explained and shows why existing calculations in the literature are unsatisfactory. By considering dynamically evolving centers, the theory addresses the nature of coalescence, which continuously modifies the size of the cluster aggregate. The size of the signal receptor cluster aggregate is found to depend on time, and a comparison with experimental data reveals a sharp difference between theory and observations. The study introduces a time-dependent accumulation rate to address this discrepancy and explains its memory representation and physical basis. The resulting theory successfully fits the observations.