Induction of macrophage-mediated tumor cytotoxicity by a hamster monoclonal antibody with specificity for lipopolysaccharide receptor.
Experiments have been carried out to assess the immunostimulatory activity of a hamster IgM mAb (mAb5D3) with specificity for an 80-kDa LPS-binding protein expressed on murine macrophages and monocytes. The addition of mAb5D3 to cultures of murine bone marrow-derived macrophages activated these cells to become tumoricidal for mastocytoma cells in vitro. The activity of mAb5D3 was enhanced in the presence of IFN-gamma. Neither mAb5D3 nor LPS were able to activate macrophages from the LPS-hyporesponsive C3H/HeJ mouse, although these cells responded normally to heat-killed Listeria monocytogenes. The results of several experiments establish that the observed LPS-like activity of mAb5D3 was not due to contaminating endotoxin: 1) the activity of mAb5D3 but not LPS was heat labile at 100 degrees C; 2) the activity of LPS but not mAb5D3, was inhibited by addition of polymyxin B; and 3) quantitative estimates of endotoxin contamination by Limulus amoebocyte lysate reactivity. These experiments thus demonstrate that mAb5D3 can serve as an agonist for LPS-dependent macrophage responses and, when considered with those of our companion paper showing specificity of mAb5D3 for the 80-kDa LPS-binding protein, provide strong support for the concept that the 80-kDa LPS-binding protein previously identified serves as a functional receptor for LPS on murine macrophages.
Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City 66103.
T Y
TY
Chen
S W
SW
Bright
J L
JL
Pace
S W
SW
Russell
D C
DC
Morrison
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D006224:Cricetinae; D003602:Cytotoxicity, Immunologic; D004306:Dose-Response Relationship, Immunologic; D006358:Hot Temperature; D007111:Immunity, Cellular; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides / Q000378:metabolism / Q000494:pharmacology*; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D009374:Neoplasms, Experimental / Q000276:immunology; D011112:Polymyxin B / Q000494:pharmacology; D011971:Receptors, Immunologic / Q000502:physiology*; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D011971:Receptors, Immunologic; D011112:Polymyxin B