Calcium-Dependent and-Independent Adhesion of Normal and Transformed BHK Cells

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Abstract
The adhesive properties of normal BHK cells and of their [polyoma virus] transformed derivatives (pyBHK) were studied by examining the aggregation kinetics after different treaments for cell dispersion. Cells dispersed with 0.005% trypsin with EDTA slowly aggregated only in medium with Ca2+. This aggregation was inhibited by cycloheximide. These cells acquired the ability to aggregate in medium without Ca2+ after preincubation in medium with Ca2+. Cells dispersed with lower trypsin concentrations (below 0.001%) with EDTA aggregated rapidly in the absence, and in the presence of divalent cations. Cells prepared by the above 2 methods did not require Ca2+ for the adhesion process per se (Ca2+-independent adhesion), but did require this cation for recovery of adhesiveness damaged by the earlier trypsin treatment. Cells dispersed with 0.005% trypsin solution containing Ca2+ aggregated rapidly in the medium with Ca2+, but did not aggregate in medium without Ca2+. The aggregation in Ca2+ was not inhibited by cycloheximide and required the continuous presence of Ca2+ in the assay medium. In this case, the mechanism must have required Ca2+ for adhesion per se (Ca2+-dependent adhesion). Both the Ca2+-independent and -dependent adhesion properties were found also in pyBHK cells, although the degree of Ca2+-dependent aggregation was less in pyBHK than BHK cells.