| Research Abstract |
A bacterial endotoxin lipopolysaccharide (LPS) is known to induce the expression of various cytokines via activation of host cells, including macrophages. To identify and characterize the novel molecules which play integral roles in the LPS-induced cell activation, we utilized antibodies against membrane proteins and isotopically labeled lipid A, and detected some candidates. We have previously shown that murine stroma-derived ST2 cells do not express CD14, and have approximately the same LPS responsiveness as macrophages. We here raised polyclonal antibodies against purified cell membrane from ST2 cells, as well as LPS binding protein partially purified from the ST2 cell membrane fraction by HPLC.Expression of particular proteins in the macrophage membrane was observed by concentration, separation and visualization of macrophage membrane proteins by immunoprecipitation and subsequent Western blot with antibodies raised against the membrane fraction. We also detected 57 kDa and 53kDa proteins as lipid A binding proteins by ligand blot, respectively with [^3H]-lipid A precursor (PE-406) and [^3H]-lipid A (PE-506).
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