Redistribution of membrane proteins in isolated mouse intestinal epithelial cells.

Single mouse intestinal epithelial cells (IEC) may be isolated by the use of a combination of methods used for the isolation of IEC from other species. Isolated cells remain viable for several hours. The membrane integral enzymes alkaline phosphatase and leucine aminopeptidase of isolated IEC are localized to the brush borders of IEC in tissue and in most newly isolated IEC. With time, both enzymes are found distributed over the entire cell surface. Redistribution appears to occur by diffusion in the plane of the membrane. It is slowed, but not blocked, if cells are maintained at 0 degrees C instead of at 37 degrees C, and it is not blocked by fixation in 0.5-3% paraformaldehyde. Drugs that alter cell membrane potential or that affect cell levels of ATP enhance the rate of redistribution of the enzymes.

HUMORAL IMMUNOSTIMULATION

Interaction of microgram quantities of highly purified rabbit anti-TNP antibodies with TNP-substituted HeLa, HEp-2, and L cells caused an intense stimulation of radioactive nucleoside ([125I]UdR and [3H]TdR) uptake which was maximal 24–72 h after exposure of cells to antibody. The stimulation of nucleoside uptake and presumaly DNA synthesis was shown to be immuno logically mediated because unsubstituted cells were not stimulated by anti-TNP antibody, normal rabbit gamma globulin did not stimulate TNP-cells, and a hapten inhibitor, ϵ-DNP-lysine, prevented the stimulation of TNP-cells by anti-TNP antibody. These findings demonstrate that interaction of antibody with cell surface antigen can alter cell membrane transport, and possibly can enhance cell growth.