Vesicle-vesicle adhesion by mobile lock-and-key molecules: Debye-Hückel theory and Monte Carlo simulation

Adhesion between cells is due to formation of weak, reversible chemical bonds between “lock” and “key” molecules imbedded in the cell surfaces. In this paper we present a theory for cell adhesion that extends the well-known Bell model of noninteracting adhesion molecules to include the cell-surface mediated elastic coupling between the molecules. We show that the statistical mechanics of this many-body problem can be mapped onto that of the two-dimensional Coulomb plasma with attractive forces. Using this mapping we find the following results: (i) the ideal-mixing state assumed by Bell and co-workers [Science 200, 618 (1978); Biophys. J. 45, 1051 (1984)] is unstable against migration of adhesion molecules to the rim of the adhesion disk in agreement with experimental observations and (ii) loss of adhesion is generally preceded by the collapse of the adhesion disk into a “stress-focused” state with enhanced adhesive strength.