Trypsin Effect on Intercellular Adhesion of Chick Embryo Fibroblasts

The paper shows that addition of trypsin (1—100 ug/ml) to a suspension of chick embryo fibroblasts dispersed from monolayer cultures at confluent state with EDTA gives rise to a pronounced cell aggregation. The aggregation begins just after the cells are brought in contact with trypsin and takes a few minutes. The trypsin-induced aggregation of chick embryo fibroblasts has two stages. At the first stage the amount of aggregated cells increases linearly with time and at the second stage, which occurs after about 10% of single cells have been aggregated, the rate of further aggregation increases sharply and nonlinearly. The total amount of the aggregated cells depends on the concentration of trypsin brought into the suspen­ sion and amounts to 40 to 80%. Data are presented, which support the suggestion that the second stage is induced by structural rearrangement of the plasma membranes, which involves cleavage of small but a critical number of peptide bonds on the cell surface.