
the inhibition of cell aggregation by a pure
serum protein
the aggregation of embryonic chick and quail limb bud, heart and liver cells
in a shaker system has been investigated in order to elucidate the mechanism of
cell adhesion.
a new method of assessing aggregation is described and evaluated; this
method involved measurements of aggregation kinetics.  it was found that the
measured kinetics agree closely with flocculation kinetics, which provides a
direct quantitative measurement of adhesiveness in terms of the
probability of an adhesion forming on contact between two cells.
using this technique it was confirmed that aggregation is inhibited at
1-2 c. in the presence of serum but not in its absence.  the kinetics of
aggregation in the presence of serum at 37 c., the lack of inhibition of
aggregation at 1-2 c. by serum which has been 'conditioned' by the presence of
cells, and the similar lack of inhibitory power of serum which has been
pre-treated with antiserum antibodies, all suggest that serum contains a
factor which inhibits aggregation until destroyed by cellular metabolism.
