Liposomal muramyl tripeptide upregulates adhesion molecules on the surface of human monocytes.
We previously demonstrated that liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE), a biologic response modifier now undergoing phase III clinical trial in osteosarcoma, upregulated monocyte expression of several cytokines' mRNA and the subsequent production of these proteins. In the present work, we investigated whether L-MTP-PE upregulated adhesion molecules on the surface of normal human monocytes. Flow-cytometric analysis showed that several subunits of the integrins, including alpha L, alpha 5, and beta 1 subunits, and intercellular adhesion molecule-1 on the monocytes were upregulated following their stimulation with 2 micrograms/ml L-MTP-PE for 24 h. Anti-alpha L antibodies blocked monocyte-mediated tumor cell killing stimulated by L-MTP-PE. We conclude that L-MTP-PE also stimulates the increase of several molecules on the monocyte cell surface. These adhesion molecules may contribute to the increased activation of monocyte-mediated tumor cell killing seen following L-MTP-PE exposure.
Department of Cell Biology, University of Texas M.D. Anderson Cancer Center, Houston 77030, USA.
T
T
Asano
B W
BW
McIntyre
J L
JL
Bednarczyk
J N
JN
Wygant
E S
ES
Kleinerman
D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules / Q000097:blood*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004337:Drug Carriers; D005434:Flow Cytometry; D006801:Humans; D007155:Immunologic Factors / Q000494:pharmacology*; D016023:Integrins / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood; D008081:Liposomes; D016169:Lymphocyte Function-Associated Antigen-1 / Q000097:blood / Q000276:immunology; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects
D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; D004337:Drug Carriers; D007155:Immunologic Factors; D016023:Integrins; D008081:Liposomes; D016169:Lymphocyte Function-Associated Antigen-1; D010714:Phosphatidylethanolamines; D018799:Intercellular Adhesion Molecule-1; C037144:mifamurtide; D000119:Acetylmuramyl-Alanyl-Isoglutamine