0000000000535254
AUTHOR
M. Letizia Vittorelli
Fisiopatologia. — Membrane vesicles, shed from in vitro cultured human breast carcinomas cells, inhibit lymphocytes proliferation.
Membrane vesicles are released by the cells of the two human breast carcinoma cell lines 8701-BC and MCF-7. Vesicles express on their surface HLA Class I molecules and tumor associated antigens and they appear to have a strong, dose dependent, inhibitory effect on thymidine incorporation by periferal lymphocytes. Inhibition is evident on both PhA stimulated or non stimulated lymphocytes. The inhibitory effect is visible after three days of culture. Vesicle addition does not cause cytotoxic effects since inhibited lymphocytes are still capable to exclude Trypan blue. No apoptoptic cells were observed.
Shed membrane vesicles and clustering of membrane-bound proteolytic enzymes
Publisher Summary Eukaryotic cells appear to release into the extracellular medium several populations of exovesicles, which are suggested to have different origins and functions and are identified by different names. This chapter deals with vesicles believed to originate from the cell membrane and named membrane vesicles. These are structures in which membrane-bound proteolytic enzymes are clustered and they play important roles in matrix remodeling. Relatively large membrane vesicles (diameters ranging from 100 nm to 1 μm) are shed from plasma membranes through unidentified budding mechanisms. These membrane structures are enriched in selected plasma-membrane components including integrin…
Membrane vesicles shed into the extracellular medium by human breast carcinoma cells carry tumor-associated surface antigens.
We have compared the pattern of surface antigen expression, as detected by monoclonal antibodies (mAbs), in plasma membranes vs shed membrane vesicles of two human breast carcinoma cell lines, MCF-7 and 8701-BC. Antigen expression was detected on cells by immunofluorescence (IF) analysis, whilst, due to their small dimensions, the same technique was not applicable to vesicles. For these structures dot-blot analysis and immunoelectron microscopy (IEM) were employed. When applicable, both cell membranes and membrane vesicles were immunoprecipitated and the precipitate (IP) was analyzed by SDS-PAGE. Cells of both lines expressed HLA class I antigens, epithelial cytokeratins, β1 integrins, CEA …