Inhibition of cell growth by macrophage membrane lipid molecule.
Macrophage hybridoma clone 5 suppressed B-cell proliferation induced by lipopolysaccharide (LPS). Since paraformaldehyde-fixed macrophages exerted the effect, macrophage-derived mediators were excluded from the inhibition. The inhibitory property of macrophages was present in the membrane fraction and was recovered in the organic phase after extraction using a chloroform/methanol/water system followed by hexane extraction. Therefore, the inhibitory activity found in macrophage clone 5 was concluded to arise from a lipid component. The inhibitory substance was further purified to a homogeneity by LH20 column fractionation using methanol/chloroform as the mobile phase. The purified lipid did not have any effect on the LPS-mediated induction of MHC class II molecules on the B-cell surface. Moreover, the inhibitory property was shown to affect growth of a wide variety of tumor cell lines of human origin. These results suggest that a lipid molecule found on the cell membrane of cloned macrophage hybridoma may participate in the regulation of cell growth through cell contact.
Uchida
T
T
Department of Safety Research on Biologics, National Institute of Health, Tokyo, Japan.
Naito
S
S
Mizuguchi
J
J
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D002450:Cell Communication; D002478:Cells, Cultured; D006131:Growth Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D008264:Macrophages / Q000502:physiology*; D008563:Membrane Lipids / Q000302:isolation & purification / Q000494:pharmacology*; D051379:Mice
D006131:Growth Inhibitors; D008070:Lipopolysaccharides; D008563:Membrane Lipids