Effects of liposome treatment and cytoskeleton-inhibiting drugs on the capping kinetics of rabbit T lymphocytes at various stages of differentiation.

The increased lipid fluidity of rabbit lymphocyte membranes resulting from treatment of the cells with soybean lecithin liposomes is shown to affect the capping kinetics of thymocytes, but not of peripheral T lymphocytes. Capping is induced by first treating the cells in the cold with a rat anti-rabbit T cell serum (ATS) followed by incubation at 37 degrees C with fluorescent (FITC) goat anti-rat serum. Untreated thymocytes belonging to subclasses with high proportions of mature cells are shown to cap slower than immature thymocytes. Interaction with soybean lecithin liposomes results in an enhancement of this capping kinetics, the strongest effect being observed in the case of the more mature thymocytes. This effect is not found with (mature) lymphocytes isolated from the mesenteric lymph nodes. The capping of these cells is strongly affected by cytoskeleton-inhibiting drugs, in contradiction to the capping of immature thymocytes. From these experiments we conclude that both the membrane fluidity and the action of the cytoskeleton are of importance in ATS capping of rabbit T lymphocytes dependent on the differentiation stage of the cells.