MODEL FOR THE KINETICS OF HOMOTYPIC CELLULAR AGGREGATION UNDER STATICCONDITIONS

We present the formulation and testing of a mathematical model for the kinetics of homotypic cellular aggregation. The model considers cellu lar aggregation under no-flow conditions as a two-step process. Indivi dual cells and cell aggregates 1) move on the tissue culture surface a nd 2) collide with other cells (or aggregates). These collisions lead to the formation of intercellular bonds. The aggregation kinetics are described by a system of coupled, nonlinear ordinary differential equa tions, and the collision frequency kernel is derived by extending Smol uchowski's colloidal flocculation theory to cell migration and aggrega tion on a two-dimensional surface. Our results indicate that aggregati on rates strongly depend upon the motility of cells and cell aggregate s, the frequency of cell-cell collisions, and the strength of intercel lular bonds. Model predictions agree well with data from homotypic lym phocyte aggregation experiments using Jurkat cells activated by 33B6, an antibody to the beta(1) integrin. Since cell migration speeds and a ll the other model parameters can be independently measured, the aggre gation model provides a quantitative methodology by which we can accur ately evaluate the adhesivity and aggregation behavior of cells.