London dispersion forces occur between all molecules. These very weak attractions occur because of the random motions of electrons on atoms within molecules. London dispersion forces are the only type of intermolecular attractions that exist in nonpolar molecules, such as O. London dispersion forces are due to the interaction between nonpolar electron cloud bonds, typically the C-C and C-H bonds in the hydrocarbon portions of polymer molecules.
The following figure shows that London dispersion forces are attractive forces between instantaneous dipoles.
In other words, Van der Waals forces play a major role in the stabilization of immune complexes. Similar attractive forces are also generated during the interaction of electron clouds of two non-polar atom groups. They are called London dispersion forces.