Surface coat of plasma membrane of L-1210 lymphoid leukemia cells. A cytochemical study.

In the plasma membrane surface coat of lymphatic cells L 1210 the negatively charged residues are distributed all over the membrane and are due mainly to neuraminic acid, as revealed by neuraminidase digestion followed by cationized ferretin (CF) binding. They bind eagerly to CF but not all of them bind ruthenium red (RR). In these cells RR seems to reveal rather hyaluronic acid residues, as suggested by hyaluronidase digestion. Basing on the known characteristics of CF one can calculate that neuraminic acid residues are grouped in assemblies including no more than 32 of them and spaced from 20 to 60 nm. The hyaluronic acid residues seem to be dispersed more irregularly. The membrane constituents bearing concanavalin A receptor are distributed in assemblies as well the distances between which may range up to 350 nm. After applying osmium-ferrocyanide and tannic acid reactions the surface coat appears as a continuous layer what indicates that the contrasted molecules are distributed at distances below the practically achieved resolving power of the microscope used.