title: T cell activation via the disialoganglioside GD3: analysis of signal transduction.
abstract: The monoclonal antibody (mAb) R24 is a murine immunoglobulin G3 (IgG3) that reacts with the GD3 disialoganglioside present on melanoma cells as well as a subset of T cells. R24 mAb has induced antitumor responses both alone and in combination with interleukin-2 (IL-2) in clinical trials. We have reported T cell activation via GD3 as measured by the induction of tyrosine phosphorylation. In this study a more detailed analysis of signal transduction after ligation of GD3 was performed in an attempt to understand the mechanism of in vivo therapeutic benefits observed. Analysis of subsequent events indicated that GD3 engagement resulted in phospholipase C(gamma) phosphorylation and calcium flux. When ras-associated events were examined, GD3 signaling resulted in ras activation as determined by GDP/GTP conversion as well as dose-and time-dependent IP3 activation. In addition, the majority of the IP3 activation by GD3 was inhibited by herbimycin A pretreatment. Elucidation of the nature and potential role of this moiety in GD3 signal transduction should be useful. Collectively, these data suggest a novel mechanism of T cell activation via a single, non-protein, surface moiety. This novel form of T cell-mediated activation may permit the delivery and local activation of effector cells at the tumor resulting in site-specific activation of the immune system.
authors.affiliation: Laboratory of Experimental Immunology, National Cancer Institute, Frederick Cancer Research and Development Center, Frederick, Maryland, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Ortaldo
authors.forename: A T
authors.initials: AT
authors.lastname: Mason
authors.forename: D L
authors.initials: DL
authors.lastname: Longo
authors.forename: M
authors.initials: M
authors.lastname: Beckwith
authors.forename: S P
authors.initials: SP
authors.lastname: Creekmore
authors.forename: D W
authors.initials: DW
authors.lastname: McVicar
mesh_terms: D016227:Benzoquinones; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005732:Gangliosides / Q000502:physiology*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D047029:Lactams, Macrocyclic; D008213:Lymphocyte Activation; D010716:Phosphatidylinositols / Q000378:metabolism; D051966:Phospholipase C gamma; D010750:Phosphoproteins / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D011809:Quinones / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction; D019311:Staurosporine / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology*; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D016227:Benzoquinones; D004791:Enzyme Inhibitors; D005732:Gangliosides; D007527:Isoenzymes; D047029:Lactams, Macrocyclic; D010716:Phosphatidylinositols; D010750:Phosphoproteins; D011809:Quinones; D006153:Guanosine Diphosphate; D017828:Rifabutin; D019000:Phosphotyrosine; C026226:ganglioside, GD3; C020754:herbimycin; D006160:Guanosine Triphosphate; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D019311:Staurosporine; D002118:Calcium