Impact of cellular properties on red cell-red cell affinity in plasma-like suspensions.

The reversible aggregation of human red blood cells (RBC) by proteins or polymers continues to be of biological and biophysical interest, yet the mechanistic details governing this process are still being explored. In this report an approach is described to compute the interaction energy between RBC by considering cellular properties as well as polymer properties. Cell-cell affinities were calculated as functions of glycocalyx thickness and glycocalyx volume concentration as well as bulk polymer concentration. Our theoretical predictions show that cell-cell affinities do not monotonically increase with polymer size and concentration, but rather demonstrate an optimum dextran molecular mass and concentration which depends on cellular properties of RBC. These results show qualitative agreement with recent experimental observations. In conclusion, our model not only confirms the concept of a depletion mechanism for RBC aggregation but also provides new insights which should help understanding how cellular properties control in vivo RBC interactions.