[Immunocytochemical analysis of the distribution and dynamics of lymphocyte antigens on freeze-fractured plasmatic membranes].

Label-fracture technique, which allows high resolution, coincident views of immunocytochemical markers on the cell surfaces and intramembrane particles (IMPs) over platinum/carbon replicas of the exoplasmic faces of the freeze-fractured plasma membranes, was used to analyze the surface distribution and dynamics of CD3, CD4, HLA class I and II lymphocyte surface antigens, all expressed on transmembrane proteins. In prefixed cells, the native distribution of the antigens was uniform over the cell surface. Coaggregation of IMPs induced by glycerol treatment at 37 degrees C before fixation revealed codistribution of the immunolabeling and the IMPs. Redistribution of the antigens, induced by treatment at 37 degrees C (for 20 min) with specific antibodies before fixation, resulted in capping of the immunolabeling in demarcated domains of the plasma membrane but failed to reveal correspondent domains of IMPs. This observation implies that migration of antigens into the patching/capping domains may be simultaneous with the exclusion of other membrane proteins from the same areas, as occurs during viral budding and receptor mediated endocytosis.