New theory and observations of cell adhesion

Over the years, attempts have been made to measure cell adhesion by several techniques, including, most recently, laser tweezers. Such tests have been used to interpret molecular theories of cell attachment and aggregation. However, the connection between adhering cells and molecular interactions is not fully understood. Here we define a new definition of cell adhesion which is exact and absolute at low cell concentrations. The idea is based on the statistical mechanics argument that particle bonding is directly related to the number of doublets existing in an ensemble. The theory is extended by computer modelling to high cell volume fractions. The benefit of this new theory is that it can be used in conjunction with cell counting machines, such as the Coulter counter, to obtain adhesion parameters directly, without applying any forces to the cells themselves. Experiments fitted the theory for human cells. The theory was also tested by using surface molecular treatments to alter the adhesive character of the cell suspension. Glutaraldehyde reduced adhesion, whereas dextran and fibronection increased adhesion of the red cells.